Tuesday, May 25, 2010

Flex cable(FPC) Trace Pattern Layout Design Notices

Many FPCB designer are not familiar with the manufacturer and bring lot of quality issue after mass production. Here I summary some of the design notices for the flex cable (FPCB)  manufacturing  ability to prevent future quality fail.

1. Relationship between Through Hole, Land, Cover Film, and Cover Coat

Not Recommended

Recommended

flex_cable01 flex_cable02
flex_cable03 flex_cable04

The “Cover Film” must over to the soldering pad to prevent it from peeling off while soldering.

annular_ring1

2. Circuit Pattern Guidance

Not Recommended

Recommended

No sudden expansion or reduction in pattern width. No sharp angle. 避免在線路寬度突然變大或縮小,造成不應該的尖角出現。
 flex_cable05  flex_cable06

flex_cable07

 flex_cable08

3. Design at Folding Area

Not Recommended

Recommended

If the FPC need to be folded then the folding area shall be covered with cover film to prevent trace breaking. 如果軟板有彎折的需要時,建議Cover Film必須覆蓋過彎折處,以避免線路折斷。
  flex_cable09   flex_cable10
Avoid folding at below locations to eliminate the possible stress focus
a. The change of pattern width.
b. Folding parallel to the pattern.
避免以下的彎折及方法:
a.線路寬度改變的地方。
b.平行線路彎折。
flex_cable11 flex_cable12

4. Design at Folding Area

Not Recommended

Recommended

Plating leads and disconnection holes should be designed as illustrated in order to avoid short circuits. 相鄰線路應該盡可能用最大角度展開以避免短路。
flex_cable13       flex_cable14

5. Design at Folding Area

Not Recommended

Recommended

Avoid ending edge locate at same location for each layer.  
   flex_cable15    flex_cable16

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