Hello,
I could not find 1/8" PCB in my area (Toronto, Ontario, Canada) and wanted to glue two 1/2"x 2 1/2" x 1/16" thick PCB pieces with the 15 min. epoxy.
The PCB material is standard FR-4 glass-epoxy laminate, copper clad on one side only and I wanted to glue the other sides.
After roughing with #80 sandpaper and vacuuming, I degreased the surfaces with the mineral spirit and waited one hour for the spirit residue to evaporate.
Then, I glued the pieces and waited 24 hours.
Ten minutes ago I pulled the pieces apart very easily slightly bending the specimen. The epoxy was set but the in-plane shear strength and peeling strength of the connection was negligible.
Both previously glued surfaces have a thin layer of epoxy that sticks well to the base material.
Perhaps cleaning with the mineral spirit was a bad idea? Mineral spirit is used to clean epoxy and maybe its minute residue trapped in roughened surfaces affected the strength of the connection?
I know that many people use the 1/8" thick PCB material for the motor mounts glued to the fuselage sides using the epoxy resins so the strength of such connection was tested many times. There is not much bending, though, in such connection. It relies on the shear strength of epoxy between the PCB material and the fuselage front sides that are usually doublered with 1/64 or 1/32 plywood. The PCB mount is usually also framed on both sides by epoxied wooden pieces but some builders use only one side reinforcements with relatively small wood pieces.
Your comments and practical suggestions are appreciated,
Thank you,
M