Welded FPC Gold Finger Design Tips

Welded FPC Gold Finger Design Tips

Benefits of soldering FPC:

FPC soldering saves two board-to-board connectors or saves one Zif plug connector, saving 1-2 bucks. Therefore, on many low-end products, welded FPC is used. The disadvantage is that the welding area is larger than the connector, and the maintenance is more complicated.

Double-sided gold finger + tin hole

The gold finger corresponds to only one layer of pad, but the FPC’s gold finger can’t be just one layer. FPC is a non-metallic substrate with very slow heat transfer. If there is only one layer of gold fingers, the heat transfer of the soldering iron can not be soldered when soldering by hand. Similarly, the tin holes punched on the pads are also designed to transfer heat and allow the molten solder to flow between the upper and lower layers.

Double-sided routing + extra vias

Double-sided pads often cause PC disconnection during production, due to excessive stress on the FPC board. The reason for the damage: FPC can be bent, based on the overall stretch of the copper foil. After FPC welding, the welded surface cannot be stretched. Once pulled up, the force points are concentrated on the edge of the weld surface and the edges are pulled off. So you can improve it by designing “double-sided routing + extra vias”. The advantage of this “double-sided routing + extra vias” is that no matter how you fold, FPC will not be bad.

Grace Zheng

Email: sales06@andwinpcb.com

Skype: andwinpcb

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