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Thin-Film Modules With Matched Thermal Expansion

IP.com Disclosure Number: IPCOM000061799D
Original Publication Date: 1986-Sep-01
Included in the Prior Art Database: 2005-Mar-09
Document File: 2 page(s) / 37K

Publishing Venue

IBM

Related People

Schmid, GE: AUTHOR

Abstract

Described is a substrate with the thermal expansion of silicon, to which arbitrarily large chips are C4-soldered. Effective expansion of silicon is obtained by clamping a plastic base, supporting the wiring and contact layers, in a solid metal frame. A novel substrate is used to eliminate the stress imposed on the C4 solder joints by the different thermal expansion of the semiconductor material and the substrate. This substrate does not consist of a homogeneous rigid material, such as glass or ceramic, but is made up of a relatively solid frame 1 (Fig. 1A) filled with a preferably cold- curing plastic 3. During filling, the substrate is provided with electrical contact pins 2.

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Thin-Film Modules With Matched Thermal Expansion

Described is a substrate with the thermal expansion of silicon, to which arbitrarily large chips are C4-soldered. Effective expansion of silicon is obtained by clamping a plastic base, supporting the wiring and contact layers, in a solid metal frame. A novel substrate is used to eliminate the stress imposed on the C4 solder joints by the different thermal expansion of the semiconductor material and the substrate. This substrate does not consist of a homogeneous rigid material, such as glass or ceramic, but is made up of a relatively solid frame 1 (Fig. 1A) filled with a preferably cold- curing plastic 3. During filling, the substrate is provided with electrical contact pins 2. The thermal expansion of such a structure is determined mainly by the relatively rigid solid frame 1 and only to a lesser extent by the plastic material 3. The preferably metallic frame 1 should be made of an alloy whose thermal expansion is matched to that of silicon. Such a substrate has the following advantages. -Its expansion is determined mainly by the expansion of metal frame 1 and may be accurately matched to that of silicon by a suitable choice of metal alloy. -The low dielectric constant (of about 3) of the plastic material permits a higher signal propagation speed. -A protective cap 8 (Fig. 1B) may be readily soldered or screwed to metal frame 1. This is a relatively simple and inexpensive method of producing a low dielectric constant, high performance plastic substrate for C4 soldering. Figs. 1A and 1B show an embodiment of the...