Vector transient reflow of lead free solder for controlling substrate warpage

1. A method far reflowing solder to interconnect a plurality of electronic components to a substrate, the method comprising:

inserting the substrate into an oven;

preheating the substrate and the plurality of electronic components disposed thereon to a first heating level, wherein the first heating level is maintained for a duration of between 120 and 290 seconds;

preheating the substrate and the plurality of electronic components disposed thereon further to a second heating level, wherein the second heating level is maintained for a duration of between 60 and 180 seconds;

heating the substrate to a peak healing level to reflow the solder using a supplemental heat source positioned within the oven; and

positioning the supplemental heat a distance e above the substrate and providing a supplemental heat source exit having a dimension d and wherein a ratio e/d is less than or equal to fourteen.

2. The method of claim 1 further comprising creating a stream of hot gas using the supplemental heat source, wherein the gas flows transversely across the substrate.

3. The method of claim 2 wherein inserting the substrate into an oven further comprises transporting the substrate through the oven using a conveyor.

4. The method of claim 3 wherein transporting the substrate further comprises moving the substrate through the oven at a speed of between 10 to 50 inches per minute.

5. The method of claim 3 further comprising limiting heat absorption by the substrate to prevent damaging the substrate by adjusting a speed of the conveyor, a distance the supplemental heat source is from the substrate, and a temperature of the gas.

6. The method of claim 1 further comprising providing a gas having a temperature range between 200 to 500 degrees Celsius.

7. A method for reflowing solder to interconnect a plurality of electronic components to a substrate, the method comprising:

inserting the substrate into an oven;

preheating the substrate and the plurality of electronic components disposed thereon to a first heating level, wherein the first heating level is maintained for a duration of between 120 and 290 seconds;

preheating the substrate and the plurality of electronic components disposed thereon further to a second heating level;

heating the substrate to a peak heating level to reflow the solder using a supplemental heat source positioned within the oven;

positioning the supplemental heat a distance e above the substrate and providing a supplemental heat source exit having a dimension d and wherein a ratio e/d is less than or equal to fourteen; and

wherein preheating the substrate further comprises heating the substrate to a second heating level wherein the second heating level has a duration of between 60 to 180 seconds.

8. The method of claim 1 wherein the first heating level is between 130°–160°.

9. The method of claim 7 wherein the second heating level is 190°–230° C.

10. The method of claim 1 wherein the peak healing level is between 230°–280° C.