第1个回答 2013-03-25
Cause:
The pictures shown in the report returned by the clients indicate that SN4 and SN5 were mainly caused by jointing abnormity.In picture SN4, there were many scaling powder around U1, it's an obvious sign of duplicating work.
The container U1 is sticked up by machine and there hasn't any abnormal problems about the opennings of the steel mesh mat, there are few via holes in the corresponding bonding pad of PCB and they were linked to the ground hole in the middle.We assumed that it may be the lossing of tin in the process of fluid welding that caused rosin joint.
lossing reason:
The rosin joint problem is now mainly checked by manpower,so the negligence of human may cause the defective products out.
No stock products and online products
1.remove the via hole in the correspond bonding pad of PCB,prvent the tin from lossing, at the same time, add some mark points to make sure that the stick can be done correctly
2.optimize the opennings in the steel mesh mat(By increse the length of the bonding pads that have via holes correspond with the opennings of the steel mesh mat, to get the effect of making up for tin)
3.train the emploees on checking rosin joint and unsysmetic on and around U1, and add this to the rule of checking
4.Test as the way that is provided by the client before shipment
stategy valid
第2个回答 2013-03-25
如下,不过以我这么多年的QM经验,这种分析我并没有看到确实有效的分析方法和根本原因验证.要是我是客户或者你们的品质经理的话,这个报告我是不会接受的.呵呵~~
Root cause:
The root cause of the customer complaint has identified as improper manual soldering, as a high amount of solder flux is observed around the U1 of picture SN4, there is significant trace of touching up manually.
The U1 was auto mounted in production, the stencil aperture is also found no issue. however, few of the via hole was found connected to the grounding hole at the central of PCB, this could result insufficient during reflwo.
Occurrence:
We are currently performing visual inspection for nonwetting issue, operation error caused escape.
Containment:
No Finished goods or WIP on hand
Action:
1. Remove the via hole to avoid solder paste flow away, relay the reference point (参考点有不同叫法)
2. Optimize the stencil by larger the aperture
3. Enhance operator ability to capture the nonwetting or misalignment, especially components around U1. update work instruction accordingly
4. Perform testing by follow customer requirement.本回答被提问者采纳
第3个回答 2013-03-25
Cause of fault :
According to photos SN4 & SN5 included in the client's analysis feedback report , it is apparent that the fault lies in the soldering process. In photo SN4, it shows excessive soldering flux around U1 as it had been re-processed﹒
U1 is surface mounted on to the pcb and there is no apparent defect in the SM stencil . Therefore , the above mentioned fault could be caused by the short-circuited soldering between the plate through holes and the ground hole around U1 during reflow process ，in which considerable amount of solder being lost thus non-wetting was caused .