Microwave Tech - High frequency board process technology

High frequency board process technology

High frequency board process technology and quality control

1. Definition of high-frequency microwave printed board: High-frequency microwave printed board refers to the PCB used in the fields of high frequency (frequency greater than 300MHZ or wavelength less than 1 meter) and microwave (frequency greater than 3GHZ or wavelength less than 0.1 meter). The common rigid printed board manufacturing method is used on the microwave base copper clad laminate, and the printed board is produced by special processing in some processes.

2. Application of high frequency board:

1. Mobile communication products.

2. Power amplifier, low noise amplifier, etc.

3. GSM.CDMA.3G smart antenna.

4. Passive components such as combiners, power dividers, duplexers, filters, couplers, etc.

3. Classification of high-frequency boards:

1. Ceramic powder filled thermosetting material:

A. Manufacturer: Rogers’ 4003\4350 Arlon’s 25N\25FR Taconic’s TLG series

B. Processing method: It is the same as the ordinary FR4 processing process, but the sheet is relatively brittle and easy to break. The life of the drill tip and gong knife should be reduced by 20% when drilling and gongs.

2. PTFE material Rogers' R03000 series, RT series, TMM series, Arlon's AD/AR series, Diclad series, Cuclad series, Isoclad series, CLTE series Taconic's RF series, TLX series, TLY series, TLZ series, Neclo's N9000 series, Taixing Microwave's F4B, F4T, TP, TF and CTP series

Fourth, the main materials used for PTFE: Material composition: Polytetrafluoroethylene (English name: Teflon, referred to as "PTFE".

Material brand: A: Domestic material: F4B is a mixed material of PTFE and glass cloth Dielectric constant: 2.55, 2.65, 2.75, 2.85, 2.93, 3.0, 3.3, 3.5 Features: low loss, low cost, copper adhesion powerful

B: Imported materials: Taconic, Rogers, Getek, Nelcoc, Arlon

Process: NPTH's Teflon board production: cutting-drilling-dry film-inspection-etching corrosion inspection-forming-solder mask-characters-spray tin-testing (surface treatment)-forming-testing-final inspection-packaging-shipment The special features and quality control of FR4 products:

1. Cutting: The protective film must be kept to prevent scratches and creasing.

2. Drilling:

A. Adopt a new drill bit.

B. Laminated plate: 2 drilled plates are stacked below 1.6mm, and drilled plates are stacked with one meter above 1.6mm.

C. The imported material adopts phenolic board as the cover plate, and the domestic material adopts the aluminum sheet cover plate.

D. The drilling speed is 20% slower than FR4 board.

E. If there is still a sharp edge on the edge of the hole, use manual sanding with 2000# sandpaper. Do not allow mechanical sanding to cause expansion and extension to prevent sandpaper marks from scratching the copper surface.

3. Hole treatment:

A. High frequency pore refining agent.

B. Soak for half an hour.

4. Immersion copper:

A. First, confirm the wear mark of the plate before sinking copper: 8-12mm.

B. Since the sinking copper cannot be confirmed by the backlight, it is used on the lampstand to check the sinking copper effect with nine mirrors.

C. Rough surface and copper particles must be treated with 2000# sandpaper.

5. Picture transfer:

A. Confirm the wear scar before grinding the board: 8-12mm.

B. The line width and line gap are guaranteed to be within the compensation requirements of "MI", and the line width after development generally does not differ from the film line width by more than 0.01mm.

C. After developing, the blanks of the racks are not allowed to be filled with the racks to prevent scratches.

6. Picture and electricity:

A. The control clamp is broken, the board surface is rough, pinholes, fingerprints and other problems.

B. Hole copper thickness: minimum 18um, average 20um.

7. Etching:

A. Weaving is ±10%.

B. The etched board + allows bare hands to touch the substrate inside the board, which will pollute the surface of the substrate and affect the adhesion of the green oil.

8. Solder mask:

A. Pre-treatment••Using acid plate washing, not mechanical scrubbing.

B. Baking board after pretreatment: 85C.,30 minutes.

C. Use ink with good adhesion, such as: Sun: PSR-PSR-2000. Qing Zhengzhi: 30# Zhong-1 Xiaori Cun.

D. Check the green oil surface before alignment. Boards with poor appearance will be directly reprinted with green oil.

E. Green oil post-curing: All high-frequency boards must be baked in sections. Segment: 50C° for 1 hour.

The first second segment: 70C° for 1 hour. The third paragraph: 100C. 30 minutes. Fourth paragraph: 120C. 30 minutes. The fifth stage: 150C° for 1 hour.

9. Spray tin:

A. Baking board with solder mask before spraying tin: 140C° *60 minutes.

B. Baking board before spraying tin on board without solder mask: 110C°*60 minutes, 150C0*60 minutes.

C. Try to spray the tin while the board is hot to prevent the tin-sprayed board from peeling off.

10. Side of the gong:

A. Use special programs and special gongs and knives.

B. The speed of the gong must be 20% slower than that of FR-4.

C. The new gong knife is used, and the life span is 1 piece of 10 meters.

D. The burrs on the back of the gong must be carefully trimmed with a scalpel to prevent damage to the substrate and copper surface.

11. Packaging:

A. Because the board is soft and easily deformed, it is best to use waste cardboard to protect the empty packaging on both sides when shipping.

B. Immersion silver board must be separated from sulfur-free paper to prevent oxidation. Summary: Difficulties in making high-frequency boards.

A. Copper sinking: the hole wall is not easy to be coppered.

B. Control of line gaps and sand holes for image transfer, etching, line width.

C. Green oil process: Green oil adhesion and green oil foaming control.

D. Strictly control board surface scratches, pit marks and other defects in each process.

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