Gold Fingers Polyimide(PI) Thickness Calculator

Usage

This tool calculates the thickness required of the PI stiffener from the desired connector thickness input by the user.

1. Available combinations of FPC, Copper, and Coverlay thickness:

The "FPC Thickness" in the table above includes the the thickness of coverlay and copper.

2. Calculation rules:

The thickness of the PI stiffener for gold fingers is not simply the connector thickness minus the FPC thickness; it needs to consider the impact of coverlay and copper thickness. The rules are as follows:

(1) If gold fingers have copper on the back: Subtract one layer of coverlay thickness (since gold fingers do not have cover film, this thickness needs to be subtracted).

(2) If gold fingers have no copper on the back: Subtract one layer of coverlay thickness and then subtract one layer of copper thickness (as gold fingers have no copper on the back, this additional copper layer needs to be subtracted).

For example:

if the total thickness in the gold finger area is 0.3 mm, the board thickness is 0.11 mm, and there is no copper on the back of the gold fingers, the theoretical thickness of the PI stiffener would be calculated as follows

PI Thickness = 0.3 - (0.11 - 0.0275 - 0.012) = 0.2295 mm. In this case, you should choose a PI thickness of 0.25 mm.

For more detailed Flexible PCB knowledge, please refer to JLCPCB Flex PCB Capabilities .