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Delamination & Blistering IPC-A-600D
Although it may occasionally occur because of a severe process breakdown, delamination and blistering occurs as a result of an inherent weakness of the material. Either condition represents a breakdown in the cohesive strength of the composite laminate and the internal openings that develop can mechanically weaken in the final product and also provide undesirable conductive paths between circuit elements.
Delamination or blistering may occur in clad laminate materials either between plies of laminate, or between the laminate and the foil cladding. Any occurrence, either in the as-received condition or after routine thermal stress testing at receiving inspection is evidence of a major flaw, and the material should be rejected, since the defect will almost always propagate during the normal stresses of manufacturing.
Causes of Delamination "Quality Assessment Of Printed Circuit Boards"
The reason for delamination is epoxy starvation in the glass cloth layers or an incomplete curing of the base material. It has been reported that some manufacturers of laminates have reduced the lamination press cycle a little in order to increase production. In multilayer boards, visible delamination may be due to poor lamination of layers or insufficient bonding of prepregs to the inner layer copper circuits. Here, the PCB manufacturer is in a way also the "manufacturer" of the base material.
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