Hot bar soldering
A solar cell module comprises a solar cell die that is soldered to a substrate. The substrate comprises one or more power contacts. A power conductor is soldered to a power contact, thereby electrically coupling the power conductor to the solar cell die. A pre-heat module heats a first side of the substrate at a first area to a first temperature for a first duration. Then, a solder heat source solders a power conductor to a power contact at a second area of the substrate at a second temperature for a second duration. The resulting solder connection at the power conductor is less prone to cold-solder defects. The temperature of the pre-heat module is controlled to promote curing of an RTV sealant used in the manufacture of the solar cell module. The temperature of the solder heat source is controlled to avoid burning and degrading of the RTV sealant.
1. A method of soldering a power conductor to a power contact, the method practiced upon an electronic component module having an electronic component soldered to a substrate at a first area of the substrate and having the power contact at a second area of the substrate, the method comprising:
pre-heating the first area of the substrate to a first temperature for a first duration starting at T0 and ending at T2;
generating heat by a separate heat element in each of two protruding edges of a hot solder module, thereby separately causing the two protruding edges to heat up, wherein the hot solder module includes an open channel between the two edges;
selectively contacting the power conductor with the two protruding edges to solder the power conductor to the power contact at the second area of the substrate at a second temperature for a second duration starting at T1 and ending at T3, wherein the first duration overlaps the second duration such that T0<T1<T2; and
increasing the first temperature during at least a portion of the time that the first duration overlaps the second duration.
2. The method of claim 1 , wherein the electronic component comprises a solar cell die and the electronic component module comprises a solar cell module.
3. The method of claim 1 , wherein pre-heating the first temperature is in a range 90° C. to 120° C.
4. The method of claim 1 , wherein the second temperature is in a range of 215° C. to 245° C.
5. The method of claim 1 , wherein the second temperature is 330° C. and the second duration is 10 seconds.
6. The method of claim 1 , the first temperature is increased to between 150° C. and 170° C. during the at least a portion of the time that the first duration overlaps the second duration.
7. The method of claim 1 , further comprising reducing the temperature at the first area, thereby controllably cooling the substrate, the power contact, the power conductor, and the solder joint of the power contact and the power conductor.
8. The method of claim 1 , wherein the first area comprises a first surface of the substrate.
9. The method of claim 8 , wherein pre-heating the first area of the substrate to a first temperature results in heating of the power contact.
10. The method of claim 1 , wherein soldering the power conductor to the power contact at the second area of the substrate at the second temperature comprises heating a second surface of the substrate.
11. The method of claim 1 , wherein the selection of at least one of the first temperature and the first duration promotes curing of a sealant in the electronic component module.
12. The method of claim 1 , wherein the selection of at least one of the first temperature and the first duration avoids melting and reflow of a sealant in the electronic component module.
13. The method of claim 2 , wherein selectively contacting the power conductor with the two protruding edges includes positioning the hot bar solder module including a hot bar soldering surface and a recessed area, wherein the hot bar solder module is positioned such that the recessed area is over the electronic component and the hot bar soldering surface heats the power contact without contacting the solar cell die.
14. The method of claim 13 , wherein the hot bar solder module further includes a positioning actuator and guide for positioning the hot bar soldering surface in thermal contact with at least one of the power conductor, the power contact, and solder.
15. The method of claim 2 , wherein pre-heating the first area of the substrate includes positioning a pre-heat source beneath the substrate such that the pre-heat source is in thermal contact with the substrate.
16. The method of claim 15 , wherein the pre-heat source spans a location of the power contact on the substrate and for heating the power contact.
17. The method of claim 16 , wherein the pre-heat source includes a plurality of pre-heat source modules, each independently controllable.
18. The method of claim 17 , further comprising retracting the pre-heat source away from an underside of the substrate, wherein the retraction is from within a mount that is configured to receive the electronic component module such that the substrate remains stationary during the positioning and the retraction of the pre-heat source.