EP0655779A1
Expired / Lapsed
EP
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Method of forming solder bumps on an integrated circuit flip chip
Assignee: Delco Electronics LLC
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Filing: 1994-10-31
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Granted: —
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Expires: 2014-10-31
Abstract
Abstract A method of forming solder bumps (56) for use as terminals of an integrated circuit flip chip encompasses the use of a photoresist (52) which can be selectively patterned (54) with known photoengraving techniques, through which a preformulated solder composition can be accurately and selectively deposited on the surface (50) of the flip chip. A dry film photoresist (52) is used as a mask to apply a solder paste (56), such that precise registration, fine pitch bump arrays, and precise bump size control are possible. Precise control of the composition of the solder bumps (58) is also enabled, which relies on processing techniques which minimise processing costs. The process does not generate chlorofluorocarbons.
Inventors
- 👤 William David Higdon
- 👤 Shing Yeh
- 👤 Ralph Edward Cornell
- 👤 James Arthur Blanton
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 23:28
CPC Classifications
H; H10; H10W; H10W72/00; H10W72/01; H10W72/012; H10W72/20; H10W72/251
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
95 words
A method of forming solder bumps on an integrated circuit flip chip comprising the steps of applying a photoresist film (52) to a surface (50) of an integrated circuit flip chip; forming a pattern in the photoresist film so as to expose portions (54) of the surface, the exposed portions corresponding to locations for solder bumps of the integrated circuit flip chip; printing solder paste through the pattern onto the surface at the exposed portions; heating the solder paste so as to form the solder bumps (58); and stripping the photoresist film from the surface.
Claim 2
Dependent Claim
19 words
A method according to claim 1, wherein the solder bumps (58) form terminals for the integrated circuit flip chip.
Claim 3
Dependent Claim
19 words
A method according to claim 1 or 2, wherein the photoresist film (52) is a CFC-free dry film photoresist.
Claim 4
Dependent Claim
19 words
A method according to claim 3, wherein the dry film photoresist is a negative ultraviolet light-sensitive dry film photoresist.
Claim 5
Dependent Claim
40 words
A method according to claim 3 or 4, wherein the dry film photoresist comprises 25 to 45 weight percent of high-boiling acrylic monomers/oligamers, less than 1 weight percent tetramethyldiaminobenzophenone, and 55 to 75 weight percent colorants, photoinitiators and non-hazardous fillers.
Claim 6
Dependent Claim
19 words
A method according to claim 3, 4 or 5, wherein the dry film photoresist is laminated to the substrate.
Claim 7
Independent Claim
24 words
A method according to any one of claims 3 to 6, wherein a plurality of dry film photoresist layers are applied to the substrate.
Claim 8
Independent Claim
19 words
A method according to any preceding claim, wherein the photoresist film has a thickness of 0.05 to 0.1 millimetres.
Claim 9
Independent Claim
36 words
A method according to any preceding claim, including the step of spacing the exposed portions of surface in the pattern such that adjacent quantities of solder paste are deposited less than substantially 0.4 millimetres apart centre-to-centre.
Claim 10
Dependent Claim
25 words
A method according to claim 9, wherein the spacing between centres of the adjacent quantities of solder paste is as little as substantially 0.2 millimetres.
Claim 11
Independent Claim
16 words
A method according to any preceding claim, wherein the pattern is photoengraved into the photoresist film.
Claim 12
Independent Claim
37 words
A method according to any preceding claim, comprising the step of formulating the solder paste to comprise a mixture of metals, the proportions of metals within the mixture being controlled to be within substantially ±0.1 weight percent.
References Cited (Backward Citations)
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