Lead frame preparation for solder dipping
AssigneeNational Semiconductor Corporation
InventorFrancis W. Layher
Life of this patent
Estimating the term…
Abstract
Metal leads are prepared for solder dipping by first exposing the leads to a fifty percent solution of sulfuric acid. The leads are then rinsed using city water and exposed to solution consisting of fifty percent sulfuric acid, twenty-five percent nitric acid and twenty-five percent deionized water. The leads are then rinsed sequentially in city water and deionized water. Finally, excess water is removed from the leads.
Claims6
A method of removing oxides from the surface of the metal leads that extend from a packaged semiconductor integrated circuit device, the method comprising the steps of:
- a. exposing the leads to a fifty percent solution of sulfuric acid;
- b. rinsing the leads with city water;
- c. exposing the leads to a solution consisting of about fifty percent sulfuric acid, twenty-five percent nitric acid and twenty-five percent deionized water;
- d. sequentially rinsing the leads in city water and deionized water;
- and
- e. removing water from the leads.
A method of removing oxides from the surface of metal leads, wherein the leads extend from a packaged semiconductor integrated circuit device, the method comprising the sequential steps of:
- a. exposing the leads to a fifty percent solution of sulfuric acid at about 150.degree. F. for about 10-30 seconds;
- b. rinsing the leads with city water;
- c. exposing the leads to a solution consisting of about fifty percent sulfuric acid, twenty-five percent nitric acid and twenty-five percent deionized water;
- d. sequentially rinsing the leads in city water, deionized water and deionized water at about 135.degree. F.;
- and
- e. drying the leads.
Dependencies are inferred from the claim text.