PCB glossary

A-stage

A-Stage refers to the woven glass fabric or cotton paper as the reinforcing material in the manufacturing process of the film, when the impregnation project is carried out through the glue tank, the glue (varnish) of the resin is still in the state of monomer and diluted by the solvent, which is called A-stage. On the contrary, when the glass fabric or cotton paper inhales glue and is dried by hot air and infrared, the resin molecular weight is increased to a complex or oligomer, which is then adhesive to the reinforced material to form film, at which point the resin state is called B-Stage. When it continues to be heated and softened and further polymerized into the final polymer resin, it is called C-stage.


ABS resin

It is a ternary mixed resin composed of Acrylonitrile-Butadiene-Styrene, in which the rubber part of butadiene can be corroded by chromic acid and become porous. It can be used as the landing point of chemical copper or chemical nickel, so it can continue electroplating. Many assembled parts on the circuit board are plated with ABS.


Base material

It refers to the resin and reinforcing material of the plate, which can be used as the carrier and insulating material for copper circuits and conductors.

 

C9omplsites, (CEM-1, CEM-3) composite material

It means that the substrate is composed of glass woven fabric, and the resin used is still epoxy resin. The outer layers of both sides of this plate are still pressed with copper foil with the impregnated film (prepreg) contained in the glass woven fabric, and the interior is a web (mesh) with resin-impregnated short woven mat. If the "mat" texture is still glass fiber, the plate is called CEM-3 (composite epoxy material). If the sheet material is paper fiber, it is called CEM-1. This is recorded in NEMA specification LI 1-1989.

 

Copper foil, copper sheet

The metal copper layer is pressed on the surface of the CCL copper foil substrate. The copper foil required by the PCB industry can be obtained by electroplating or rolled. The former can be used on general hard circuit boards, and the latter can be used on flexible boards.

 

Dry film

It is a dry photosensitive film resist used for image transfer of circuit board. There are two layers of PE and PET films to sandwich it for protection. During on-site construction, the isolation layer of PE can be torn off and the middle photosensitive resist film can be pressed on the copper surface of the board. After the negative film is photosensitive, the protective film of the pet can be torn off for washing and imaging to form a local resist for circuit graphics. Then etching can be performed(inner layer) or electron microscope (outer layer) process. Finally, after copper etching and film stripping, the board surface with a bare circuit is obtained.

 

Epoxy resin

It is a thermosetting polymer with a wide range of uses. It can generally be used for molding, packaging, coating, and adhesion. In the circuit board industry, it is the resin with the largest consumption for insulation and bonding. It can be combined with glass fiber cloth and white cowhide red to form plates and can accommodate various additives to achieve the purpose of flame retardancy and high function. It can be used as the base material of circuit plates at all levels.

 

Film negative

It refers to the film with existing line patterns, usually with a thickness of 7mil and 4mil. The photosensitive film includes black, white silver halide, and brown or other color azo compounds. This word is also called artwork.

 

Flame Resistant

Flammability refers to that in order to reach a certain flammability level in the resin of the insulating plate of the circuit board (divided into HB, VO, V1, and V2 in U.94), some chemicals must be deliberately added to the resin side, such as bromine, sand, alumina, etc. (for example, more than 20% bromine is added in FR-4), so that the performance of the plate can reach certain flammability. Generally, FR-4 with flame resistance is printed with a "green" watermark mark in the warp direction on the surface of the substrate (double-sided board).

 

Flammability Rate

Flammability rate refers to the degree of flammability or flame resistance of circuit board material. It refers to the specified grade that the plate can reach after the sample test is carried out according to the immediately determined test steps (as specified in 7.11 of ll-91 or lei-1988 of NEMA).

 

Flexible Printed Circuit

FPC board is a kind of special circuit board, which can change the shape in three dimensions during downstream assembly. Its base material is pullable polyimide (PI) or polyester (PE). Like the rigid board, this flex board can also make plated through holes or surface pads for through-hole insertion or surface bonding. The board surface can also be attached with a soft Coverlayer for protection and anti-welding Or printing soft anti-welding green paint.

 

Fluorocarbon Resin

Fluorocarbon resin is a series of organic fluorine-containing thermoplastic polymers, which can be used in the electronic industry. The main products include FEP (fluorinated ethylene propylene) and PTFE (polytetrafluoroethylene).

 

Flux

Flux is a kind of active chemical at high temperatures, which can remove the oxides or pollutants on the surface of the candle object so that the molten solder can be combined with the clean base metal to complete the welding.


Glass transition temperature

TG glass should be transformed into temperature. The polymer will change its physical properties due to the increase in temperature. When it is at room temperature, it is a crystalline amorphous brittle glassy material, and when it reaches a high temperature, it will change into a rubber-like elastomer, this narrow temperature ranges from "glass state" to "rubber state" is called "glass state transition temperature", which is abbreviated as TG, but it should be read as "Ts of G" to show that the transition temperature is not only at a certain temperature point.

 

Photographic film

Refers to the original carrier of green path pattern on circuit board, which is commonly known as "artwork". Commonly used are Mylar film and hard film of the glass plate. The film material of shading pattern includes black silver halide and brown azo compound (diazo)The former can almost block all kinds of light, while the latter can only block ultraviolet light below 550nm, while visible light with a wavelength above 550m will no longer have a photosensitive effect on the dry film. Therefore, the working area can be illuminated with yellow light, which is much more convenient than silver halide black-and-white negative can only work under dark red light.

 

Preg film, the Resin film

Glass fiber cloth or white kraft paper and other insulating carrier materials are immersed in liquid resin to make it fully absorbed, and then drag out and scrape away the excess content. After heated by hot air and infrared ray, the excess solvent is volatilized and partial polymerization is promoted to form a semi-national resin sheet of B-stage, which is convenient for the stacking and pressing of various substrates and multilayer plates. This prepreg is made by pre and pregnancy A new word.

 

Resin content

In the absolutely green base material of the board, except for the glass fiber or white kraft paper for reinforcement, the weight percentage of other resins is called resin content. For example, the U.S. military specification mil-p-139491 stipulates that the "resin content" of 7628 films must be between 35% and 50%.

 

Rigid-Flex Printed Board

A circuit board is composed of a rigid board and a flex board. The hard part can assemble parts, and the soft part can be folded and connected to reduce the trouble of joints and the volume of dense assembly and increase the reliability of interconnection. It is called rigid-flex in American terms, but it is called flex-rigid in Britain.

 

Solder mask (S / M) green paint

Solder mask is a common term, but solder resist is still a more formal term. The so-called anti-welding film refers to that some conductors on the surface of the circuit board that does not need to be welded are covered with a permanent resin film, which is called s / m. green paint can not only prevent welding but also protect the covered lines.

 

Teflon

It is a commercial plate of fluorocarbon resin of DuPont company, i.e. poly-tetra-fluoro-ethylene (PTFE). The dielectric constant of this resin is very low, only 2.2 at 1MHz. Even if it is combined with glass iron cloth with poor dielectric properties (such as R4737 of Panasonic Electric Co., Ltd., Japan), it can still be maintained at 2.67, which is still far lower than 4.5 of FR-4.

This kind of plate with very low dielectric constant, at an ultra-high frequency (3GHz ~ 30Ghz). In satellite microwave communication, the loss and noise caused by Mark transmission will be greatly reduced, which is a feature that cannot be replaced by other plates at present. However, the Teflon plate is very key selective, and its hole wall is very difficult to activate. Before PTH, a dangerous drug tetra etches containing metal sodium must be used to coarsen the hole wall of Teflon, so as to make the subsequent chemical copper layer have enough strength. And can continue the through-hole process.

Teflon plate still has other disadvantages, such as low Tg (19 ℃) and too large expansion coefficient (20pm / "C), so it is unable to make thin lines. Fortunately, the wiring density requirements of communication boards are far lower than those of ordinary personal computers, so they can be used at present.

 

Thin copper foil

Thin copper foil refers to the copper sheet pressed on the surface of copper foil substrate whose thickness is less than 0.7mi [0.002mm or 0.5oz].

 

Automatic optical inspection

It is optical equipment that uses ordinary light or laser light and computer programs to visually inspect the appearance of circuit board surface instead of manual visual inspection.

 

Backlight (buck lighting)

It is an enlarged visual inspection method to check whether the plated through-hole copper wall is intact. The basic method is to carefully grind the base material outside the whole wall from a certain direction to approach the hole wall, and then use the principle of resin translucency to shoot light from the thin base material behind. If the chemical copper hole wall is of good quality and there are no holes or pinholes, the copper layer must be lined and dark in the microscope. Once there are holes in the copper wall, a light spot must appear and be observed, which can be enlarged for photographic evidence. It is called the "backlight inspection method", also known as the through the light method, but only half of the hole wall can be seen.

 

Bond strength

It refers to the force (LB / in) applied per unit area in laminated plates when the adjacent layers are forced to be separated in a reverse way (not torn)²).

 

Cleanliness

It refers to the amount of the remaining parts of the completed board. Since the circuit board has gone through a variety of wet processes, once it is not cleaned enough to leave conductive ions, it will reduce the insulation impedance of the board, cause potential corrosion crisis of the board circuit, and even cause electron migration between conductors (including layers) under moisture and voltage Problem. Therefore, the board must be thoroughly cleaned and dried before being painted with green paint to achieve the best cleanliness. According to the requirements of MIL-P-55110D, the cleanliness of the board, expressed in terms of conductivity of its extraction solution (75% isopropanol and 25% pure water), must be lower than 2x10 "mho. If expressed in terms of resistance, it should be 2x10 6Ohm or above is considered as passing.

 

Hardness

Refers to the "resistance to penetration" of a substance against foreign invasion. For example, when a hard impactor is pressed on the metal surface with force, indentations of different sizes will appear due to different hardness and softness of the tested surface. Therefore, the depth or area of the indentation can determine the representative value of its hardness. Common hardness can be divided into "general hardness" and "general hardness" There are two kinds of "micro hardness". The former, such as high-strength steel, can be expressed by "RC-60" (i.e. 60 degrees of Rockwell "C" scale) on the surface after hard chromium plating and the hardness measured under the load of 150 kg of indenter.

The load is light during microhardness testing. For example, under the load of 25g, the microhardness measured by NUP Knoop indenter can be expressed as“KHN25150 "(i.e. carefully pressing a 25g loaded probe on the Jintu section under the microscope to obtain a number of 150 degrees based on the size of its long diamond) generally, the microhardness of the gold plating layer is often stressed for the sake of good wear resistanceKHN25 150-200 is appropriate. It is too hard and easy to wear. Generally, the microhardness of tempered pure gold will be reduced to about KHN25  80.

 

Penetrator

The indented tissue is presented by the two hardness meters.

 

Edge dip solderability test

It is a simple test method for the solderability of the circuit board (or other parts). After being stained with flux, the template of a specific circuit can be clamped with a tester or manual operation, vertically and slowly pressed into the molten tin pool, stayed for 1-2 seconds, and then slowly taken out. After cleaning, observe the tin adhesion of conductors or through holes on the board surface.

 

Impedance match

In an electronic circuit, if a signal is transmitted, it is hoped that it can be smoothly transmitted from the source of the power supply to the load under the condition of minimum energy loss, and it can be fully absorbed by the receiving end without any adverse reflection. In order to achieve such good transmission or transmission, the impedance (Z1) in the circuit must be consistent with the impedance (Z0) inside the "transmitting end". It is called "impedance matching".


Insulation resistance

It refers to the insulation of the plate between two conductors, expressed in volts.

"Between two conductors" here can be regarded as the conductor between two adjacent conductors on the board surface or between two adjacent layers of the multilayer board. The test method is to deliberately place the special fine comb circuit sample in the deteriorating environment of high temperature and humidity to test the insulation quality. The standard test method can be seen in the "moisture and insulation resistance" of IPC-TM650, 2.6.3D (Nov. 88) Test method. This hole becomes an approximate term, SIR.

 

Ion cleanliness 

The circuit board is completed through various wet processes, and the downstream assembly also needs to be treated with flux, so there are many ionic pollutants on the board surface, which must be cleaned to ensure no corrosion. However, the cleaning process requires isopropanol (75%) and pure water (25%). The resistance value or conductivity of the solution is measured after the mixed solution is washed, which is called ion cleanliness, and the plate surface pollution caused by ions is called "ion pollution".

 

MICRO SECTIONING

It is a technology for further understanding the plate level texture of the circuit board, the detail quality of the plate in each process station, and the assembly of parts. It is also a recognized quality inspection method. On the correctly polished and carefully micro-etched slice samples, under the magnification of 100 ~ 400 times, all kinds of details will be seen at a glance, and most of the root causes of the problems are also clear. However, the knowledge required for the correct interpretation of micro-slicing is far more than the technology of making it. It is almost an application of various theories and specifications such as materials, manufacturing process, and quality control. This micro-slicing method originates from the knowledge fields of metal materials and mining and metallurgy technology. MICROSECTIONING is a technology close to artistic creation, including the level of workmanship It takes up a huge proportion.

 

Omega meter ion pollution detector

How clean is the circuit board to be printed with green paint, or the assembly board to be assembled and cleaned? Are there still ion pollutants? It needs to be understood as a reference for the improvement of cleaning engineering. The actual practice is to immerse the board to be tested in isopropyl alcohol (accounting for 25%). In the mixed solution with pure water and make the solution flow so as to continuously wash the plate surface, dissolve any possible hidden ionic pollutants, and measure whether the conductivity of the test solution increases due to the continuous dissolution of pollutants with a conductivity meter, so as to judge the cleanliness of the plate. One of its commodities, the Onega meter is an instrument that continuously flows and continuously monitors the conductivity of the solution. That is, it is the best among them. Such products include omega500 of Kenco company, omega600 of alpha metal company, and monograph meter of DuPont.


Peel strength

In the circuit board industry, this term mostly refers to the adhesion strength of copper foil on the substrate. Its concept refers to tearing the 1-inch-wide copper foil on the substrate vertically from the plate surface to express the strength of the adhesion with the required force. Generally, the passing standard of 1oz copper foil is 81b / in. This term can also be used to express the adhesion of various electroplating layers. According to the Chinese national standard (CNS), The official translation of shall be "tear strength".

 

Porosity test

This is a test of the gold plating layer. The purpose of gold plating on the gold finger of the circuit board is to reduce the "contact resistance" and prevent oxidation and maintain its good contact performance. However, the coating is too thin to avoid pores. As a result, the nickel layer on the bottom plating has the opportunity to be close to air and water. Due to the noble chemical properties of gold itself, it is first selected as the cathode, forcing the nickel layer under it to play the role of the anode, resulting in accelerated corrosion of the bottom nickel. The corrosion products will adhere near the sparse holes, reducing the excellent contact properties of the gold plating layer. Therefore, in the quality specifications, the sickle gold layer is often required to pass through the porosity Test.

There are many methods for this test, one of which is to take a sheet stained with nickel reagent (dimethyl glyoxime) wet and press the test paper on the surface of the gold finger, and then take another stainless steel sheet as the cathode and press it on the test paper. Take the test paper as the electrolytic tank and the gold finger as the anode. After one minute of direct current, the bottom nickel layer with sparse holes in the gold layer will be forced to oxidize to produce nickel salt when it is mixed with "nickel reagent" When they meet, red spots will appear immediately. The sensitivity of this reagent to nickel concentration can reach 1.6 million parts. As long as there are pores in the gold layer, it can not escape the magic power of this test. However, it is difficult to formulate the "acceptance standard" of porosity quality.

 

Shear strength

In the circuit board industry, it refers to the object or part fixed and stuck by adhesive, which is pulled by reaction force along the direction of its connecting surface to cause slippage and separation. The maximum force of parallel pulling off along the surface is called shear strength. This term is also called lap strength or torsional strength.


Solderability

The solderability of metal bodies such as pins of various parts or circuit board pads is called solderability. Whether the circuit board or parts are solderable or not is the first problem to be faced in the assembly process. Poor solderability PCB and all other quality and characteristics will be put into the empty talk.

 

Solder spread test

A test of the effectiveness of the flux on the object to be welded. The method is to take a certain amount of solder, place it on the solderable metal plane treated with the flux, and then move it to the high-temperature heat source for fusion welding (usually flat in the tin pool). After cooling, observe the size of the molten tin dispersion area. The larger the area, the better the cleaning and oxide removal ability of the flux.

 

Spectrophotometry method

The metal salt solution will have the maximum absorbance at a certain wavelength. Based on this principle, the concentration of each metal solution can be monitored by using a specific photocell sensor. Before that, the standard measuring line must be made for the solution sample with a known concentration, and then the unknown solution concentration can be detected under the cooperation of this spectrometer and the measuring line. The instrument used for this quantitative analysis is called Spectro Photometer, whose detection rule is called spectrophotometry.


Tape test

Various coatings and organic coating layers on the circuit board can be pressed and attached to its surface with a small piece of transparent tape, and then pulled up instantly. The quality of the adhesion of these films can be measured. The commonly used transparent tapes are 3M's #600 and #691 products.


Tensile strength

It refers to an important mechanical property of metal materials. The layer to be tested can be made into a fixed "test weld" or "test piece" and installed on the tension machine for tension. The maximum tension before breaking is called "tensile strength".

 

Thermal cycle

After the circuit board or circuit board assembly is completed, in order to measure its reliability, it can be placed in the high and low-temperature loop return equipment to deliberately carry out severe thermal expansion and cold contraction to test the reliability of each conductor, part, and contact. It is an accelerated environmental test, also known as a thermal shock test or temperature loop withdrawal test. According to mil-p-55110, a complete cycle of thermal cycling test on the completed FR-4 circuit board shall be carried out in the following way: at room temperature, high temperature 125% within 15 minutes and 2 minutes, room temperature 15 minutes, low temperature - 65 ℃ within 2 minutes and 15 minutes, room temperature 5110d stipulates that FR-4 board must complete 100 cycles before its copper line conductor will deteriorate, from "resistance value"55110d stipulates that the resistance shall not exceed 10% of the original measured value, and there shall be no unacceptable defects after through-hole slicing.

 

Water Break

When the oil stain on the plate surface is cleaned and washed very clean, a uniform layer of water film will be formed on the surface after soaking in water, which can maintain good adhesion with the plate or copper surface (i.e. the contact angle is very small). Generally, when standing upright, the complete water film can be maintained for about 5 "10 seconds. When the water film is placed horizontally on the clean copper surface, it can be maintained for 10 ~ 30 seconds without breaking. As for the unclean plate surface, even if it is placed horizontally, it will soon appear" water breaking ", it presents a discontinuous "dewetting" phenomenon.

This is because the adhesion between the unclean surface and the water body is not enough to resist the cohesion of the water body itself. This simple way to check the cleanliness of the board surface is called the water break method.


Crack

In PCB, it often refers to copper foil or hole copper wrinkle layer plated with through holes. When tested by overheating stress, it often breaks locally or completely at all levels, which is called crack. Its detailed definition can be seen in Figure 7 of IPC-RB-276.


Crazing

It refers to the defect in the appearance of the substrate, which may be due to the split between the local glass fabric and the epoxy resin, or between the yarn bundles of the fabric itself. The white area visible from the appearance is called cracking. Those that are small and appear only on the weaving point are called "measuring". In addition, when the conformal coating is coated on the surface of the assembly board. The cracking is also called cracking. Generally, after the porcelain or ceramic tile for daily use is aged for a long time, there are irregular cracks on the surface due to the release of stress, also known as cracking.

 

Haloing

White edge refers to when the circuit substrate plate in drilling, slotting and other mechanical actions, once too strong, will cause the internal tree fat break or tiny meso-layer cracking phenomenon, known as Haloing, also some people use the word Pink Halo.

 

Hole breakout

It is called breakout for short. It means that part of the formed holes drilled wrongly have fallen outside the copper plate area or square copper pad area so that the hole wall can not be completely surrounded by the hole ring. That is, the hole ring has been broken and incomplete, which naturally greatly reduces the reliability of inter-layer interconnection. The responsibility for image transfer deflection is greater than the inaccuracy of drilling

 

Hole void

It means that on the through-hole wall of chemical copper and twice electroplated copper, if there is a hole on the hole wall with "see the substrate" due to negligence in the treatment process or poor bath liquid condition, it is called void. This hole wall hole has a bad impact on the quality of socket welding. It is often hidden in the hole due to the inhalation of water and oxygen, resulting in the ejection of oxygen from the broken place during high-temperature welding, The tin filled in the through-hole is blown into a hole before solidification, making this through-hole a blowhole. Therefore, it is known that a "broken hole" is actually the culprit of hole blowing.

 

Inclusion

In PCB, it refers to that foreign impurities may be mixed into the resin of insulating plate, such as coating or tin slag of metal conductor and various foreign matters of nonconductor, which are called inclusion. The foreign matters in this substrate may cause electric leakage or short circuit between board lines or layers, which is one of the items of quality inspection.

 

Mealing

According to the interpretation of IPC-T-50E, it means that the conformal coating coated on the board surface of the assembled circuit board floats point or sheet on the local board surface, or it may float locally from the parts, which is called bubble point or foaming.

 

Measuring white dots

According to the interpretation of IPC-T-50E, it refers to the local separation between the fiberglass cloth of the circuit board substrate and the resin at the warp and weft yarn weaving point. The reason may be that the plate is subjected to high temperature and stress pull. However, once the plate of FR-4 is exposed to free fluorine chemicals (such as gas deleted acid). When the glass is seriously attacked by infiltration, regular white spots will appear on each weaving, which is called measuring.


Misregistration

In the circuit board industry, misalignment refers to the alignment of some members (such as gold fingers or hole rings) on the front and back sides of the board, which should be aligned with each other. Once there is an offset, it is adjusted to "misalignment". Especially, the deflection between the hole rings of each layer sleeved outside each through-hole of the multilayer board is called "interlayer misalignment". In the micro slicing technology, it is easy to measure from its "misalignment" data.


Nick gap

The notch at the edge of the circuit board is called Nick. The other word notch is often used in machinery and is rarely seen on PCB. Dish down refers to the local subsidence of the circuit in terms of thickness.


Not wetting

When soldering with solder at high temperature, due to the uncleanness of the copper surface of the plate or the foot surface of the part to be soldered, or the presence of impurities such as oxides and sulfides, a necessary "interfacial alloy compound" (IMC, Cu6Sn5) is formed between the soldering method and the base metal copper. Such poor appearance cannot be "tin friendly". As a result, the cohesion of the molten tin itself is greater than the adhesion to the "surface to be welded", forming a situation that the molten tin is spherical and cannot diffuse. As for the overall appearance, it not only presents the situation of local aggregation and uneven but also exposes the bottom copper. This is more serious by "dewetting tin shrinkage", which is called "non-tin".

 

Oxidation

Theoretically, in a broad sense, any reaction that loses electrons can be called an "oxidation" reaction. Generally, in a narrow sense, oxidation refers to the reaction directly combined with oxidation. For example, all kinds of "rust" of various metals are oxidation reactions. Oxides refer to all kinds of oxides generated, and oxidizing agent refers to oxidants.

 

Pink Ring

At the interconnection between the hole ring on the inner layer plate of the multilayer board and the hole wall of the plated hole, the black oxide or brown oxide layer on the surface of the hole ring is eroded by liquid medicine and diffusely reduced to a bare copper surface of the ring primary color due to various processes of drilling and plating, which is called "PINK ring". It is a quality defect, and its cause is very complex.

 

Resin Recession

It refers to the resin in the B-stage film or thin base plate of the multi-layer plate (the former is the worst), which may not be completely hardened after pressing (i.e. the degree of polymerization is insufficient). After the through-hole is floating tin and filled with tin column, when slicing inspection is carried out, it is found that some resin with insufficient polymerization behind the copper hole wall will shrink from the copper wall and form a cavity, which is called "resin subsidence". this defect should be classified as the overall problem of the process or plate. To some extent, the process defect scratched by the plate surface is more serious, and the reason should be investigated carefully.

 

Scratch

All kinds of groove or V-groove scratches on the surface of an object.

 

Shadowing

This term is often used in the PCB industry in the process of infrared (IR) fusion welding and glue removal of plated through holes. The meaning of the two is completely different. The former refers to that there are many SMDS on the assembly board, which have been positioned with solder paste at the foot of their parts, and need to absorb the high heat of infrared for "fusion welding". In the process, some parts may block a ray to form a shadow and block the heat transfer, so that they cannot completely reach the required parts. This situation leads to insufficient maturity and incomplete fusion welding, which is called shading

The latter refers to the resin in the dead corners of the upper and lower sides of the inner copper ring during resin etch-back of some high-demand products before the PTH process. It is often difficult to be removed and form an oblique angle, also known as shading.

 

Skip Printing

In the process of board printing, missing printing is formed in some dead areas due to poor ink distribution, which is called skipping.

This phenomenon is most likely to occur in the conformal coating or green paint printing process. Because the corner on the back of the three-dimensional line is often not fully supplied with green paint due to uneven force or insufficient ink, it will form "missing printing".

As for the missing plating, it means that the plating may occur in the area with strong waste liquid disturbance or low current areas, such as the central part of the hole wall near the hole and the hole, or the poor distribution of the coating due to the obstruction of bubbles, which gradually makes it difficult to grow the coating. See also step plating.


Solder plug

It refers to the solder that flows into the plated through hole in wave soldering and remains in the hole after cooling to become a part of the conductor, which is called "Tin Plug". If there are plug-in parts in the hole, the tin plug also has the function of "welding point". At present, PTH, which is no longer used for plug-in but only for interconnection, has been changed into small holes with a diameter of less than 20mi1, which is called via hole. Both ends of these holes are covered with green paint to prevent the entry of flux and molten tin. Of course, there will be no Solder plugin this through-hole.

 

Solder Wicking

The wick effect of solder. Tin penetration refers to the penetration of some braided metal wires, or wires twisted into bundles, into the fine gap along the capillary tube when immersed in molten solder, which is called solder wicking.

 

Tombstone effect

There may be differences in solderability between the metalheads at both ends of small sheet-like surface-mounted parts and the welding pads on the plate surface. After infrared or hot air fusion welding, the floating phenomenon that one end is firmly welded and the other end is pulled up occasionally occurs, which is especially called tombstone effect or draw bridging effect, Manhattan effect, and other terms

 

Twist

Warping refers to the deformation and warping of the plate surface from the corners on both sides of the diagonal, which is called twist. There are many reasons. Most of the films with glass fabric are stacked in the wrong weft warp direction (the warp direction must be opposite to the warp direction, or the weft direction to the weft direction. The detection method of plate warping is to make three points in the four corners of the plate land on the platform, and then measure the height of the warping angle. Or use a ruler to span the diagonal, and then use a "hole gauge" to measure the floating distance between the ruler and the plate surface.

 

Warpage

Plate bending, a term used in the early PCB industry, refers to the problem of flatness of the circuit board, that is, the part where bending deformation occurs in the long direction of the board. The current term is called the bow.

 

Weave Exposure& Weave Texture

These two words are used in IPC-ΔSection 2.5 of 600 has a more correct description. The so-called "texture exposure" refers to that the resin layer on the surface of the plate has been damaged and lost, resulting in the exposure of the glass fiber cloth in the plate. The latter’s "texture looming" refers to that the resin on the plate surface is too thin and translucent so that the internal texture can be seen vaguely.

 

Wetting

When a clean solid surface is stained with water, it will spread evenly to all sides due to the large adhesion between them, which is called wetting. However, if the surface is not clean, the adhesion will become smaller and the affinity will be insufficient, which will make the cohesion of water greater than the adhesion, resulting in the accumulation of water. Any locally aggregated and discontinuous water droplets on the object surface are called "nonwetting". This expression of "wet" moisture, if extended to the solderability of circuit boards, becomes another meaning of "selling tin" and "poor tin" (or shrinking tin).

 

Air Knife

At the outlet of various process connection units, a knife-edge of high-temperature and high-pressure air is often installed to blow out the air knife, which can quickly blow the plate surface to facilitate access and reduce the opportunity of oxidation.


AQL

Acceptable quality level: select a small number of products for inspection in the quality inspection projects of a large number of products, and then determine the quality control technical balance of the whole batch trend.

Aspect ratio in the circuit board industry refers to the ratio of the length and diameter of the "through-hole", that is, the ratio of plate thickness to aperture.

 

Beveling

Refers to the contact front end of the golden finger. In order to facilitate access to the socket, the right angle edge lines on both sides of the right edge are specially cut off to form an oblique angle of 30 ~ 45 ℃, which is called "beveling".

 

Break-away panel

It refers to many circuit boards with a small area. For the convenience of plug-in, placement, welding, and other operations on the downstream assembly line, they are combined on a large board for various processing in the PCB manufacturing process. When the PCB is completed, the local routing is performed between the independent small boards in the way of tool jumping, but several tie bars or breakaway tabs with sufficient strength are retained IN addition, several small holes are drilled at the edge of the connecting piece and the board, or V-shaped notches are cut at the top and bottom to facilitate the breaking and separation of the boards after the assembly process. This joint assembly method of small boards will become more and more in the future, such as IC cards.

 

Chamfer

In the golden finger area of the board edge of the circuit board, in order to facilitate the insertion of its continuous contacts, not only the beveling work should be completed at the front edge of the board edge, but also the right angles of the board corner or slot opening should be removed, which is called "chamfer".


Clearance

The distance between the green paint printed on the outer board surface and each hole ring is also called clearance. However, due to the increasing line density of the current board surface, the original room for this green paint is almost empty.

 

Component Hole

It refers to the through-hole for the pin insertion of parts on the board. The average hole diameter of this pinhole is about 40mil. After the prevalence of SMT, the plug-ins with large hole diameters have been gradually reduced. Only a few gold pinholes of connectors still need to be inserted and welded, and most other SMD parts have been changed to surface bonding.

 

Component Side

In the early era when the circuit board was fully inserted through holes, the parts must be installed on the front of the board, so it is also called "a component surface"; the back of the board is also called the "soldering side" because it is only used for the tin wave of wave welding.

At present, both sides of SMT boards need to be bonded with parts, so there is no "component surface" or "solder surface", which can only be called the front or back. Usually, the manufacturer’s name of the electronic machine is printed on the front, while the UL symbol and production date of the circuit board manufacturer can be added to the back of the board.

 

Continuity Testing

It refers to the test on the energization of each line, that is, find two points at both ends of each line, make urgent contact with them with elastic probes (the whole board is implemented with needle bed), and then apply the specified voltage (usually twice the practical voltage) to carry out "connectivity test", which is commonly known as open/short testing

 

Desmearing

It refers to that when the temperature of the circuit board exceeds the Tg of the resin during the high friction heat of the drilling, the resin will soften or even form a fluid, and the hole wall will be coated with the rotation of the drill bit. After cooling, a fixed glue paste slag will be formed, resulting in a gap between the inner copper hole ring and the later copper hole wall. Therefore, at the beginning of PTH, the glue slag formed should be removed by various methods to achieve a good connection purpose.


Developing

It refers to the display of the next-generation photo or dry film pattern in the process of light-sensing image transfer. Since it is transferred from the "shadow" on the negative to the "image" on the board, it should be called "imaging".


Exposure

Using the energy of ultraviolet (UV) to make the photosensitive substances in the dry film or printing ink undergo photochemical reaction, so as to achieve the effect of selective local hardening and complete the purpose of image transfer, which is called exposure.

 

Fiducial Mark

In order to facilitate the downstream assembly on the board and the operation of its visual auxiliary system, large IC usually adds a triangular "reference mark" on the open space at each welded outer edge of the board assembly position to assist the placement machine in positioning. For example, PCB process often adds more than two reference marks to align the negative with the board in orientation.


Gerber File

It is a series of completed software files developed by the American Gerber company for circuit board surface circuit graphics and hole bits. The designer of the company buying the board can convert all graphic data of a material number into a Gerber file (the formal scientific name is "RS 274 format"), which is directly transmitted to the PCB manufacturer through a modem, then output from its own CAM, and cooperate with the laser plotter. Under the action of, specific operation data such as drilling, testing, circuit negative, green paint negative, and downstream assembly are obtained so that PCB manufacturers can immediately engage in proofing or production, and save more communication and waiting time. This kind of circuit board is "pre-manufacturing engineering". At present, the Gerber file is the standard operation of various data software in the global industry. In addition, another set of IPC-D-350d software has been developed, but it is still not widely used.

 

Ground plane (or Earth Plane)

The grounding layer is a kind of plate surface belonging to the inner layer of multi-layer plates. Usually, a circuit layer of multi-layer plates needs to be matched with a layer of large copper surface grounding layer to be used as the common return grounding of many parts, shielding, and heating.

 

Ground Plane Clearance

Whether the integrated circuit device is a traditional 1C or VLSI, its grounding pin or voltage pin is connected with the pinhole of its grounding layer (GND) or voltage layer (VCC), and then it is connected with a "one-way bridge" or "cross-bridge". Interconnect with the external large copper surface. For the through-hole passing through the layer, any bridge must be canceled to isolate it from the outside. In order to avoid deformation due to heat, an expansion layer must be reserved between the through-hole and the large copper surface to judge whether it is GND or VCC.

In general, if each station is mismanaged, a "PINK ring" will occur, but this pink ring should only appear in the annular ring within the clearance ring. The IPC American printed circuit board association was founded in 1957. In the beginning, it had only 6 members. It was a non-profit non-governmental academic community. It has become an international organization, and the total number of members of all groups in the industry has been close to 1500. Then in December 1977It was renamed "the Institute for interconnecting and packaging electronic circuits Association" June, but it is still abbreviated with IPC. However, its actual scope has been expanded from the early simple "circuit board manufacturing" to the current research on various engineering technologies and specifications such as plates, parts, and assembly. Its representative logo. After several changes, IPC is the most successful academic society in the circuit board industry in the world. It has led various professional research and formulated various important specifications, which are the archives of the upstream and downstream of the industry.


Just-In-Time (IT)

It is a production management technology. When the products to be manufactured or assembled on the production line, the production management unit will timely supply all the materials required. It even arranges the suppliers to send the raw materials or parts directly to the production line. This method can reduce the inventory pressure and the manpower and time of incoming inspection. It can also accelerate the logistics and speed up the delivery of products to catch up with the market Demand and grasp the best business opportunities.

 

Legend

It refers to the character element number or digital tag number printed on the surface of the finished circuit board, which is used to assemble or replace various parts, usually various parts (such as R of the resistor, C of the capacitor, U of th integrated circuit). The arrangement of is from the upper left corner of the front of the board, first to the right and then to the bottom, in order. The substitute words and numbers are given respectively according to the line of parts. This kind of text printing is mainly permanent white epoxy resin paint.

 

Lot Size

Batch refers to a group or a "batch" of products completed by a continuous process. Samples can be taken from them according to regulations, and inspected and tested according to specifications and acceptance criteria to determine the fate of the whole batch. The number of products in this "batch" is adjusted to "batch"

 

Major Defect

It refers to the defects found during the inspection. When they reach the "identification standard" with serious impact, they are formulated as serious defects. Those who fail to meet the identification are called "minor defects". Major originally means to express major or important ideas. For example, the main functions and main cadres are positive expressions. If they are used to describe negative "defects", they seem to be out of tune, so they are translated as "serious defects". It is appropriate. The above identification standards for the shortcomings of PCB have various situations. If there are express provisions, mil-p051 10d is the most authoritative.

 

Marking

That is, for words and symbols such as material number (P / N), revision letter, and manufacturer’s logo printed on the board surface with white epoxy resin paint, they can sometimes be used with legend, but they are different.

 

Microetching

It is a station in the circuit board manufacturing process. The purpose is to remove foreign pollutants on the copper surface. Generally, the copper layer below 100uinch should be stripped away, which is called "micro etching". The commonly used micro etching agents are "persulfate pin" (SPS) or dilute sulfuric acid plus hydrogen peroxide.

In addition, when performing a "microsection" microscope, in order to see the structure of each metal layer under high magnification, it is also necessary to micro etch the polished metal section to reveal the truth. This term is sometimes called soft etching or micro striping.

 

MotherBoard

Originally, it refers to the main board of a large computer, which can plug other assembly boards into this board as a circuit board for communication purposes. In order to withstand the plug-in and replacement of various assembly boards, its through-hole can not be welded. Therefore, the aperture tolerance of its through-hole is extremely strict, and other quality standards are also stricter than ordinary PCBs. This kind of board is also called "back panel"

However, since the rise of personal computers, the motherboard with CPU and various parts is also called motherboard

 

Mounting Hole

The mounting hole is an independent large hole without conductive function on the circuit board, which is used to lock the assembly board firmly on the body structure. This hole for mechanical purposes is called a "mounting hole". This word also refers to the mechanical hole used to lock the calibrated parts on the board with screws.

 

N. C. numerical control

It is the abbreviation of numerically controlled or numerical control. In the circuit board industry, it refers to the drilling machine, which accepts the command of the drilling paper tape in the programming machine, and controls the "numerical positioning" of the X and Y axes respectively during the synchronous movement of the countertop and drill shaft, so that drill tip can accurately stab at the predicted fixed point. This management method is called the "numerical control" method.


Panel Plating

After the through-hole (PTH) plating process is completed, the whole plate can be plated with copper for about 20 minutes, so that the copper wall of each hole can be thickened to 0.2 ~ 0.3mil, so as to ensure that the plate can safely pass through the subsequent "image transfer" process without errors. This kind of panel plating is commonly known as "primary copper" in the Taiwan industry, which is different from the "secondary copper" of the electroplating line after-image transfer". The practice of electroplating copper twice before and after such circuit boards can be regarded as the most stable and reliable mainstream in various processes. In the long run, it is still better than the" thick chemical copper "method.


Panel process full plate electroplating

In the orthodox reduction process of the circuit board, this is the method of obtaining the outer circuit by direct etching. The process is as follows:

PTH - plating thick copper on the whole board to the hole wall 1mil - positive dry film cover hole - etching - film removal - obtain the outer board of the bare copper circuit

The process of this positive film is very short. There is no need for secondary copper, tin plating, and tin-lead stripping. It is really much easier.

However, the thin line is not easy to do well, and its etching process is also difficult to control.


Punch

The plate to be processed is placed between the Yin and Yang molds, and then the forming of the "product individual" is completed by using the instantaneous impact cutting and sheer force of mechanical rotation, which is called punching. In general circuit board processing, the male mold is often punched towards the female mold to break the plate, while in general, the external shape of a single panel and various perforations can be constructed by punching.


Rinsing washing

In the wet washing process, in order to reduce the mutual interference of chemicals in each tank, the plates in various intermediate transition sections need to be thoroughly cleaned to ensure the quality of various treatments. The water washing method is called rinsing.

 

Silk Screen

Using polyester mesh cloth or stainless copper cloth as the carrier, the patterns of positive and negative pieces can be transferred to the mesh cloth of the mesh frame in the form of direct emulsion or indirect plate film to form a screen. As a printing tool for the surface of the flat plate, it is called the "screen printing" method. The mainland term is referred to as "silk screen printing".

 

Slot, slotting

It refers to the "slotting" at the edge of the PCB or somewhere in the PCB to meet the needs of assembly, which is called the notch. At the edge of the golden fingerboard, it is also called "polarizing slot or locating slot", which is deliberately biased to force the female connector of the golden finger not to be inserted reversely.

 

Solder Dam

It refers to the embankment formed by the thickness of green paint around the solder joint, which can prevent the short circuit caused by the flow of molten tin at high temperatures. Generally, the dry film anti-welding film is easy to form solder dam.

 

Solder Leveling

For the circuit board of bare copper circuit, each spot to be welded and hole wall are pre solderable in the way of solder coating. The method is to immerse the bare copperplate printed with green paint in the tin melting pool, make it covered with solder on the clean copper surface, and then blow away the excess tin in the hole and on the plate surface with high-temperature hot air, leaving only a thin layer of tin surface as the welding base. This process is called "tin spraying", and the term in the mainland industry is "hot air leveling".

 

Solders side

In the early stage of circuit board assembly, through-hole insertion was the mainstream. The front of the board (i.e. the component surface) was often used to insert parts, and its wiring was mostly arranged in the "board transverse" direction. The back of the board was used to cooperate with the tin wave of the pin passing through the wave welder, so it was called "welding surface", and its wiring was often arranged in the "board length" direction to comply with the flow of the tin wave. Other names of this word include secondary side, far side, etc.

 

Ultrasonic cleaning

The energy of ultrasonic oscillation is applied in some cleaning fluid to produce semi vacuum vesicles (Cavitation), and the friction force of the foam and the power of micro agitation is used to make the dead corners of the articles to be washed at the same time produce mechanical washout. This method is often used in cleaning the circuit board assembly board.

 

Ball Grid Array

It is a kind of pin packaging method for large components. Similar to the four pins of QFP, they are connected to the circuit board by SMT solder paste welding. The difference is that they are listed in the "one-degree space" around Single row pins, such as gullwing extension feet, flat extension feet, or J-shaped feet retracted from the abdominal bottom; change to a full array of local array at the abdominal bottom, and adopt the two-dimensional space area distribution of solder ball feet as the welding interconnection tool for the circuit board of the chip package.

BGA is a packaging method developed by Motorola in 1986. In the early stage, it was made of BT organic plate into the double-sided substrate to package IC instead of the lead frame of Fu Tong. The biggest advantage of BGA is the lead pitch. Compared with QFP, it is much looser. At present, the foot distance of many QFPS has been reduced to 12.5mil or even 9.8mil, which makes it very difficult to make PCB and downstream assembly. However, if the CPU with the same function is changed to BGA with full feet at the bottom of the abdomen, its foot distance can be relaxed to 50 or 60mil, which greatly alleviates the technical difficulties of upstream and downstream.

 

Organic Solderability Preservatives(0SP)

In order to save the solderable treatment layer of tin rolling and tin spraying, the early single panel was coated with an oily protective film on the surface to be welded of bare copper, called "pre flux", which is different from the flux pre flux used for downstream welding. Due to the adhesion of oily film and hindering electrical testing, this pre flux has never been used in the double-sided and multilayer board industry.

 

Pitch

It simply refers to the distance between the centers of two "units" on the board. The American formula in the PCB industry commonly uses mil-pitch, which refers to the span MI1 between the center lines of two welding pads. Pitch is different from spacing, which usually refers to the "isolation board surface" of two conductors, which is the area rather than the length.


Chat Online 编辑模式下无法使用
Chat Online inputting...
Thank you for your attention. Please kindly describe your question first, or please send your inquiry to our email sales@rocket-pcb.com, we will reply to you ASAP. Skype account: hans.hu@rocket-pcb.com welcome to consult!