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Date: | Thu, 9 Aug 2007 08:50:58 +0800 |
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Sorry for my mistake on it,
For the cases, it totally depend on function of rework equipment.
2)生产线PCB板尺寸为190x155mm,厚度有1.04mm,有1BGA尺寸偏大 30x30mm(焊点
26x26),
在返修BGA台返修时,发现PCB板很容易变形,弓曲变形80%超过0.75%的标准(
IPC-A-610D 10.2.7)
不知有无好的工艺方法能避免PCB板变形?
comment Is it really 190x155mm of PCB size ? i really never see such big
pcb.
----- Forwarded by FP Deng/DG/Asia/Celestica on 2007-08-09 08:48 -----
FP Deng/DG/Asia/Celestica
2007-08-09 08:44
To
Asia Committe Task Group Forum <[log in to unmask]>, [log in to unmask]
cc
Subject
Re: [TGA] 请教PCB板变形&焊盘设计
Hi,
Here is comments in blue.
Liu Qixiong <[log in to unmask]>
Sent by: TGAsia <[log in to unmask]>
2007-08-09 08:22
Please respond to
Asia Committe Task Group Forum <[log in to unmask]>; Please respond to
[log in to unmask]
To
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Subject
[TGA] 请教PCB板变形&焊盘设计
Dear all,
早上好!
目前遇到2个问题,有些疑问,需要各位给出些建议:
1)我们遭遇到连锡,发现PCB板0805与0402焊盘间距离有0.22mm,分析为焊盘间最小
设计安全
距离为0.3mm,否则,会有焊点间会有牵引力,小元件就会被拉近大元件,形成偏
位或连锡。
从IPC标准上查,发现有光板导体间安全电气距离为0.13mm,(IPC-2221 表6-1)
,没有关
于焊盘设计的安全距离,不知有其他IPC标准规定?另牵引力的分析,是否有理论
依据?
象这种情况,如果PCB焊盘设计更改困难,有否其他工艺方法改善?
Comments.If it is hardly to modify related pcb design, stencil design
should be key solution, I think you should try to have more experiments to
optimize process parameter.such as stencil design, printing control,and
reflow profile as well.
2)生产线PCB板尺寸为190x155mm,厚度有1.04mm,有1BGA尺寸偏大 30x30mm(焊点
26x26),
在返修BGA台返修时,发现PCB板很容易变形,弓曲变形80%超过0.75%的标准(
IPC-A-610D 10.2.7)
不知有无好的工艺方法能避免PCB板变形?
comment Is it really 190x155mm of PCB size ? i really never see such big
pcb.
因刚加入这个组织,也许之前有讨论过,还请多多包涵。
以上,非常感谢。
Thanks and Best regards,
QiXiong Liu / 刘启雄
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