Gradient dragout system in a continuous plating line

• US 20020179121A1
• Filed: 07/03/2002
• Published: 12/05/2002
• Est. Priority Date: 10/05/1999
• Status: Active Grant

• Current Assignee: David M. Drew, Eiman A. Hegazi, Paul R. Moehle
• Original Assignee: David M. Drew, Eiman A. Hegazi, Paul R. Moehle
• Inventors: Moehle, Paul R., Drew, David M., Hegazi, Eiman A.
• Granted Patent: US 6,780,253 B2
• Time in Patent Office: Days
• US Class Current: 134/26
• CPC Class Codes: B01B 1/00 Boiling; Boiling apparatus for physical or chemical purposes ; Evaporation in general
• CPC Class Codes: B01B 1/005 Evaporation for physical or chemical purposes; Evaporation apparatus therefor, e.g. evaporation of liquids for gas phase reactions
• CPC Class Codes: C25D 21/18 of electrolytes C25D21/22 takes precedence
• CPC Class Codes: C25D 21/20 of rinse-solutions C25D21/22 takes precedence

Abstract

An enhanced gradient dragout system conserves plating chemicals, including precious metals by providing a series of tanks with cascading rinse solutions having a flow rate controlled by heating the first tank to increase the evaporation rate. A portion of the concentrated solution in the heated tank is returned to the process tank. The system minimizes the requirements for clean rinse water, and the need for emptying contaminated rinse tanks with associated recovery and disposal environmental and cost issues. The low cost system is flexible and the process is adapted to the material and process requirements of the plating line.

Claims

1. An improved chemical dragout rinse system following a chemical process bath in a plating line including;

a series of rinse tanks having an automatic level probe in the first tank in said series of rinse tanks,

a heater in the first tank in said series of rinse tanks,

a clean water source for supplying the final tank in said series of rinse tanks, and

a means for passing solution from the final tank into the previous tank, and each of the other tanks feeds the previous tank to maintain a constant solution level in each tank.

2. A system as in claim 1 further including a connection mechanism between the first tank in said rinse series and a preceding chemical process bath.

3. A system as in claim 1 including means for controlling the temperature of the first rinse tank is responsive to the temperature of the preceding chemical process bath.

4. A system as in claim 1 for recovery of dragout chemicals from a lead frame stock material plating line.

5. A system as in claim 1 wherein five rinse tanks are included in said series of rinse tanks.

6. A system as in claim 1 wherein the solution in one of said rinse tanks has a higher evaporation rate than the others.

7. A process for removing dragout chemical contamination from lead frame stock material in a continuous plating line including the steps of;

passing said stock material through a squeeze or air knife following a chemical processing bath,

immersing said material in a rinse tank heated to a temperature equal to or greater than that of the preceding chemical processing bath, and

transporting said material through a series of rinse tanks having a lower concentration of dragout chemicals in each successive tank.

8. A process as in claim 7 whereby dragout chemicals level reach a fixed concentration in each rinse tank.

9. A process as in claim 7 whereby the flow of clean rinse water introduced to the final tank corresponds to the evaporation rate in the heated tank.

11. A process as in claim 7 wherein the dragout chemical comprises palladium.

12. A process as in claim 7 wherein the dragout chemical comprises silver.

13. A process as in claim 7 wherein the dragout chemical comprises nickel.

14. a process as in claim 7 wherein the temperature of the heated rinse tank is in the range of 100 to 175 degrees F.

10. A process for recovering dragout chemicals from a lead frame stock material plating line by returning a portion of the solution from a heated rinse tank to the process tank.