Browse Prior Art Database

Thermal Stress Resistant Solder Reflow Chip Joints

IP.com Disclosure Number: IPCOM000074871D
Original Publication Date: 1971-Jun-01
Included in the Prior Art Database: 2005-Feb-23
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Hamilton, RL: AUTHOR [+3]

Abstract

In joining semiconductor device chips to conductive lands on a ceramic substrate by the reflow of solder balls or pads, which provide both the electrical connection to the conductive lands and mechanical support for the chip, thermal stress on these pad joints may be a problem. The problem is minimized by elongating the solder pads.

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Thermal Stress Resistant Solder Reflow Chip Joints

In joining semiconductor device chips to conductive lands on a ceramic substrate by the reflow of solder balls or pads, which provide both the electrical connection to the conductive lands and mechanical support for the chip, thermal stress on these pad joints may be a problem. The problem is minimized by elongating the solder pads.

The following represents several methods which may be used in achieving such a pad elongation. In method A, step 1 shows a semiconductor chip 10 having a pair of reflowable solder pads 11 and 12 and a central metal mass 13, which melts at a temperature higher than that of pads 11 and 12. Layer 14, which may be glass, is nonwettable by the molten material of the solder pads as well as by mass 13. While mass 13 initially has a lower profile than pads 11 and 12, the dimensions of the wettable exposed surface of the chip 10 adjacent to mass 13 and the volume of mass 13 are such that in the molten state mass 13 will have a higher profile than pads 11 and 12. In step 2, pads 11 and 12 are disposed on land patterns 15 and 16 supported on a ceramic substrate 17. Heat is applied to raise the temperature to the melting point of pads 11 and 12, whereby the molten pads wet lands 15 and 16. Then, in step 3, the temperature is raised beyond the melting temperature of mass 13, causing this mass to press against substrate 17 to cause elongation of the joints formed by pads 11 and 12.

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