PCB blister(delamination)

I am looking for a little enlightement with an issue that we have been seeing. We have printed curcuit board with multilayer and HAL finished. After reflow soldering, we have often "blister phenomenon". Our reflow profile is normal. Factory conditions is 23~28��/30~70%RH. We want to know the cause of the phenomenon. The sooner the better. Thanks for any insight. LG Information & Communication Ltd. Kumi, Korea email hjkim@lgic.co.kr

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| I am looking for a little enlightement with an issue that we have been seeing. We have printed curcuit board with multilayer and HAL finished. | After reflow soldering, we have often "blister phenomenon". | Our reflow profile is normal. Factory conditions is 23~28��/30~70%RH. | We want to know the cause of the phenomenon. The sooner the better. | Thanks for any insight. | LG Information & Communication Ltd. | Kumi, Korea | email hjkim@lgic.co.kr Hyeon-Jin, I believe you have improperly cured mask on your PWBs. Talk to your board vendor and tell him what you are seeing. Typically, blistering is caused when the board fabricators curing cycle is incorrect or out of control. The blisters result from moisture entrapped under the cured "skin" of the solder mask. Blisters are acceptable by IPC standards as long as there is no fluid entrapped or copper exposed. They are visually disturbing though and a point should be made to your vendor to ensure proper supply quality in the future. Regards, Justin Medernach

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