What is a PCB high-frequency board?

It refers to the special circuit board with high electromagnetIC frequency, which is used in the fields of high frequency (frequency greater than 300MHz or wavelength less than 1m) and microwave (frequency greater than 3GHz or wavelength less than 0.1m). It is a circuit board produced on the microwave substrate copper clad laminate by using part of the process of the common rigid circuit board manufacturing method or using special processing methods. Generally speaking, a high-frequency board can be defined as a circuit board with a frequency above 1GHz.

With the rapid development of PCB technology, more and more PCB devices are designed for applications in the microwave frequency band (>1GHZ) and even in the millimeter wave field (30GHZ). This also means that the frequency is getting higher and higher, and the requirements for the substrate of PCB are also getting higher and higher. For example, the substrate material needs to have excellent electrical properties and good chEMIcal stability. With the increase of power signal frequency, the loss on the substrate is required to be very SMAll, so the importance of high-frequency plates is highlighted.

Application field of high frequency plate

Mobile communication products;

Power amplifier, low noise amplifier, etc;

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

High frequency electronic equipment is the development trend in automotive anti-collision system, satellite system, radio system and other fields.

Classification of high-frequency boards

Powder ceramic filLED thermosetting materials

A. PCB manufacturer:

4350B/4003C of Rogers

Arlon's 25N/25FR

Taconic TLG Series

B. Processing method:

The processing process is SIMilar to that of epoxy resin/glass woven fabric (FR4), except that the plate is relatively brittle and easy to break. The life of the drill tip and the gong knife will be reduced by 20% when drilling holes and gongs.

PCB high-frequency board production

PTFE (polytetrafluoroethylene) material

A. Manufacturer:

Rogers' RO3000 series, RT series, TMM series

Arlon's AD/AR series, IsoClad series, CuClad series

Taconic's RF series, TLX series, TLY series

F4B, F4BM, F4BK, TP-2 of Taixing Microwave

B. PCB high-frequency board processing method:

1. Cutting: the protective film must be kept to prevent scratches and indentation

2. Drill holes 1. Use a new drill bit (standard 130), one by one is the best, the pressure of the presser foot is 40psi 2, the aluminum sheet is the cover plate, and then use 1mm melamine backing plate to tighten the PTFE plate

3. Blow out the dust in the hole with air gun after drilling

4. With the most stable drilling rig, drilling parameters (basically, the smaller the hole, the faster the drilling speed, the smaller the chip load, and the lower the return speed) 3. Plasma treatment or sodium naphthalene activation treatment of hole treatment is conducive to hole metallization 4. After PTH copper 1 micro etching (the micro etching rate is controlled by 20 microinches), when PTH is pulled from the oil cylinder to enter plate 2, if necessary, the second PTH should be passed, and only from the estimated? Cylinder starts to enter the plate

5. Soldering resistance: 1. Pretreatment: acid washing is used instead of mechanical grinding. 2. Pretreatment and baking (90 ℃, 30min). Brush green oil to cure the baking plate in three sections: one section at 80 ℃, 100 ℃, 150 ℃, 30min each (if the base material surface is found to shed oil, rework is allowed: wash off the green oil and reactivate it)

6. The gongs board shall lay white paper on the PTFE board line pavement, and the upper and lower parts shall be clamped with FR-4 base material plate or phenolic base plate with a thickness of 1.0MM, etched and copper removed,

Cladding method of high-frequency PCB gongs and boards The rough edges on the back edge of the gongs and boards need to be carefully scraped by hand to prevent damage to the base material and copper surface, separated by sulfur free paper of appropriate size, and visually inspected to reduce burrs, with the focus on good removal effect during the gongs and boards process.

high frequency board process flow

NPTH's PTFE plate processing flow

Process flow of PTFE plate of PTH

summary

Difficulties in high-frequency board processing

1. Copper sinking: the hole wall is not easy to be coated with copper

2. Control of line gap and sand hole of drawing, etching and line width

3. Green oil process: control of green oil adhesion and green oil foaming

4. Strictly control the scratch on the board surface in each process