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 [log in to unmask] cc 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 ******************************************* Shenzhen Kaifa Tech. Co., Ltd TEL:(86-755) 8303 2489 Ext: 33489 HP: 13480838497 E-MAIL:[log in to unmask] ******************************************* This message has been scanned. (210.245.235.14)