Adhesion problems

I get many questions sent in of which a fair proportion relate to problems of adhesion.  These can be largely divided into two problems. The immediate problem of lack of adhesion during metallization is one problem. The second problem is the delamination of the coating sometime after metallization.

It is always worth investigating the surface energy of the substrate with the intention of maximising the surface energy to improve the nucleation and adhesion.  Any surface treatment will clean the surface as well as increasing the surface energy.  This can also be part of the solution to the problem of post deposition delamination.

What helps in solving adhesion problems is collecting information. This should start with any information that arrives with the incoming material.  It should also include details of time, temperature and humidity.  It is surprising how many of the adhesion problems relate to climate changes.  If the substrate has been corona treated it is often set up in one season but then is used in all seasons. Changes in humidity will affect the corona treatment as the water vapour changes the plasma performance.  Also, after deposition, high moisture levels can end up with moisture appearing at interfaces where it can cause swelling and delamination.  This takes time and so may not appear as a problem until weeks after the metallization.

Thus my advice would always be to continuously record the temperature and humidity as well as film storage times so that any adhesion problems might be correlated against the atmospheric conditions.