PCB Delamination, unfortunately is a fairly common problem for modern circuit boards, especially high-density, multi-layer boards or those composed of advanced materials such as PTFE (which is inherently difficult to bond to other layers). Boards are probably delaminating because, during processing, they are thermally and/or mechanically stressed beyond their limits of adhesion.

The risk of delamination increases with moisture absorption by PCBs. Delamination is generally a result of moisture content, PCB lamination control problems with Epoxy system and/or inherent stress that is evident in the PCB.

One way to reduce or eliminate this problem would be to increase the bonding strength between all the layers of the board, so that they don’t delaminate. This can be accomplished using a suitable plasma treatment on the layers of the board before they are bonded together. For example, increased adhesion (and decreased delamination) can be achieved by treating the individual layers of the board using an Argon-based plasma in a chamber in a low-vacuum environment, prior to the layers being bonded together to form the final board.

The plasma treatment can clean the layers and remove micro-contamination that interferes with bonding strength (this process is sometimes referred to as “plasma cleaning” the layers prior to bonding). The plasma treatment can also activate the surface of the layers before bonding together to make a finished board, so that each layer adheres more strongly to the other layers around it. Plasma treatments are particularly useful and effective when trying to bond advanced materials like PTFE or various flexible materials together such as polyimide, in order to prevent delamination and increase board quality.

It is also possible that the adhesive composition is non-uniform, which might allow delamination zones to occur. Also, surface contamination on the substrate will result in insufficient wetting between the adhesive and the surface, resulting in delamination. The smallest speck of dust can also cause a focal point for delamination to occur.

Additionally during the selection of PCB material, the moisture sensitivity properties shall be considered.