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Definition of PTFE and Teflon Materials
1.PTFE (Polytetrafluoroethylene) also commonly known as Teflon Teflon.PTFE material has excellent dielectric properties (low dielectric constant and low dielectric loss), good chemical stability and thermal stability. Currently, it is suitable for the production of all high-frequency microwave single- and double-sided circuit boards,and PTFE multi-layer circuit boards will be developed later.
2.PTFE high-frequency circuit boards: There are pure PTFE high-frequency materials and PTFE high-frequency materials containing glass fibres.
3.Under cut drill: A kind of drill tip whose diameter below the neck is smaller than that above the neck, the contact area is relatively reduced during the drilling process,so that the quality of the hole wall can be very good. It is generally used for the drilling of special products such as lead-free, halogen-free,high Tg and PTFE.
4.Sodium naphthalene solution: a kind of chemical treatment of PTFE material hole slag solution,the effect is better,but the product is toxic, need to be strictly controlled.
5.PLSMA: Plasma treatment method, a kind of device that uses plasma to treat the slag in the hole of PTFE material,the price is more expensive and the copper immersion must be completed within 4 hours after the treatment.
PTFE PCB
PTFE material and Teflon material main operation method of each process.
1. Open the material to make FR-4 light board or phenolic board with double product feeding, which is used for drilling holes and moulding partition board.
2. If the PTFE sheet opened out by the opener has more burrs,use 2000# sandpaper to polish it and pay attention to the rubbing. In special cases, we need to use the gong plate method to open the material.
3. After washing the PTFE material and FR-4 board or phenolic board,put the PTFE material flatly in the middle of the board to bake the board, and put the board in the middle of the oven as much as possible when baking the board, at least 20cm away from the wall to ensure the effect of baking the board.
4. When drilling holes, first select UC drilling nozzles according to MI, and stack the plates in such a way that a base plate is put first, then a FR-4 light plate or phenolic plate, then a PTFE plate, then a FR-4 light plate or phenolic plate, and then an aluminium sheet.
5. Before copper sinking, prepare a plastic tray for GP-101 potion to open the tank, and put on a gas mask and rubber gloves and shoes. Put the plate into the tray and swing it evenly for about 10 minutes to ensure the reaction is complete.
6. Take out and rinse the plate with pure water for 5min, wash the plate twice with high pressure water without opening the grinding brush, pay attention to the warping of the plate and then normal through the plate grinding machine according to the normal parameters through the PTH, pay special attention to not need to go through the process of removing the slag because this kind of medicine has already played a role in removing the slag for the purpose of directly through the neutralisation and washing the whole hole after the micro-etching.
7. After the board electricity to confirm whether the board surface is rough, first with 2000 # sandpaper sanding, pay special attention to the control of sanding strength and the reverse side of the indentation.
8. PTFE material and Teflon material line can not open the grinding brush grinding board, only through the pre-chemical treatment, pay attention to the board surface cleanliness, the need to do the exposure before production scale, in order to save the parking time to choose a dry film to do the plate.
9. Pay attention to the control of burr when etching, the line width requirement is generally +/-20um, need to do the first board to confirm that there is no burr gap and the line width reaches the requirement before batch etching.
10. Solder resist before gold pretreatment not open grinding brush, before printing must be low-temperature baking board 75 ℃ * 15min, increase the bonding force of the ink and plate, ink plus open oil water 15-20ml/kg, after printing the green oil production board, need to be static for 60min and then pre-bake, before bursting the light must do bursting the light ruler.
11. After solder resist curing, must adopt segmented baking to do board, specific parameters see 5.3, for board thickness less than 0.8mm PTFE high-frequency boards and other high-frequency boards with high warpage requirements need to use laminar rack baking board.
12. Immersion gold can be pre-treatment, but not over grinding brush, if the surface oxidation is more serious can be over two times, the first plate of immersion gold to do the green oil tensile strength test, with 3M tape vertical 90 degrees does not appear to pull off the oil can be carried out in batch production.
13. Immersion tin plate ink is best to use solar ink, can be processed before the immersion gold without opening the grinding brush, do the first board to confirm that no oil and then do mass production.
14. When spraying tin, first bake the board at 150℃* for 30mins, and then spray tin immediately after pre-treatment. No oil will be removed from the layer before mass production.
15. When electro-golding, ensure that the vibration and mixing is normal, try to reduce the production of H2, reduce the production of pinholes, and must do the boards under the condition that all the concentration of the liquid is tested normally.
16. When OSP, make the first plate normally first, and then batch production after passing the test.
17. When forming, pay attention to the cleanliness of the table, the stacked plate is firstly put on a piece of FR-4 light plate or phenolic plate which has been used in drilling, and then put on the PTFE plate to be formed and then put on a piece of FR-4 light plate or phenolic plate which has been used in drilling. Input the gong belt to prepare the gong board.
18. Adopt the return method to reduce the burrs. Change the blade every 20feets. And the speed of gong should not be too fast, and vacuum once after each piece of gong. And we must do the first piece to make sure the size is qualified for mass production.
19. Be very careful when placing the boards because the PTFE material is soft and the holes are easy to deform, so it is not suitable to take the boards with great force so as not to break the positioning holes. Therefore, under special circumstances, the Causeway machine with automatic PIN removal can be used to ensure the precision on one hand and reduce the hole breakage on the other hand.
20. Bake the boards before testing to reduce the leakage rate of the boards.
21. Before shipment, the boards should be baked at 150℃*4h before shipment. Before baking, the surface of the platen should be cleaned up to ensure that it is clean before putting the boards into the oven for baking. If it is a gold plate, it should be baked with paper.
22. When packing, the FR-4 board or phenolic board of the same size as the board will be washed and cleaned, and then clamped on both sides of the board to make a partition for packing and shipping. If customers have special requirements, we will pack according to customers' requirements.
Note on PTFE and Teflon materials
1. The PTFE sheet itself is soft and easily deformed, and dents will appear when it is subjected to heavy pressure.Dents will occur when the sheets are placed together and debris is present. They need to be transported in plastic pallets throughout the production process.The boards should be cleaned.
2. When working with sodium naphthalene, be sure to observe the safety of toxic substances.You must wear rubber gloves,gas mask and rubber shoes. You must wear rubber gloves, gas mask and rubber shoes. Special attention should be paid to the fact that this solution is particularly sensitive to water and will react to make the solution ineffective,so it is necessary to control and isolate the water source during the production process. Add 100% of the original liquid.
3. Chemical micro-etching is used for the pre-treatment of this material in the production process.Physical grinding is not generally used for pre-treatment because the flexibility of the material is sensitive to grinding discs, so special control is required.
4. This PTFE high-frequency board is improved on the basis of impedance board, so impedance is the most basic requirement of high frequency, so impedance control is suitable for high-frequency board. So the impedance control is suitable for high-frequency boards, and some requirements are more strict than impedance boards.
5. During the production process,the printed circuit boards need to be placed flat to ensure that the warpage of the finished product is qualified.
6. Etching burrs and nicks must be controlled.Such defects in the finished product will appear as signal distortion and the performance will not meet the requirements. Therefore, HF board burrs should be controlled as a critical functional defect.
7. Care must be taken throughout the polishing process with fresh sandpaper. When sanding one side, attention must also be paid to the other side for indentation. The intensity needs to be controlled. Wash the polished board with water and stack it with white paper. 8.
8. During the whole process of picking up and putting down the boards, wear gloves, hold them flat and put them down flat.
9. The surface treatment cannot be done by grinding and brushing, you can switch off the grinding and brushing first, and then go through the immersion gold pre-treatment before doing the surface.
10. This PTFE Teflon material circuit board itself has poor resistance to acid and alkali. All processes must not be reworked without authorisation, not to mention patch lines.