Epoxy Shrinkage Problem

[Mechineer]

I am using an epoxy to hold electrical contacts into an injection molded polyester block. Upon curing the shrinkage of the epoxy is significant enough the misalign the electrical contacts. I would like to know how to control the shrinkage without introducing new chemicals. For instance the epoxy already has %61 filler if I were to increase the filler this would decrease the shrink but the dielectric strength and mechanical strength would also decrease. Can the curing process have a significant affect on the shrinkage? Any info would be appreciated.

 

[rhodie]

When the solvent evaporates fully you lose 39% of your volume, if I am understanding your question correctly. The
cure time, however delayed by humidity or temperature, will always result in a 61% solid of the former volume.

My advice is to find a suitable epoxy with >61% filler, something that retains maybe 95% volume.

 

[rioindia]

Use 100% solids Epoxy system having low viscosity, which can be heavily filled. This will reduce shrinking problem. Shrinkage also depends on the type of curing agent used. R u using polyamide / polyamidoamine or polyamine system ? Have u incorporated any plasticizers ?

Regards Dielectric Strength..this can be significantly increased or decreased depending on the type of filler used.
If non-metallic fillers are used SiO2, Barytes, etc...the dielectric strength can be as high as 35-40 KV/mm.

Mechanical Strength can depends...Compression increases on increased loading ..however Shear strength and tensile & flexural strength reduces.