US 5,310,574 A · Method for surface mount solder joints

Abstract

A method and apparatus for the forming of a solder deposit on an SMD pad on a printed circuit or hybrid board. This formed solder deposit is in a defined three-dimensional well having the proper profile and a defined solder gap. The solder before forming can be solid solder or a solder paste. By the placement of a mesh on the surface of the circuit board with the solder in place on the pads, applying a slight positive pressure on a rigid or elastic surface on the other side of the mesh, and subjecting this system to a temperature just low enough to reflow the solder by means of a heat transfer fluid, then cooling the board to solidify the solder, a product results having the above properties. The duration of the application of heat and pressure is made so brief, that the laminate structure of the board and the coating thereon remain substantially unaffected. A circuit board with the solder so formed thereon.

Claims18

Dependent claims

A process for the forming of solder deposits on surface mount device pads comprising the steps of:

a) providing a printed circuit board having solder deposited on the pads;
b) covering said board with a mesh material;
c) placing said board with the mesh thereon between surfaces capable of uniform compression;
d) pressing together said surfaces;
e) placing said thus prepared circuit board at any orientation in a heat transfer fluid medium maintained at an elevated temperature whereby the solder melts;
f) removing said circuit board from the medium;
g) cooling said circuit board to ambient temperature while compressed;
and
h) removing said circuit board from between the compressive surfaces and the mesh.

6 more elements

Dependencies are inferred from the claim text.

Method for surface mount solder joints

Life of this patent

Method for surface mount solder joints

Life of this patent

Abstract

Claims18