Rotating vehicle electrical components such as starters and alternators contain a number of parts that must be soldered into place during the original manufacturing process and in rebuilding.
Both leaded and lead-free solder can be used, but nearly all new OEM vehicles parts today are manufactured using lead-free solders. OEM automotive manufacturers converted to lead-free solders years ago, both to reduce health risks during manufacturing and eliminate lead from possible land-fill disposal. Aftermarket rebuilders can benefit from using lead-free solders as well.
While solder’s main function is as a metal joining material, when used in electronic or electrical components it also must conduct electricity. Alternators generate up to 200 amps and starter motors can exceed 600 amps for commercial units. It’s important to note that Lead is a poor conductor of electricity, but Tin and Silver are much better. In addition, most Tin/Lead alloys have lower melting points than Lead-Free alloys.
Here is a comparison of electrical conductivity and melting points on various solder alloys. Conductivity rates are compared to pure Copper:
|
SOLDER ALLOY |
SOLIDUS °F |
LIQUIDUS °F |
ELECT. COND |
|
10% Tin / 90% Lead |
527 |
576 |
8.2% |
|
60% Tin / 40% Lead |
361 |
372 |
11.5% |
|
63% Tin / 37% Lead |
361 |
361 |
11.6% |
|
96.3% Tin / 3.7% Silver |
430 |
430 |
13.8% |
|
96.5% Tin / 3.0% Silver /0.5Cu |
423 |
426 |
14.9% |
|
97% Tin / 3% Copper |
441 |
590 |
18.1% |
Converting from leaded Solder alloys to lead-free can benefit your operation as follows:
- Field life is increased in some rotating electric parts operating at elevated temperatures and under high amp load.
- Lead contamination issues are reduced
It can be beneficial to use lead-free solder for refurbishing automotive electric parts. It is safer, better for the environment and is even a stronger conductor of electricity.