High frequency PCB fabrication

High frequency PCB needs special materials to realize the high frequency signal provided by this type of printed circuit board. Many PCB designers choose Rogers dielectric material because of its lower dielectric and signal loss, lower circuit manufacturing cost and more suitable for rapid turnover prototype application.

In addition to selecting the right PCB material and determining the correct Er value, the designer should also consider the conductor width and spacing, substrate constant and other parameters. The highest level of process control must be used to specify and implement these parameters precisely.

Rocket PCB is an experienced full-service PCB manufacturer, which can provide reliable and excellent high-frequency PCB fabrication services. Evaluate your requirements according to your design, rich variety of high frequency materials, mature high frequency PCB manufacturing experience.

What is high frequency PCB?

PCB high frequency board refers to the special circuit board with high electromagnetic frequency, which is used for high frequency (frequency greater than 300MHz or wavelength less than 1m).  Generally speaking, high frequency board can be defined as circuit board with frequency above 1GHz.  Substrate materials need to have excellent electrical properties and good chemical stability.  With the increase of power signal frequency, the loss requirement on the substrate is very small, so the importance of high-frequency material is highlighted.

High frequency PCB board with induction heating technology has been widely used in communication industry, network technology and high-speed information processing system, which meets the requirements of many high-precision parameter instruments. Reliable high frequency circuit board, in the actual production provides a great help.

What are the advantages of such a powerful high frequency pcb?

High efficiency

High frequency circuit board with small dielectric constant will also have small loss, and the advanced induction heating technology can meet the demand of target heating, and the efficiency is very high. Of course, while focusing on efficiency, it also has the characteristics of environmental protection, which is very suitable for the development direction of today's society.


The transmission speed is inversely proportional to the square root of the dielectric constant, which means that the smaller the dielectric constant, the faster the transmission speed. This is the advantage of high-frequency PCB, it uses special material, not only to ensure the characteristics of small dielectric constant, but also to maintain stable operation, which is very important for signal transmission.

Large degree of regulation

High frequency circuit boards, which are widely used in various industries for the heating treatment of precision metal materials, can not only realize the heating of components with different depths, but also focus on heating according to the local characteristics.  Whether the heating methods of surface or deep level, concentration or dispersion can be easily completed.

It is well tolerated

The dielectric constant and medium have certain requirements on the environment.  The use of circuit board will be seriously affected by humid weather. The high-frequency circuit board made of materials with low water absorption can challenge this environment.  At the same time, it has the advantages of resistance to chemical corrosion, moisture resistance, high temperature resistance and great peel strength, which makes the high-frequency circuit board play a strong performance

Processing characteristics of high frequency pcb

  • Impedance control requirements are relatively strict, relative to the line width control is very strict, the general tolerance of about 2%.

  • Due to the special material, so the adhesion of PTH copper is not high.  It is usually necessary to roughen the via hole and surface with the help of plasma treatment equipment to increase the adhesion of PTH hole copper and solder mask ink.

  • Do not grind the board  before soldermask, otherwise the adhesion will be very poor, only use micro etching solution to roughen.

  • Most of the materials are made of polytetrafluoroethylene, and there will be a lot of burr formed by ordinary milling cutter, so special milling cutter is needed.

  • Its physical properties, precision, technical parameters requirements are very high, commonly used in automotive anti-collision systems, satellite systems, radio systems and other fields.

Application field of high frequency PCB

  • Mobile communication products, intelligent lighting system

  • Power amplifier, low noise amplifier, etc

  • Power divider, coupler, duplexer, filter and other passive components

  • In the fields of automobile anti-collision system, satellite system and radio system, the high frequency of electronic equipment is the development trend.


Classification of high frequency PCB material

Powder ceramic filled thermosetting materials

A. Manufacturer:

Rogers 4350b / 4003c

Arlon 25N / 25FR

Taconic TLG series

B. Processing method:

The processing process is similar to that of epoxy resin / glass woven fabric (FR4), but the board is brittle and easy to break.  When drilling and punching, the service life of drill bit and Gong knife will be reduced by 20%.

PTFE material

A: Manufacturer

1.  Rogers Ro3000 series, RT series and TMM series

2.  Arlon AD / AR series, isoclad series and cuclad series

3.  Taconic RF series, TLX series and TLY series

4.   F4B, F4BM, F4BK, TP-2 of Taixing microwave

B: Processing method

1. Cutting: the protective film must be reserved to prevent scratch and indentation

2. Drilling:

  • Use a new drill bit (standard 130, presser foot pressure is 40psi

  • Aluminum sheet is the cover board, and then use 1 mm melamine backing board to tighten the PTFE board

  • After drilling, blow out the dust in the hole with an air gun

  • With the most stable drilling rig, the drilling parameters (basically, the smaller the hole, the faster the drilling speed; the smaller the chip load, the smaller the return speed)

3. Hole treatment

Plasma treatment or sodium activation treatment is beneficial to pore metallization

4.  PTH copper deposition

  • After micro etching (the micro erosion rate is controlled by 20 microinch), the board is fed from the oil cylinder after PTH pulling

  • If necessary, the second PTH will be passed, and the board can only be fed from the predicted cylinder

5. Soldermask

  • Pretreatment: acid washing, not mechanical grinding

  • After pretreatment, bake the board (90 ℃, 30min), brush green oil to solidify

  • Three stages of baking: 80 ℃, 100 ℃ and 150 ℃ for 30min respectively (if oil is found on the surface of the substrate, rework can be done: wash off the green oil and reactivate it)

6. Gong board

Lay the white paper on the surface of PTFE board line, and clamp it with FR-4 base board or phenolic base board with thickness of 1. 0 mm to remove copper:

The rough edge of the back board of the Gong board needs to be carefully scraped by hand to prevent damage to the base material and copper surface, and then separated with sulfur-free paper of a certain size, and visual inspection should be carried out to reduce the burr.  The key point is that the removal effect of the Gong board process should be good.


List of common high speed and high frequency PCB material parameters

List of common high speed and high frequency PCB material  parameters
supplierboardResin   typeMaterial   propertiesprice   indexapplication   area Evaluation   conclusion
DKDFTgTdZ-CTET288Water   absorption
SYSTS7439(EL230T)/3.80.0045200℃380℃/>60min0.08%/Network   equipment, measuring equipment
S7240/3.90.005200℃360℃2.00%>60min0.10%/Backplane,   server, router
ISOLAFR408FR4 +   hydrocarbons3.770.011180℃360℃3.50%200.15%//Board   thickness ≤ 2.0mm, pitch ≥ 0.8mm
FR408HR3.680.009200℃370℃2.80%300.06%3.2/Board   thickness ≤ 3.0mm, pitch ≥ 0.8mm
NECLON4103-13CE   (cyanate ester)3.70.009210℃365℃3.40%100.10%3.9Automotive,   aviation, defense, communications infrastructure, semiconductors, high speed   data
Mercurywave 9350/3.70.004200℃360℃2.50%40min0.15%/
PanasonicM4   (R5725)FR4+PPO3.80.005175℃362℃2.80%300.14%4
M6 (R5775K)PPO3.60.002185℃410℃/60min0.14%5.8
ROGERSRO4350BHydrocarbons   + ceramics3.480.0031280℃390℃0.63%60min0.06%8.3Satellite   TV LNB, microstrip line, power amplifier
RO3003PTFE   ceramics30.0013/500℃//<0.1%16.7Communication   satellite, backplane
RO4533PTFE   ceramics3.30.0025/500℃//<0.02%25Cellular   base station antenna
RO3730PTFE   ceramics30.0016/500℃//0.04%25Base   station antenna, satellite transmission antenna
ARLONTC350PTFE   ceramics3.50.002/567℃1.20%>60min0.05%6.5Power   amplifier, filter, connector
AD300CPTFE   ceramics2.970.002/555℃/>60min0.06%8.3Base   station antenna, power amplifier
CLTE-ATPTFE   ceramics30.0013/529℃/>60min0.03%16.5Car   radar, sensor
Multiclad/3.70.004205℃432℃1.20%>60min0.10%4Backplane,   power amplifier, receiver
TACONICRF35A2PTFE   + glass fiber3.50.0011/528℃2.65%/0.02%18Wireless   link, transmitter, power divider, combiner, filter, base station antenna
TLY-5PTFE   + glass fiber2.20.0009////<0.02%/
TSM-30PTFE   + glass fiber30.0015////0.03%36
TLX-8PTFE   + glass fiber2.450.0015////<0.02%/
RF35PTFE   + glass fiber3.50.0018////0.03%14
TLC-30PTFE   + glass fiber30.028////<0.02%/

High frequency PCB Process flow

1.  Npth PTFE board processing process

Cutting - Drilling - dry film - Inspection - etching – etching checking - soldermask- character - HASL- forming - testing - final inspection - Packaging - Shipping

2.  PTFE board processing flow of PTH

Cutting - Drilling - Plasma treatment or sodium naphthalene activation treatment-PTH- Plate plating - dry film-Inspection- pattern plating-etch-inspection-soldmask-silkscreen-HASL-profiling-test-FQC-packaging-shipping


Difficulties in high frequency board processing

1. Copper deposition: the hole wall is not easy to deposite copper

2. Control of line gap and sand hole in graph rotation, etching and line width

3. Green oil process: green oil adhesion, green oil foaming control

4. The scratch on the board surface is strictly controlled in each process


The advantage of Rogers PCB materials prototyping and costs

1. The commonly used high speed boards are as follows:

  • Rogers Rogers: ro4003, ro3003, ro4350, ro5880, etc.  

  • TUC:Tuc862, 872slk, 883, 933, etc. 

  • Panasonic: megtron4, megtron6, etc. ,

  • Isola: fr408hr, is620, is680,

  • Nelco: n4000-13, n4000-13epsi,

  • Dongguan Shengyi, Taizhou Wangling, Taixing microwave, etc

Rogers circuit board is very popular in the market.  Rogers brand materials are mostly used in the high frequency communication industry. 

2. Main substrate of Rogers circuit board

Rogers 4350b is one of the boards imported from Rogers, USA, which is mainly used in the production of high frequency circuit boards. In addition, there are also ro4350b, ro4003c, rt5880, ro3003 and ro3010. For detailed parameters, please refer to the materials data sheet on Rogers website.

Rogers high frequency board is usually mixed with special materials

Rogers and special materials, copper-based materials + Rogers become Rogers hybrid copper substrate PCB, and ceramic base + FR4 are Rogers communication hybrid base board, etc,

3. The cost of Rogers circuit board prototyping

Rogers high-frequency board prototyping costs, note that there are a few aspects of the composition,

  • Rogers base material model

  • The process requirement, the more complex the process, the more expensive the price

  • The number of layers, the higher the number of layers, the price will increase accordingly, and the difficulty of making boards will also increase

  • In addition, there are engineering costs.  If there is an urgent need, there are also urgent costs, etc

Rocket PCB is a professional high frequency PCB board manufacturer. Rogers high-frequency PCB prototyping is more done in the high-frequency board.  In addition, there are other high-frequency materials, such as tekonik high-frequency board, PTFE high-frequency board, Arlon, etc.

Rocket PCB has 10 years of PCB production experience, 300 skilled technical team, professional PCB and PCBA quality inspection team, to ensure product quality, delivery on time, high-frequency board as soon as 48 hours delivery, 24 hours uninterrupted quotation, timely solve customer problems. Please consult rocket PCB for more details.

Related reading

How to choose high speed and high frequency PCB material


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