Affected by the Covid-19 in the past year, many companies have stopped work and production, the market growth of the electronics industry and the composite material industry has declined. However, the global market demand for FR4 epoxy insulating sheet and FR4 copper clad laminate has been increasing.

In the composite material industry, more and more companies are using FR4 epoxy insulation sheet to replace old materials. Among the copper clad laminates widely used in the electronics industry, the copper clad laminate of FR-4 material has always maintained its dominant position.

Excellent flame retardancy, insulation, and halogen-free environmental protection and safety in line with global certification. Under the sluggish global market, various factories are streamlining costs, but FR4 materials are at very good prices. These conditions have stimulated the market’s increasing demand for FR4 materials.

Here we share the two most common FR4 material process technologies based on our factory’s previous manufacturing experience.

FR-4 Resin System Process Technology

FR-4 copper clad laminate has been produced for many years, and the resin system is basically the same.

  • Preparation method

1. Dimethylformamide and ethylene glycol methyl ether are stirred and mixed to prepare a mixed solvent.

2. Add dicyandiamide and stir to dissolve.

3. Add epoxy resin and stir to mix.

4. Monomethylimidazole is pre-dissolved in an appropriate amount of dimethylformamide, and then added to the above materials, and continue to stir fully.

5. After being parked (curing) for 8 hours, take samples and test the relevant technical requirements.

  • Technical requirements for resin system

1. The solid content is 65%~70%.

2. Gel time (171°C) 200~250s.

The process technology of prepreg

  • Manufacturing process

After the glass fiber cloth is unrolled, which passes through the guide roller and enters the glue tank. After dipping, it passes through the squeezing roller to control the resin content, and then enters the oven. During the oven, the solvent and other volatiles are removed, and the resin is in a semi-cured state at the same time. 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.

  • Detection method

In order to ensure the quality, the resin content and other technical requirements must be tested regularly. The detection method is as follows:

1. At least 25mm from the edge of the prepreg, cut 3 samples according to the width direction to the left, middle and right. The size of the sample is 100mm×100mm, and the diagonal is parallel to the latitude and longitude.

2. Weigh the sample one by one (W1), accurate to 0.001g.

3. Put the sample in a muffle furnace of 524-593℃burn it for more than 15 minutes, or burn it until all the carbides are removed.

4. Move the sample to a desiccator and cool to room temperature.

5. Weigh the sample one by one (W2), accurate to 0.001g.

6. Calculation: Resin content=[(W1-W2)/W1]×100%

Cost-effective, environmentally friendly, and sustainable recycling, which must be the direction of future materials. The process of FR4 is also improving with market demand. As a factory specializing in the production and development of FR4 materials, we have been paying attention to the development of the industry, and our engineers actively participate in future material changes. Pls email [email protected] to get free FR4 sheet samples and learn more about the latest developments in FR4 materials.