Adhesive die attachment method for a semiconductor die and arrangement for carrying out the method
View Patent ↗The invention relates to an adhesive attaching method for attaching a semiconductor die to a substrate in which an adhesive is deposited onto the substrate, the deposited adhesive is partially cured and/or dried, the partially cured and/or dried adhesive is reheated and a semiconductor die is placed onto the reheated adhesive, after which the adhesive is fully cured so that the semiconductor die is bonded, both electrically and mechanically, to the substrate.
1. An adhesive die attaching method for attaching a semiconductor die to a substrate, the method comprising:
depositing a conductive adhesive onto the substrate;
after depositing the conductive adhesive, partially treating the adhesive by exposing the adhesive to heat;
after partially treating the adhesive, allowing the adhesive to harden;
reheating the hardened adhesive to soften the adhesive;
placing the semiconductor die on the softened adhesive; and
after placing the semiconductor die, fully curing the adhesive, thereby attaching the semiconductor die to the substrate.
2. The method as claimed in claim 1 wherein the step of partially treating the adhesive is carried out by partially curing and/or drying the adhesive.
3. The method as claimed in claim 2 wherein partially treating the adhesive is carried out by subjecting the adhesive to an elevated temperature for a short period of time.
4. The method as claimed in claim 3 wherein partially treating the adhesive is carried out by subjecting the adhesive to a temperature between 25 and 200° C. for 1 to 120 minutes.
5. The method as claimed in claim 1 wherein partially treating the adhesive is performed by heat conduction, heat convection or heat radiation, or a combination thereof.
6. The method as claimed in claim 5 wherein partially treating the adhesive is performed in an oven by placing the substrate carrying the adhesive into the same.
7. The method as claimed in claim 5 wherein partially treating the adhesive is performed by irradiating the adhesive with a laser beam.
8. The method as claimed in claim 1 wherein reheating the adhesive is performed at a temperature of 25 to 300° C. for a duration of 1 second to 30 minutes.
9. The method as claimed in claim 1 wherein placing the semiconductor die onto the adhesive includes the step of pressing the semiconductor die into the adhesive.
10. The method as claimed in claim 9 wherein the pressure applied to the semiconductor die is in the range of 5 to 30 MPa.
11. The method as claimed in claim 1 wherein final curing the adhesive is performed at a temperature of 50 to 300° C. for a duration of 30 to 300 minutes.
12. The method according to claim 1 wherein at least one of a LED, a laser diode and a photo-detector is used as the semiconductor die.
13. The method according to claim 1 wherein a leadframe, a printed circuit board (PCB), a flexible circuit board, or a ceramic, glass or plastic board is used as the substrate.
14. The method according to claim 1 wherein a paste or gel form of the adhesive is used.
15. The method according to claim 1 wherein the conductive adhesive is produced by adding a metallic filler material to a basic material of the adhesive.
16. The method according to claim 15 wherein silver is used as the metallic filler material.
17. The method according to claim 15 wherein silver in the form of flakes is used as the metallic filler material.
18. The method according to claim 15 wherein an epoxy thermoset resin, a thermoplastic resin or silicone is used as the basic material of the adhesive.
19. The method according to claim 18 wherein a one-component epoxy formulation or a two-component epoxy formulation is used as the basic material of the adhesive.