High frequency circuit board production proofing

Definition of making high frequency circuit board High-frequency circuit board refers to a special circuit board with high electromagnetic frequency, which is used for PCB in high-frequency (frequency greater than 300MHZ or wavelength less than 1m) and microwave (frequency greater than 3GHZ or wavelength less than 0.1m) fields. It is a circuit board produced by using part of the manufacturing process of common rigid circuit board or special processing method on microwave base copper clad laminate. Generally speaking, high-frequency circuit boards can be defined as circuit boards with frequencies above 1GHz!
With the rapid development of science and technology, more and more equipment designs are applied in the microwave frequency band (> 1 GHz) or even in the millimeter wave field (30GHZ), which means that the frequency is getting higher and higher, and the requirements for the substrate of the circuit board are getting higher and higher. For example, pcb substrate materials need to have excellent electrical properties, good chemical stability, and with the increase of power signal frequency, the loss requirement on the substrate is very small, so the importance of high-frequency plates is highlighted. Second, mobile communication products in PCB high frequency board application field; Power amplifier, low noise amplifier, etc. Passive devices such as power divider, coupler, duplexer and filter; In the fields of automobile anti-collision system, satellite system, radio system, etc., the high frequency of electronic equipment is the development trend.
Mobile communication products in PCB application field; Power amplifier, low noise amplifier, etc. Passive devices such as power divider, coupler, duplexer and filter; In the fields of automobile anti-collision system, satellite system, radio system, etc., the high frequency of electronic equipment is the development trend.
Classification of high frequency boards Powder ceramic filled thermosetting materials
A, circuit board manufacturer:
Rogers company 4350B/4003C
25N/25FR from Arlon Company
Taconic company’s TLG series
B, circuit board processing method:
The processing flow is similar to that of epoxy resin/glass woven cloth (FR4), except that the board is brittle and easy to break, and the service life of drill and gong will be reduced by 20% when drilling and gong boards. PTFE (polytetrafluoroethylene) material
A. Manufacturer: RO3000 series, RT series and TMM series of Rogers Company.
Arlon’s AD/AR series, IsoClad series and CuClad series
Taconic’s RF series, TLX series and TLY series
F4B, F4BM, F4BK and TP-2 of Taixing Microwave
B. Processing method: 1. Cutting: the protective film must be kept for cutting to prevent scratches and indentations.
2. Drilling the circuit board
1. Use brand-new drill nozzles (standard 130), one by one is the best, and the presser foot pressure is 40psi.
2. The aluminum sheet is the cover plate, and then the PTFE sheet is tightened with a 1mm melamine pad.
3. Blow out the dust in the hole with an air gun after drilling.
4. Use the most stable drilling rig and drilling parameters (basically, the smaller the hole, the faster the drilling speed, the smaller the Chip load and the smaller the return speed)
3. Hole treatment of circuit board
Plasma treatment or sodium naphthalene activation treatment is beneficial to hole metallization.
4. PTH copper deposition of circuit board
1 After micro-etching (the micro-etching rate has been controlled by 20 micro-inches), the plate is fed from the oil cylinder in PTH.
2 If necessary, go through PTH for the second time, just from the expected? Cylinder start feeding plate
5. Soldering resistance of circuit board
1 Pre-treatment: Acid washing is adopted, and mechanical grinding is not allowed.
2. Pre-treat and bake the board (90℃, 30min), brush green oil for curing.
3 Bake the board in three sections: the first section is 80℃, 100℃ and 150℃, and the time is 30min each (if you find that oil is thrown on the substrate surface, you can rework it: wash off the green oil and reactivate it).
6. Circuit board gong board
Lay white paper on the circuit surface of PTFE board, and clamp the top and bottom with FR-4 substrate board or phenolic bottom board with a thickness of 1.0MM etched to remove copper, as shown in the figure: high frequency board gong board lamination method.
The burrs at the edge of the back of the gong board need to be carefully shaved by hand to prevent damage to the base material and copper surface, and then separated by sulfur-free paper of equivalent size, and visually inspected. To reduce burrs, the key point is that the effect of removing burrs during the gong board process should be good. Process NPTH PTFE plate processing process
Opening-drilling-dry film-inspection-etching-corrosion inspection-solder resist-character-tin spraying-forming-testing-final inspection-packaging-delivery.
Processing flow of PTFE plate for PTH
Material opening-drilling-hole treatment (plasma treatment or sodium naphthalene activation treatment)-copper deposition-plate electricity-dry film-inspection-drawing electricity-etching-corrosion inspection-solder resist-character-tin spraying-molding-testing-final inspection-packaging-shipment.
Summarize the difficulties in processing high-frequency circuit boards.
1. Copper deposition: the hole wall is not easily plated with copper.
2. Control of drawing, etching, line gap of line width and Chacon.
3. Green oil process: control of green oil adhesion and foaming.
4. In each process, strictly control the scratch of board surface, etc.