Next thing we need to do is to solder the two layers together. Attach the lower layer to iPhone X specialized reballing mold.

Cover the lower layer with the matched reballing stencil.

Smear some low-temp Solder Paste on the stencil. Wipe off excess solder paste with the lint-free wipe. Once done, remove the matched reballing stencil carefully. Make sure solder paste has been applied evenly and perfectly.