2L FPC with 2 mil adhesiveless PI, ENIG(2u”) surface treatment

This design used 2 mil adhesiveless PI. Do you know the advantages of adhesiveless PI?

1. Thinner Thickness

As you know, the thickness of adhesive is around 12um, 15um, 20um, 25um, 50um. If you have strict requirement for the whole board thickness, it will be a good choice to use adhesiveless PI.

2. Better Bending

Adhesiveless substrate is thinner than adhesive substrate, so it’s bending is better.

3.  Heat resistance

Due to the adhesive have poor performance in heat resistance, so without the adhesive, the adhesiveless base material have better heat resistance.

Under the same temperature, such as 200℃，the tearing strength of adhesiveless PI change a little. But the tearing strength of adhesive PI material rapidly decrease.

4.  Dimensional stability

The dimension of adhesiveless board change very small when the temperature increase. Even under the temperature of 300℃, it’s dimensional changing rate is no more than 0.1%.

Good dimensional stability will be great help for fine wiring process.