(1) Manufacturing process After unwinding, the glass fiber cloth enters the glue tank through the guide roller. After dipping, it passes through the squeezing roller to control the resin content, and then enters the oven. During the oven, remove solvents and other volatiles, while keeping the resin in a semi-cured state. After leaving the oven, cut according to the size requirements, and neatly stack them on the storage rack. Adjust the gap of the squeezing roller to control the resin content. Adjust the temperature, air volume and speed of each temperature zone of the oven to control the gel time and volatile content.
(2) Testing method In order to ensure the quality of the adhesive sheet manufacturing process, various technical requirements must be tested regularly. The detection method is as follows:
1) Resin content: ① At least 25mm from the edge of the bonding sheet, cut 3 samples according to the width direction to the left, middle and right. The sample size is 100mm×100mm, and the diagonal is parallel to the warp and weft directions. ②Weigh one by one (W1), accurate to 0.001g. ③Place the sample in a muffle furnace of 524-593(, burn for more than 15 minutes, or burn until all carbides are removed. ④ Move the sample to a desiccator and cool to room temperature. ⑤Weigh each piece (W2), Accurate to 0.001g. ⑥Calculation: Resin content=[(W1-W2)/W1]×100%.
2) Gel time: ①Cut a sample of about 20cm×20cm from the center of the adhesive sheet, rub the sample to make the resin powder fall into the metal sieve, and then sift it onto a clean white paper. ②Take about 20mg of resin powder and place it in the center of the hot plate of the detector that has been heated up to 171 (±0.5°C) in advance. When the resin powder is melted, start the stopwatch and stir the resin with a wooden toothpick. ③ Stop the stopwatch when the resin thickens until the drawing is interrupted. The elapsed time is the gel time.
3) Resin fluidity: ① Cut 4 specimens at a distance not less than 5cm from the edge of the bonding sheet. The sample size is 100mm×100mm, and the diagonal is parallel to the warp and weft directions. ② Weigh (W1), accurate to 0.005 grams. ③The sample is aligned and laminated, and the release film is added, and then placed between the two stainless steel plates. ④ Put the steel plate and the sample in the press at 170℃±2.8℃, press once, the unit pressure is 1.4MPa±0.2MPa, and keep it for 10min. ⑤ Take out the sample and cool to room temperature. ⑥ Punch a φ80mm disc from the center of the sample. ⑦Weigh the weight of the disc (W2), accurate to 0.005g. ⑧Calculation: Fluidity=[(Wl-2W2)/W1]×100%.
4) Volatile content: ① At least 25mm away from the edge of the adhesive sheet, cut out 3 samples in the width direction to the left, middle and right. The sample size is 100mm×100mm, and the diagonal is parallel to the warp and weft directions. ② Make a small hole in one corner of each sample. ③ Put the sample in a desiccator for 1 hour. ④Weigh one by one (W1), accurate to 0.001g. ⑤Hang the sample in the oven and bake it at 163℃±2℃ for 15min. ⑥ Move the sample to a desiccator and cool for 10 minutes. ⑦Weigh one by one (W2), accurate to 0.001g. ⑧Calculation: Volatile content=[(W1一W2)/W1]×100%
(3) The storage of the adhesive sheet, after the appearance and various technical indicators are tested, the adhesive sheet should be stacked neatly, and the storage management shall be carried out as required. The epoxy resin in the bonding sheet is in a semi-cured state. During the storage process, the quality of the bonding sheet will change with the storage conditions and storage time. The changes in the moisture absorption rate of the adhesive sheet under various relative humidity conditions show that the moisture absorption rate of the adhesive sheet increases significantly when the relative humidity is high. The moisture absorption of the bonding sheet will seriously affect the quality of the product, especially the solder resistance will be significantly deteriorated.