Method for producing a stable sandwich arrangement of two components with solder situated therebetween

Abstract

A method for producing a stable sandwich arrangement of two components with solder situated therebetween, comprising the steps: (1) providing two components, each having at least one contact surface, and a free solder preform, (2) producing a sandwich arrangement of the components and a solder preform arranged between them and thus not yet connected to them by bringing into contact (i) each one of the contact surfaces, (ii) each of the single contact surface of the components or (iii) one of the contact surfaces of one component and a single contact surface of the other component, with the contact surfaces of the free solder preform, and (3) hot-pressing the sandwich arrangement produced in step (2) so as to form the stable sandwich arrangement at a temperature being at 10 to 40% below the melting temperature of the solder metal of the solder preform, expressed in ° C.

Claims

1. A method for producing a stable sandwich arrangement of two components with solder situated therebetween, comprising the steps of: (1) providing two components, each having at least one contact surface, and a free solder preform made of a solder metal, the solder metal being a tin-rich alloy having a tin content in a range of 90 to 99.5% by weight, (2) producing a sandwich arrangement of the components and a solder preform arranged between them and thus not yet connected to them, by bringing into contact (i) each one of the contact surfaces, (ii) each of the single contact surface of the components or (iii) one of the contact surfaces of one component and a single contact surface of the other component, with the contact surfaces of the free solder preform, and (3) hot-pressing the sandwich arrangement produced in step (2) so as to form the stable sandwich arrangement, wherein the melting temperature of the solder metal of the free solder preform is in a range of 140 to 380° C. and the temperature during the hot-pressing is in a range of 84 to 342° C., the free solder preform has an original thickness of 10 to 500 μm, and a combination of a pressing pressure in a range of 10 to 200 MPa and a pressing time in a range of 1 second to 5 minutes of the hot-pressing step (3) causes a reduction of the original thickness of the free solder preform by ≤10%.

2. The method of claim 1, wherein each of the two components is selected from the group consisting of substrates, active components, and passive components.

3. The method of claim 1, wherein the free solder preform is a solder metal foil, solder metal tape or solder metal plate.

4. The method of claim 1, comprising the further steps: (4) heating the stable sandwich arrangement to a temperature above the melting temperature of the solder metal of the solder joint connecting the two components, and (5) cooling the sandwich arrangement to below the solidification temperature of the molten solder metal, situated between the components, so as to form a braze joint between the components.

5. The method of claim 1, wherein the tin-rich alloy comprises a metal selected from the group consisting of copper, silver, indium, germanium, nickel, lead, bismuth and antimony.

6. The method of claim 1, wherein the tin-rich alloy is lead-free.

7. The method of claim 1, wherein the tin-rich alloy is selected from group consisting of SnAg alloys, SnBi alloys, SnSb alloys, SnAgCu alloys, SnCu alloys, SnSb alloys, InSnCd alloys, InBiSn alloys, InSn alloys, BiSnAg alloys, and SnAgCuBiSbNi alloys.

8. The method of claim 1, wherein the tin-rich alloy is an SnPb alloy or an SnPbAg alloy.

9. A method for producing a stable sandwich arrangement of two components with solder situated therebetween, comprising the steps of: (1) providing two components, each having at least one contact surface, and a free solder preform made of a solder metal, the solder metal being a tin-rich alloy having a tin content in a range of 90 to 99.5% by weight, (2) producing a sandwich arrangement of the components and a solder preform arranged between them and thus not yet connected to them, by bringing into contact (i) each one of the contact surfaces, (ii) each of the single contact surface of the components or (iii) one of the contact surfaces of one component and a single contact surface of the other component, with the contact surfaces of the free solder preform, and (3) hot-pressing the sandwich arrangement produced in step (2) so as to form the stable sandwich arrangement at a temperature being at 10 to 40% below the melting temperature of the solder metal of the free solder preform, wherein a combination of a pressing pressure in a range of 10 to 200 MPa and a pressing time in a range of 1 second to 5 minutes of the hot-pressing step (3) causes a reduction of an original thickness of the free solder preform by ≤10%.

10. The method of claim 9, wherein each of the two components is selected from the group consisting of substrates, active components, and passive components.

11. The method of claim 9, wherein the free solder preform is a solder metal foil, solder metal tape or solder metal plate.

12. The method of claim 9, wherein the original thickness of the free solder preform is 10 to 500 μm.

13. The method of claim 9, wherein the melting temperature of the solder metal of the free solder preform is in the range of 140 to 380° C.

14. The method of claim 9, wherein the melting temperature of the solder metal of the free solder preform is in the range of 140 to 380° C. and the temperature during the hot-pressing is in the range of 84 to 342° C.

15. The method of claim 9, comprising the further steps: (4) heating the stable sandwich arrangement to a temperature above the melting temperature of the solder metal of the solder joint connecting the two components, and (5) cooling the sandwich arrangement to below the solidification temperature of the molten solder metal, situated between the components, so as to form a braze joint between the components.

16. The method of claim 9, wherein the tin-rich alloy comprises a metal selected from the group consisting of copper, silver, indium, germanium, nickel, lead, bismuth and antimony.

17. The method of claim 9, wherein the tin-rich alloy is lead-free.

18. The method of claim 9, wherein the tin-rich alloy is selected from group consisting of SnAg alloys, SnBi alloys, SnSb alloys, SnAgCu alloys, SnCu alloys, SnSb alloys, InSnCd alloys, InBiSn alloys, InSn alloys, BiSnAg alloys, and SnAgCuBiSbNi alloys.

19. The method of claim 9, wherein the tin-rich alloy is an SnPb alloy or an SnPbAg alloy.

Description

INVENTIVE EXAMPLE 1

(1) On the copper surface of a DCB substrate (alumina ceramic, 25 mm×25 mm×380 μm, on both sides on the square surfaces equipped with 300 μm copper), a solder preform (Sn3.5Ag, melting temperature 221° C.; 9 mm×9 mm×0.20 mm) was placed in the middle and a Si-chip (SKCD 81 C 060 I3) fittingly on top of it, and the resulting sandwich arrangement is put between the two plates of a hot presser, preheated to 150° C. (Sinterstar Innovate F-XL of the Boschmann Company). For a period of 60 seconds, a pressing pressure of 100 MPa was applied to the sample.

(2) By means of a MITUTOYO ABSOLUTE Digimatic dial gauge, the thickness reduction of the former solder preform was determined.

(3) The shear strength of the sample was measured by means of a DAGE 4000 plus shear tester of the Nordson Company at a speed of 0.3 mm/s at 20° C.

(4) Examples 2 to 14 were carried out analogously to Example 1.

(5) The following table shows the influences of pressing temperature, pressing time and pressing pressure during hot pressing.

(6) TABLE-US-00002 Re-soldering Pressing Pressing Pressing Thickness Transportability required temperature pressure time reduction (Shear strength >0.1 (shear strength <10 Example (° C.) (MPa) (s) (μm) MPa) MPa) 1 (inv.) 150 100 60 1 yes yes 2 (inv.) 150 100 120 2 yes no 3 (inv.) 150 100 300 5 yes no 4 (inv.) 190 100 60 2 yes no 5 (inv.) 190 100 120 8 yes no 6 (inv.) 190 100 300 22 yes no 7 (inv.) 150 50 120 0 yes yes 8 (not inv.) 150 50 60 0 no — 9 (not inv.) 150 50 10 0 no — 10 (inv.) 150 50 300 2 yes no 11 (inv.) 190 50 120 5 yes no 12 (inv.) 190 50 60 1 yes no 13 (not inv.) 190 50 10 0 no — 14 (inv.) 190 50 300 6 yes no