Method for attaching a semiconductor chip in a plastic encapsulant, optoelectronic semiconductor component and method for the production thereof
View Patent ↗A radiation-emitting or -receiving semiconductor chip 9 is soft-soldered for mounting on a leadframe 2 over which a prefabricated plastic encapsulant 5 , a so-called premolded package, is injection-molded. Through the use of a low-melting solder 3 applied in a layer thickness of less than 10 μm, the soldering process can be carried out largely without thermal damage to the plastic encapsulant 5.
1. A method, comprising:
mounting a semiconductor chip on a first surface of a thermally and electrically conductive connector formed entirely of an electrically conductive material and arranged in or on a plastic encapsulant,
wherein the encapsulant comprises a thermoplast material and a filler material and the encapsulant contacts at least a portion of a surface of the connector opposite the first surface;
wherein a connection between the chip and the connector is produced by a soft soldering process using a soft solder material, the soft soldering process taking place at a temperature of between 200° C. inclusive and 260° C. inclusive, and a gold film is deposited on the soft solder material before soldering;
wherein the soft solder material comprises substantially an alloy whose material system has a eutectic composition; and
wherein layers comprising different components of the alloy are applied to said semiconductor chip and/or to said connector.
2. The method of claim 1 , wherein the first surface is a first main surface of the connector and the surface opposite the first surface is a second main surface of the connector.
3. The method of claim 2 , wherein said first and second main surfaces are enveloped by said plastic encapsulant.
4. The method of claim 1 , wherein said plastic encapsulant comprises a duroplast material.
5. The method of claim 1 , wherein said plastic encapsulant is produced by being molded over, particularly injection-molded or compression-molded over, a leadframe and said connector is part of said leadframe.
6. The method of claim 1 , wherein said connector is a metallization layer applied to a plastic encapsulant.
7. The method of claim 1 , wherein said connector is a heat sink embedded in said plastic encapsulant.
8. The method of claim 1 , wherein a solder layer having a thickness of between 1 μm inclusive and 10 μm inclusive is used between said semiconductor chip and said connector.
9. The method of claim 1 , wherein a solder layer having a thickness of between 2 μm inclusive and 5 μm inclusive is used between said semiconductor chip and said connector.
10. The method of claim 1 , wherein the solder material used is composed substantially of pure tin or of an alloy whose principal component is tin.
11. The method of claim 1 , wherein the solder material used is at least one alloy from the group of alloys consisting of AgSn, CuSn, PbSn and InPb or a mixture or layer sequence composed of least two of said alloys.
12. The method of claim 1 , wherein the solder material is applied to said chip before soldering.
13. The method of claim 1 , wherein the solder material is applied to said connector before soldering.
14. The method of claim 1 , wherein said semiconductor chip is attached to said connector with flux before soldering.
15. The method of claim 1 , wherein said semiconductor chip is attached to said connector with solder paste before soldering.
16. The method of claim 1 , wherein a through-type furnace is used for the soldering operation.
17. The method of claim 1 , wherein a heating plate is used for the soldering operation.
18. The method of claim 1 , wherein said plastic encapsulant passes through a washing unit after the soldering process.
19. The method of claim 1 , wherein the filler material further comprises at least one of mineral fillers and TiO 2 .
20. The method of claim 1 , wherein the filler material comprises glass fibers.
21. An optoelectronic semiconductor component, comprising:
a radiation-emitting and/or a radiation-receiving semiconductor chip on a thermally and electrically conductive connector formed entirely of an electrically conductive material and arranged in or on a plastic encapsulant,
wherein the connector comprises a first main surface and a second main surface, the first and second main surfaces being enveloped by the plastic encapsulant;
wherein the plastic encapsulant comprises a thermoplast material and a filler material;
wherein a connecting layer between said semiconductor chip and said connector comprises a soft solder having a composition selected so that the soft solder is configured to undergo a soldering process at a temperature of between 200° C. inclusive and 260° C. inclusive, and a gold film deposited on the soft solder;
wherein the soft solder comprises substantially an alloy whose material system has a eutectic composition; and
wherein the alloy has a composition selected so that layers comprising different components of the alloy are applied to said semiconductor chip and/or to said connector.
22. The optoelectronic semiconductor component of claim 21 , wherein said plastic encapsulant comprises a duroplast material.
23. The optoelectronic semiconductor component of claim 21 , wherein said connector is part of a leadframe that is molded over with said plastic encapsulant, particularly by injection molding or compression molding.
24. The optoelectronic semiconductor component of claim 22 , wherein said connector is a metallization layer applied to said plastic encapsulant.
25. The optoelectronic semiconductor component of claim 22 , wherein said connector is a heat sink embedded in said plastic encapsulant.
26. The optoelectronic semiconductor component of claim 22 , wherein a solder layer having a thickness of between 0.1 μm inclusive and 10 μm inclusive is provided between said semiconductor chip and said connector.
27. The optoelectronic semiconductor component of claim 22 , wherein a solder layer having a thickness of between 0.1 μm inclusive and 5 μm inclusive is provided between said semiconductor chip and said connector.
28. The optoelectronic semiconductor component of claim 21 , wherein said soft solder is composed substantially of pure tin or of an alloy whose principal component is tin.
29. The optoelectronic semiconductor component of claim 22 , wherein said soft solder is substantially an alloy whose material system has a eutectic composition.
30. The optoelectronic semiconductor component of claim 29 , wherein said soft solder is substantially an alloy selected from the group consisting of AgSn, CuSn, PbSn and InPb or a mixture or layer sequence composed of at least two of said alloys.
31. The optoelectronic semiconductor component of claim 22 , wherein said semiconductor chip is attached to said connector in a flip-chip assembly, so that an active epitaxial layer sequence faces said connector.
32. The optoelectronic semiconductor component of claim 31 , wherein said soft solder and a contact layer, particularly a contact metallization of said epitaxial layer sequence, are all that is present between said epitaxial layer sequence and said connector.
33. The optoelectronic semiconductor component of claim 21 , wherein the filler material further comprises at least one of mineral fillers and TiO 2 .
34. The optoelectronic semiconductor component of claim 21 , wherein the filler material comprises glass fibers.
35. A method, comprising:
mounting a semiconductor chip on a first surface of a thermally and electrically conductive connector formed entirely of an electrically conductive material and arranged in or on a plastic encapsulant,
wherein the encapsulant comprises a thermoplast material and a filler material and the encapsulant contacts at least a portion of a surface of the connector opposite the first surface;
wherein a connection between the chip and the connector is produced by a soft soldering process using a soft solder material, the soft soldering process taking place at a temperature of between 200° C. inclusive and 260° C. inclusive;
wherein said semiconductor chip is attached to said connector with flux before soldering; and
wherein said plastic encapsulant passes through a washing unit after the soldering process.