Plywood with glass fiber on the surface of glass fiber board is made at high temperature and high pressure, and its outer surface has high quality moisture-proof performance. This plate is suitable for making containers. The dimensions provided are: the width of the plate can reach 3658 mm, the length of the plate can be any size, and the longest can reach 12 meter. The content of glass fiber is 25-40 wt%. Standard colors are gray and sub-white. Wood boards can be cleaned with steam.
The main technical features and applications of white FR4 optical board are: stable electrical insulation performance, good flatness, smooth surface, no pits, and excessive thickness tolerance. It is suitable for products with high-performance electronic insulation requirements, such as FPC reinforcement board, high-temperature board of tin-passing furnace, carbon diaphragm, precision planetary gear, PCB test bench, insulation partition board of electrical (electrical) equipment, insulation pad, transformer insulation, motor insulation, deflection coil terminal board, electronic switch, etc.
Among epoxy glass fiber boards, FR-4 glass fiber board has always maintained an absolute advantage and dominant position, occupying most of the middle and high-end markets. The main reason is that FR-4 is favored by the market because of its comprehensive industrial performance and high flame retardancy.
FR-4 resin adhesive
(1) resin adhesive formula In the epoxy glass fiber board industry, FR-4 glass fiber board has been produced for many years, and the resin adhesive formula is basically the same.
(2) Preparation method: 1) Mixing dimethylformamide and ethylene glycol methyl ether to prepare mixed solvent. 2) Add dicyandiamide and stir to dissolve. 3) Adding epoxy resin, stirring and mixing. 4) Dissolve 2- monomethyl imidazole in a proper amount of dimethylformamide in advance, then add it into the above substances, and continue to fully stir. 5) After standing (curing) for 8 hours, sample and test the relevant technical requirements.
(3) Technical requirements of resin adhesive: 1) Solid content is 65% ~ 70%. 2) The gel time (17 1℃) is 200 ~ 250 s. ..
bonding sheet
(1) Manufacturing technology After the glass fiber cloth is uncoiled, it passes through the guide roller and enters the glue tank. After dipping, the resin content is controlled by squeezing the rubber roller, and then it enters the oven. In the process of passing through the oven, volatile substances such as solvents are removed and the resin is in a semi-cured state. After leaving the oven, cut it according to the size requirements and stack it neatly on the storage rack. Adjust the gap of rubber roller to control the resin content. Adjust the temperature, air volume and vehicle speed of each temperature zone of the oven, and control the gel time and volatile content.
(2) Testing method In the manufacturing process of adhesive sheet, in order to ensure the quality, all technical requirements must be tested regularly. The detection method is as follows:
1) Resin content: ① Cut three samples from the left, middle and right along the width direction at least 25mm from the edge of the adhesive sheet. The sample size is 100mm× 100mm, and the diagonal is parallel to the warp and weft directions. (2) Weigh one by one (W 1), accurate to 0.001g.. (3) Put the sample in a muffle furnace of 524-593 (and burn it for more than 15 minutes, or burn it until all carbides are removed. (4) Move the sample to a dryer and cool it to room temperature. ⑤ Weigh (W2) one by one, accurate to 0.001g. ⑥ Calculation: Resin content = [(w1-w2)/w1] ×100%.
2) Gel time: ① Take a sample of about 20cm×20cm from the adhesive sheet, knead the sample to make the resin powder fall into a metal screen, and then screen it on clean white paper. ② Take about 20mg of resin powder and put it in the center of the detector hot plate which has been heated to 17 1 (0.5℃). After the resin powder melts, start the stopwatch and stir the resin with a wooden toothpick. ③ Stop the stopwatch when the resin thickens until the drawing is interrupted, and the elapsed time is gel time.
3) Resin fluidity: ① Cut 4 samples at a position not less than 5cm from the edge of the adhesive sheet. The sample size is 100mm× 100mm, and the diagonal is parallel to the warp and weft directions. ② Weigh (W 1), accurate to 0.005g. (3) Align and stack the samples, add the release film, and then place them between two stainless steel plates. (4) Put the steel plate and the sample into a press with the pressure of170℃ 2.8℃, and press once, with the unit pressure of1.4 MPa 0.2 MPa, and keep 10min. ⑤ Take out the sample and cool it to room temperature. ⑥ punch φ80mm wafer from the center of the sample. ⑦ Weigh the wafer (W2) to the nearest 0.005g and calculate: fluidity = [(WL-2W2)/w1] ×100%.
4) Volatile content: ① Cut three samples along the left, middle and right directions of the width at least 25mm away from the edge of the adhesive sheet. The sample size is 100mm× 100mm, and the diagonal is parallel to the warp and weft directions. ② Punch a small hole in one corner of each sample. ③ Put the sample into a dryer and treat it for 65438±0h hours. ④ Weigh one by one (W 1), with the accuracy of 0.001g.. ⑤ Hang the sample in an oven and bake it at 65438 063℃ 2℃ for 65438 05 minutes. ⑥ Move the sample to a dryer and cool it for 65438 00 minutes. ⑦ Weigh (W2) one by one, accurate to 0.001g. 8 Calculation: Volatile content = [(w1-w2)/w1] ×100%.
(3) The adhesive sheets shall be stored in neat piles as required after the appearance and various technical indicators have been tested. The epoxy resin in the adhesive sheet is in a semi-cured state, and the quality of the adhesive sheet will change with the change of storage conditions and storage time during storage. The change of moisture absorption rate of adhesive sheet under various relative humidity conditions shows that the moisture absorption rate of adhesive sheet increases obviously under high relative humidity conditions. After the adhesive sheet absorbs moisture, it will seriously affect the product quality, especially the immersion welding resistance will be obviously worse.
Therefore, in the storage process of adhesive sheets, moisture-proof problems must be given full attention! In order to ensure the product quality, it should be emphasized that the adhesive sheet should be stored at a temperature below 25℃ and a relative humidity below 50%.
restrain
The pressing process of epoxy resin copper clad laminate can be roughly divided into three stages: heating, heat preservation and cooling. The pressing process can be operated manually or controlled by computer. In the heating stage, heat is mainly transferred from the heating plate to the products in the interlayer, so that the resin melts and flows. At the same time, according to the melting and flow of the resin, pressurization is carried out. According to my years of work experience, this stage is the key to the suppression process. If the pressurization is not timely, it will cause "undervoltage" and appear defects such as "micro-bubbles" and "dried flowers". On the other hand, if the pressure is applied too early, it will lead to problems such as excessive glue flow or skateboarding.