Compliant and hermetic solder seal

• US 6,958,446 B2
• Filed: 04/17/2002
• Issued: 10/25/2005
• Est. Priority Date: 04/17/2002
• Status: Expired due to Fees

• Current Assignee: Avago Technologies Fiber IP Singapore PTE Limited (Broadcom, Inc.)
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Mar, Nancy M., Reynolds, Heidi L., Humpston, Giles, Miller, Daniel J., Trott, Gary R., Ichimura, Yoshikatsu, Nystrom, Michael J.
• Primary Examiner(s): LAM, CATHY FONG FONG
• Application Number:
  US10/124,166
• Publication Number:
  US 20030198428A1
• Time in Patent Office: 1,287 Days
• Field of Search: 257/710, 257729-730, 174/52.3, 174/52.4, 174/50.61
• US Class Current: 174/50.61
• CPC Class Codes: B23K 1/0016 Brazing of electronic components
• CPC Class Codes: B23K 2101/40 Semiconductor devices
• CPC Class Codes: B23K 2103/18 Dissimilar materials
• CPC Class Codes: B23K 2103/52 Ceramics
• CPC Class Codes: B23K 2103/54 Glass
• CPC Class Codes: B23K 2103/56 semiconducting semiconducting devices B23K2101/40
• CPC Class Codes: B23K 35/26 with the principal constituent melting at less than 400 degrees C
• CPC Class Codes: G02B 2006/12104 Mirror; Reflectors or the like
• CPC Class Codes: G02B 6/12 of the integrated circuit kind electric integrated circuits H01L27/00
• CPC Class Codes: G02B 6/3512 the optical element being reflective, e.g. mirror
• CPC Class Codes: G02B 6/3582 Housing means or package or arranging details of the switching elements, e.g. for thermal isolation
• CPC Class Codes: G02B 6/36 Mechanical coupling means G02B6/255, G02B6/42 take precedence
• CPC Class Codes: G02B 6/4248 Feed-through connections for the hermetical passage of fibres through a package wall see provisionally also G02B6/4428

Abstract

A solder joint or seal attaching components having dissimilar coefficients of thermal expansion is made thin (e.g., less than 20 μm and preferably about 5 μm) and of a solder such as an indium-based solder that has a tendency to creep. The solder is toroidal or otherwise shaped to avoid tensile stress in the solder. Axial shearing stress in the solder causes reversible creep without causing failure of the joint or seal. In one embodiment, a toroidal solder seal has a diameter, a footprint, and a thickness in approximate proportions of 5000:200:1.

Claims

1. A solder joint comprising:

first and second components having different coefficients of thermal expansion; and

solder between and attached to the first and second components, wherein the solder has a toroidal shape and surrounds a cavity formed between the first and second components, and the solder is an indium based alloy that is 48% tin by weight.

2. The solder joint of claim 1, wherein the solder has a stress rupture life of less than about 1,000 minutes at an applied stress of 5 MN·

m<sup>−

2</sup> at an operating temperature of the solder joint.

3. The solder joint of claim 1, wherein the toroidal shape is such that thermal expansion of the first and second components fails to cause significant tensile or tangential stress in the solder.

4. The solder joint of claim 3, wherein the solder has a thickness less than 20 μ

m.

5. The solder joint of claim 3, wherein the solder has a thickness no greater than 5 μ

m.

6. The solder joint of claim 1, wherein a footprint of the solder is more than 10 times a thickness of the solder.

7. The solder joint of claim 1, wherein a footprint of the solder is about 200 times a thickness of the solder.

8. The solder joint of claim 1, wherein the solder has a thickness less than 20 μ

m.

9. The solder joint of claim 1, wherein the solder has a thickness no greater than 5 μ

m.

10. A solder joint comprising:

first and second components having dissimilar coefficients of thermal expansion; and

solder between and attached to the first and second components, wherein the solder has a thickness less than 20 μ

m and has a tendency to creep in response to shearing stress caused by thermal expansion of the first and second components, and wherein the solder is an indium based alloy that is 48% tin by weight.

11. The solder joint of claim 10, wherein the solder has a thickness no greater than 5 μ

m.

12. The solder joint of claim 10, wherein the solder has a stress rupture life of less than about 1,000 minutes at an applied stress of 5 MN·

m<sup>−

2</sup> at an operating temperature of the solder joint.