# US 2014/0196572 A1 · Soldering process

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- Number: US 2014/0196572 A1
- Document ID: US20140196572A1
- Status: Published application
- Kind: A1
- Application number: 14/083,182
- Filed: 2013-11-18
- Published: 2014-07-17
- Earliest claimed: 2004-04-16
- Assignees: MS2 Technologies, LLC
- Applicants: Ms2 Technologies, LLC
- Inventors: Lawrence C. Kay; Erik J. Severin; Luis A. Aguirre
- Web page: https://patentgrep.com/patent/US20140196572A1

## CPC

- C22B 9/103: {Methods of introduction of solid or liquid refining or fluxing agents}
- B23K 35/262: {Sn as the principal constituent}
- B23K 35/3006: {Ag as the principal constituent}
- B23K 35/3618: {Carboxylic acids or salts}
- B23K 37/047: moving work to adjust its position between soldering, welding or cutting steps (B23K37/053 takes precedence)
- C22B 7/006: {Wet processes}
- C22B 7/04: Working-up slag
- C22B 9/10: with refining or fluxing agents; Use of materials therefor, {e.g. slagging or scorifying agents}(C22B9/18 takes precedence){(C22B9/006 takes precedence)}
- C22B 9/106: {the refining being obtained by intimately mixing the molten metal with a molten salt or slag}
- C22B: PRODUCTION AND REFINING OF METALS (electrolytic C25); PRETREATMENT OF RAW MATERIALS
- B23K: SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM

## Abstract

A process by which molten solder is purified in-situ, making the soldering process more efficient and yielding better results, particularly for lead-free soldering. Lead-free solder becomes practical for use since the temperature for reliable soldering is reduced. A layer of active additive is maintained on the surface of molten solder for scavenging metal oxide from the solder and assimilating metal oxide into a liquid layer. The active additive is an organic liquid having nucleophilic and/or electrophilic groups. As an example, a layer of dimer acid maintained on a wave soldering apparatus scavenges metal oxide from the bath, and assimilates dross that may form on the surface. Scavenging metal oxide cleanses the bath and lowers viscosity of the solder, and PC boards or the like soldered on the wave have reliable solder joints.

## Claims

### Claim 1

A method of processing dross to recover molten solder entrained therein, comprising:
(i) removing dross from a solder-bath, wherein the dross comprises entrained solder,
(ii) placing the dross from (i) in a receptacle,
(iii) adding a liquid active additive comprising a dimer acid mixture to the receptacle containing the dross to form a dross-active additive mixture, wherein the dimer acid mixture comprises a mixture of fatty acid dimers, monomers and trimers, and has an average carbon number in a range of about 24 to 60, and
(iv) heating the dross-active additive mixture from (iii) to thereby assimilate dross in the liquid active additive and release molten solder from the dross.

### Claim 2 (depends on 1)

The method of claim 1, wherein the dross-active additive mixture is stirred during heating.

### Claim 3 (depends on 1)

The method of claim 1, whereby as a result of heating, a pool of released molten solder forms under a layer of the liquid active additive.

### Claim 4 (depends on 1)

The method of claim 1, wherein the dimer acid mixture has an average carbon number in a range of about 28-44.

### Claim 5 (depends on 1)

The method of claim 1, wherein the dimer acid mixture comprises a major portion of dimer acid.

### Claim 6 (depends on 1)

The method of claim 1, wherein the dimer acid mixture comprises a small amount of monomers and trimers.

### Claim 7 (depends on 1)

The method of claim 1, wherein the entrained solder comprises a lead-tin mixture.

### Claim 8 (depends on 1)

The method of claim 1, wherein the entrained solder is a lead-free solder.

### Claim 9 (depends on 1)

The method of claim 1, further comprising (v) recovering the released molten solder.

### Claim 10 (depends on 1)

The method of claim 1, wherein the removing step comprises skimming dross off of a surface of a solder bath.

### Claim 11 (depends on 1)

The method of claim 1, further comprising recovering the liquid active additive comprising assimilated dross.

### Claim 12 (depends on 11)

The method of claim 11, further comprising roasting the recovered liquid active additive comprising assimilated dross.

### Claim 13 (depends on 1)

The method of claim 1, wherein the liquid active additive is a viscous liquid.

### Claim 14 (depends on 1)

The method of claim 1, where in step (iv), the dross-active additive mixture is heated above the melting point of the solder.

### Claim 15 (depends on 1)

The method of claim 1, wherein the dimer acid mixture is prepared from a tall oil feedstock.

### Claim 16 (depends on 5)

The method of claim 5, wherein the dimer acid mixture comprises from about 80-90% fatty acid dimers.