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Terminology of printed circuit board-Part 1

Terminology of printed circuit board-Part 1

2020-05-20

Terminology  of printed circuit

In order to standardize and unify standards in PCB, so that countries and related industries can communicate with each other easily, a normative word is formed.

The following terms are commonly used. They are based on the national APCA standard and refer to the international standard IEC194 《printed circuit terms and definitions》, 1998 edition. They are

applicable to the fields of printed circuit substrate, printed circuit design and manufacturing, testing and PCB related fields. This paper only introduces the terminology of manufacturing, testing and

printed circuit.


1>IPC series standards

The abbreviation of IPC American electronic circuit interconnection and Packaging Association standard, which has been used for decades, is the parent standard of PCB quality standard because of its universal application. The series of standards added on this basis are also the application of PCB industry in the world.

IPC-A-600 "PCB acceptance conditions" is an indispensable reference standard for PCB specifications. IPC-A-600D was published in August 1989, IPC-A-600E was published in August 1995, and it was updated to version f in November 1999.This standard has not yet adopted a new numbering method, but IPC is currently considering whether to merge IPC-A-600 with the performance specification.

At the same time, in September 1991, IPC_D-275 "design standard for rigid printed boards and assemblies of rigid printed boards" replaced IPC-D-319 "design standard for rigid single and double sided printed boards" and IPC-D-949 "design standard for rigid multilayer printed boards". In April 1996, the first amendment of IPC-D-275 made a small amendment to IPC-D-275. In March 1998, the new PCB design standard IPC-2221 general standard for PCB design and IPC-2222 sub standard for rigid organic PCB design were published, replacing IPC-D-275. Recently, IPC-2221 issued the first amendment.

In addition, IPC has published many new standards and specifications, forming many standard series. The following is a list of two series

① Printed board design standard series

 IPC-2221  General standard for PCB design (replaces IPC-D-275)

IPC-2222  Rigid organic printed board design sub standard (replacing IPC-D-275)

IPC-2223  Flexible printed board design sub standard (instead of IPC-d-249)

IPC-2224  Pc card printed circuit board sub design sub standard

IPC-2225 Organic multi chip module (mcm-l) and its assembly design sub standard

 

② PCB performance specification series

IPC-6011 General Performance Specification for printed boards (replaces IPC-RB-276)

IPC-6012A Specification for the qualification and performance of rigid printed boards (in place of IPC-RB-276)

IPC-6013 Qualification and Performance Specification for flexible printed boards (instead of IPC-RF-245 and IPC-FC-250A)

IPC-6015 Identification and Performance Specification for installation and interconnection structure of MCM-L

IPC-6016 Specification for identification and performance of high density interconnect (HDI) layers or printed boards

Inspection and test of IPC-6018 microwave finished PCB (instead of IPC-HF-318A)

 

③ IPC General requirements

IPC-6011 General Performance specification for printed boards is a general performance specification for all kinds of printed boards, replacing the relevant parts of IPC-RB-276.

Grade of printed boards  IPC-RB-276 specifies three performance levels for printed boards:

1 Class - A general electronic products; civil consumer electronic products, including civil products, such as game board.

2 Class - The electronic products of special facilities require high performance and long life, and the performance is not very critical. Some defects are acceptable, including communication, computer and high frequency.

3 Class - High reliability electronic products, high reliability electronic products, which require continuous working and long standby time, are key to their performance requirements, including military, scientific research and industrial products.

IPC-6011 is also divided into these three levels, but the term "Military" increased by IPC-RB-276 is no longer mentioned. Now IEC62526:

The general specification for printed boards divides the functional level of printed boards into: A level of low environmental stress and low user expectation; B level of high environmental stress and high user expectation; C level is used to ensure continuous function, equipment or life support equipment that does not allow interruption. Japanese JIS PCB standard is divided into general function level, high function level and extra high function level. These are similar to the three performance levels of IPC PCB. The qualified products, first-class products and superior products in the quality grading standards of electronic products in China are classified from different perspectives.

 

④ Identification test and evaluation of printed boards

According to IPC-RB-276, qualification tests shall be carried out as required. IPC-RB-276 also specifies the sample making requirements and sample size test items for qualification test. It is limited to use IPC-a-100046 or IPC-a-100047 photographic plate to make samples.

IPC-6011 puts forward the requirement of "qualification assessment" with a broader meaning. Identification and evaluation is a method for users to select PCB suppliers. The appraisal and evaluation of IPC-6011 is first the self declaration of the supplier. According to IPC-MQP-1710 "OEM standard of PCB manufacturer appraisal program", the general situation of its field capability, processing and testing equipment, technical details, quality program, manufacturing history, company information and data verification sources are introduced comprehensively. Then the content of self declaration is verified, including the verification of quality profile and product characteristics. The data in the quality profile are verified by internal evaluation, statistical correlation of user evaluation and sample identification. IPC-6011 does not have a minimum requirement for qualification evaluation verification. It is up to the supplier and demander to consider the level of risk and cost to determine the level of verification applicable to their requirements.

The sample identification here is the identification test. IPC-6011 stipulates that this test can be carried out not only on a standard identification board in IPC-a-100047, but also on a test board simulating the production process, material and construction technology in the manufacturing of printed boards specified by the supplier, which shall be specified in the supplier's self declaration. The identification sample may be the actual finished printed board, the conformance attached test board specially designed for this purpose or other media used to establish the self declaration of the printed circuit board supplier. Specific identification test items shall be specified by relevant performance specifications of various printed circuit boards.


2> Definition of general terms


● Printed circuit

On the insulating substrate, the printed components or printed circuits formed according to the predetermined design and the conductive patterns combining the two

● Printed wiring 

A conductive pattern formed on an insulating substrate for connection between components, but excluding printed components

● Printed board

General term for printed circuit and printed circuit finished products. It includes rigid, flexible and rigid-flex single, double and multilayer printed boards

● Single-sided printed board

Printed boards with conductive graphics on one side only

● Double-sided printed board

Printed boards with conductive graphics on both sides

● Multilayer printed board

Printed boards with more than two layers of conductive graphics and insulating materials alternately bonded together, and conductive graphics interconnection between layers

● Rigid Printed Board

Printed boards made of rigid substrates

● Mother BoardA printed board that can be assembled with one or more printed board assemblies

● Component Side

One side with most meta-components installed. 

● Solder Side

The through hole is installed on the opposite side of the printed board and the component surface

● Conductor

A single conductive path in a conductive pattern

● Pattern

The configuration of conductive and non-conductive materials of printed boards also refers to the corresponding configuration on the relevant photographic negatives and drawings

● Character (Legend)

 Letters, numbers, symbols and figures used to identify the location and direction of components on printed boards

● Mark

A mark used to identify printed boards by product number, revision number, manufacturer, mark, etc

● Base Material

An insulating material on which a conductive pattern can be formed

● Inter Layer Connection

Electrical connection between conductive figures of different layers of multilayer printed boards

● Plated Through Hole

Hole wall plated with metal. Used for connection between inner or outer conductive patterns or between inner and outer conductive patterns

● Through Hole (Via)

A plated hole for electrical interconnection between wires in different layers of printed boards

● Blind Via

Vias extending only to one surface of the printed board

● Buried Via

Through holes that do not extend to the surface of the printed board

● Component Hole

Holes for fixing component terminals (including component leads and pins) to printed boards and making electrical connections

● Mounting Hole

Holes used to mechanically mount printed boards or alert fixing elements on printed boards

● Supported Hole

A hole whose inner surface is strengthened by plating or other means

● Unsupported Hole

Holes not reinforced with electroplated or other conductive materials

● Clearance Hole

On a conductive pattern of multilayer printed boards, a pattern coaxially with a plated hole but with a larger diameter

● Hole Location

Dimension position of hole center

● Hole Pattern

In printed boards, the arrangement of all holes relative to the reference point

● Connection Panel (Land)

The part of a conductive figure used for electrical connection, component fixation, or both

Annular Ring

The part of the conductive pattern that completely surrounds the hole

● Conductor Layer

All conductive patterns formed on either side of the substrate, including the ground plane and the power plane

● Internal Layer

A conductive pattern completely sandwiched in the middle of a multilayer printed board

● External Layer

Conductive patterns on the surface of multilayer printed boards

● Layer To Layer Spacing

Thickness of insulating material between adjacent conductor layers in Multilayer PCB

● Signal Plane

A layer of wire used to transmit a signal rather than to act as a ground or other constant voltage. Also called a signal surface.

● Ground Plane

A common reference or partial conductor layer used as a return, shield, or heat sink for a circuit

● Voltage Plane

 A layer of conductor or conductor that is not at low potential inside or outside the printed board


● Heat Sink Plane

 A thin metal layer in or on a printed circuit board, which makes the heat produced by the components easily dissipated

 ● Center To Center Spacing

The nominal distance between centers of adjacent wires, connecting plates, contacts, etc. on any layer of PCB

● Edge Spacing

The distance between the conductive figure or component body adjacent to the edge of the printed board and the edge of the printed board

● Cross Hatching

A large conductive area is segmented by using the blank figure in the conductive material

● Trim Line

A line that defines the boundary of a printed board

● Layer

In the computer aided design of PCB, it refers to component surface, welding surface, signal layer, grounding layer, power layer, solder mask layer, etc

● Multiple Printed Panel

A printed board in which one or more figures appear twice or more than twice as an independent work piece and are then separated

● Rework

The operation to make the unqualified products conform to the applicable drawing requirements or technical specifications by using the original process or the changed equivalent process

● Solder Resist

A general term for a heat-resistant insulating material used to protect the solderless area of printed boards

● Exposure

The process of exposing photoresists to ultraviolet light to produce polymerization or decomposition

● Undercut

Undercut or hollowing of wire edge caused by etching

● Conductor Width

 Usually the distance between the edges of the circuit

● Conductor Base Width

The width of the wire at the surface of the substrate

● Conductor Base Spacing

Wire spacing at substrate surface

● Desmear

The process of removing molten resin and cuttings from the hole wall

● Micro Etch

A process in which the surface of a metal is chemically slightly corroded, usually by coarsening

● Wetting Agent

An additive that reduces the surface tension of a liquid to make it easier to expand

● Process Conductor (Plating Bar)

Connect the temporary conductor of the plating part of the PCB

● Multilayer Layer Up

To prepare for lamination, the operation of aligning the layers of a laminate to overlap

● Black Oxidation

In order to improve the bonding force between copper surface and prepreg after lamination, the oxidation treatment process was adopted

● Punching

The operation of forcing the punch through the substrate into the die to remove part of the substrate

● Drilling

Use a high-speed rotary drill or laser to cut holes

● Foil Burr

Rough edge on the surface of foil after cutting, punching and drilling

● Deburr

The process of deburring by mechanical means (usually by rotating, abrasive nylon rollers)

● Production Board

Any printed board that conforms to the design drawings, relevant specifications and purchase requirements and is produced according to one

● Test Board

A printed board produced by the same process to determine the acceptability of a batch of printed boards. It can represent the quality of the batch of printed boards

● Test Coupon

A part of a graph of a quality conformance inspection circuit used for a specified acceptance inspection or a set of related tests

● Visual Examination

Examination of physical characteristics by the naked eye or by a specified magnification

● Blister

The phenomenon of local separation caused by local expansion between layers of base material or between base material and conductive foil or between base material and protective coating. It is a form of stratification

● Blow Hole

A cavity caused by exhaust, etc

● Bulge

The phenomenon that the surface of printed board or clad plate is raised due to internal delamination or separation of fiber and resin.

● Circumferential Separation

A crack or cavity in a coating around a plating hole, in a solder joint around a lead wire, in a solder joint around a blind rivet, or at the interface between a solder joint and a connecting plate

● Cracking

A breakage of a metal or nonmetal layer that may extend all the way to the bottom

● crack of foil

A break or break that partially or completely penetrates a metal foil

● Crack Of Plating

Partial or complete penetration of the metal coating including cracking or breakage of the outer layer

● Delamination

Interlayer of insulating base material, separation of insulating base material from any interlayer of conductive foil or multilayer board

 ● Dent

The surface of the conductive foil does not reduce the smooth depression of its thickness 

● Residual Copper

Unnecessary copper remained on the substrate after chemical treatment

 ● Fibre Exposure

The phenomenon that the reinforcing fiber is exposed on the base material due to machining or abrasion or chemical etching

● Weave Exposure

A condition on the surface of a substrate in which the fibers of unbroken woven glass cloth in the substrate are not completely covered with resin

● Weave Texture

A condition on the surface of a substrate in which the fibers of woven glass cloth in the substrate are unbroken and completely covered with resin, but the glass cloth has a marshalling pattern on the surface

● Wrinkle

Creases or wrinkles on the surface of the cladding

● Haloing

Breakage or delamination on or under the surface of substrate caused by machining

● Hole Breakout

The condition of a disc that does not completely surround the hole.

● Flare

In the process of punching, the tapered hole formed on the base material of the withdrawal surface of the punch

● Splay

Rotate the bit to produce eccentric, out of round or out of vertical holes

● Void

There is a lack of material in some areas

● Hole Void

A hole in a metal coating in which the substrate is exposed

● Inclusion

Foreign particles entrapped in base material, wire layer, coating, coating or solder joint

● Lifted Land

The phenomenon that the connecting disc is warped or separated from the base material, whether or not the resin is warped along with the connecting disc

● Nail Heading

The phenomenon that the copper foil on the inner conductor opens along the hole wall due to drilling in multilayer board

● Nick

A cut or notch in the edge of a wire

● Nodule

Irregular lumps or nodules protruding from the coating surface

● Pin Hole

A hole through which a layer of metal is completely penetrated

● pitting (PIT)

Holes that do not penetrate the foil completely

● Scratch

A fine line furrow made by a sharp object on the surface

● Bump

 Protrusions on the surface of conductive foil

 ● Conductor Thickness

Thickness of conductor including metallic coating but excluding non-conductive coating

● Minimum Annual Ring

 The narrowest metal width between the hole edge and the outer edge of the connecting plate. The inner layer of the multilayer board is measured from the borehole wall, and the outer layer and the double-sided board are measured from the edge of the plating layer of the plating hole

● Registration

The consistency of the position of the figure, hole or other feature on the printed board with the specified position

● Base Material Thickness

Thickness of insulating base material excluding surface metal foil

● Metal Clad Laminate Thickness

Including the thickness of the foil

● Surface Resistance

The quotient of the DC voltage between two electrodes on the same surface of the insulator divided by the steady surface current formed between the two electrodes

● Dielectric Constant

Values of current / electric field strength passing through the surface of insulating materials (fiberglass cloth). Dielectric constant values are generally required5.4MHZ.

● Surface Resistivity

The quotient of the DC electric field intensity on the insulator surface divided by the current density

● Bow

 A deformation of a laminate or printed board to a plane. It can be roughly expressed by the curvature of a cylindrical or spherical surface. If it is a rectangular board, its four corners are in the same plane when it is bent

● twist

A deformation of the plane of a rectangular plate. One of its angles is not in the plane containing the other three angles

● Dimensional Stability

Measurement of dimensional changes caused by temperature, humidity, chemical treatment, aging, or stress 

Solderability

The ability of a metal surface to be wetted by molten solder

● Solder Wetting

The molten solder is coated on the base metal to form a fairly uniform and smooth continuous solder film

● Ionic Contaminant

In the process of processing, the remaining polar compounds which can be dissolved in water are formed by free ions

● MICROSECTIONING

For the purpose of metallographic examination of materials, the method of preparing samples in advance is usually used to cut the section, and then fill with glue, grind, polish, etch, dye, etc

● Solder Float Test

Float the sample on the surface of the molten solder at the specified temperature for a specified period of time, and test the ability of the sample to withstand thermal shock and high temperature

● Machinability

The ability of a clad sheet to withstand machining such as drilling, sawing, punching, and shearing without cracking, crushing, or other damage

● Heat Resistance

The ability of a clad sample to withstand specified time and blister in an oven at a specified temperature

● Flexural Strength

The maximum stress that the material can bear when it reaches the specified deflection or when it breaks under bending load

● Tensile Strength

The maximum tensile stress at which a tensile load fracture is applied to a specimen under specified test conditions

● Flammability

Under the specified test conditions, the material has the capability of flame combustion

● Resin Content

Resin content of laminate or prepreg, expressed as the percentage of resin mass in the sample and original mass of the sample.


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