Tinning Copper Pads On Ceramic Polycoated Substrates
Original Publication Date: 1982-Feb-01
Included in the Prior Art Database: 2005-Feb-08
A standard method of tinning the chip-attachment pads on a ceramic substrate is to submerge or dip a fluxed substrate into molten solder. Solder in contact with the flux wets the pads, and the process of soldering all pads is accomplished. The circuitry connecting these pads to pin locations must not be soldered; therefore, a chromium or a layer of organic film to act as a solder mask covers these regions. In those cases where an organic or poly coating is applied, the resultant design has small solder pads completely surrounded by a non-solderable surface and this surface, in most cases, extends above the plane of the solder surfaces. This condition creates a recessed window where the surface to be soldered is in a plane below the surface of the non-solderable coating.