Bumping electronic components using transfer substrates
View Patent ↗A method for forming solder bumps on an electronic component. Providing a transfer substrate having a plurality of solder balls, disposing the transfer substrate on the surface of the electronic component, heating to reflow the solder balls onto the electronic component; and removing the sacrificial substrate. The transfer substrate may comprise a sacrificial film and a metal layer patterned with a mask which is used to form solder balls on the transfer substrate. Or, the transfer substrate may comprise a sheet of silicone rubber having solder balls embedded at least partially in the sheet. A method of aligning a part being bumped with a transfer substrate, using a shuttle mechanism and an alignment film is disclosed.
1. A method for forming solder bumps on an electronic component comprising the steps of:
providing a transfer substrate comprising a sacrificial substrate and plurality of solder balls;
disposing the transfer substrate on the surface of the electronic component;
heating to reflow the solder balls onto the electronic component; and
removing the sacrificial substrate;
wherein:
the sacrificial substrate comprises a sheet of silicone rubber; and
the solder balls are at least partially embedded in the sheet of silicone rubber.
2. The method of claim 1 , wherein:
the transfer substrate comprises a polyimide film covered with a layer of metal.
3. The method of claim 2 , wherein:
the film is Kapton (tin).
4. The method of claim 2 , wherein:
the metal is copper.
5. The method of claim 2 , wherein:
the layer of metal is patterned using a mask.
6. The method of claim 5 , wherein:
the solder balls are formed on the transfer substrate using the mask.
7. The method of claim 1 , wherein:
the solder balls are formed on the transfer substrate using the mask.
8. The method of claim 1 , wherein:
the sacrificial substrate is substantially see-through.
9. The method of claim 1 , further comprising:
prior to heating, urging the transfer substrate against the electronic component.
10. The method of claim 9 , further comprising:
urging the transfer substrate against the electronic component using a pressure plate and a sheet of resilient material disposed between the pressure plate and the transfer substrate.
11. The method of claim 1 , wherein:
the sacrificial substrate is removed before cooling.
12. The method of claim 1 , wherein:
the solder balls are at least 50% embedded in the sheet of silicone rubber.
13. A method of forming a transfer substrate for forming solder bumps on an electronic component comprising the steps of:
providing a blind hole mask having a planar substrate and a plurality of cells extending into a surface of the substrate;
filling the cells with solder paste;
reflowing the solder paste to form solder balls;
encapsulating the mask with silicone rubber;
allowing the silicone rubber to cure, forming a sheet comprising a sacrificial substrate ; and
removing the sacrificial substrate from the mask, with the solder balls least partially embedded therein.
14. The method of claim 13 , wherein:
the solder balls are at least 50% embedded in the sacrificial substrate.