Stock material or miscellaneous articles – Composite – Of metal
Reexamination Certificate
2003-06-04
2004-09-07
Kiliman, Leszek B (Department: 1773)
Stock material or miscellaneous articles
Composite
Of metal
C428S463000, C428S343000, C548S455000, C558S046000, C558S060000, C560S154000, C564S500000, C568S022000, C568S024000
Reexamination Certificate
active
06787242
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
The invention relates to an adhesion promoter for coatings on metals, a plastic composite body, a compound and a process of preparing a compound, in particular for micro-electronics, which are used for improving the adhesion between metal surfaces and polymers, such as thermosets, deposited thereon and for solving the problem of oxidation of surfaces of metallic bodies or particles.
In particular, in the production of microchips encapsulated with casings, poor adhesion between metal surfaces and polymers frequently causes the problem of premature damage to the microchip. The reason therefor is primarily the difference in the coefficients of thermal expansion of the polymer used for the encapsulation and of the encapsulated metal. On exposure to heat, microcracks often form at the interface between polymer and metal, and can result in failure on further stressing, for example by moisture.
In a failure attributed to an effect known as the “popcorn” effect, water has diffused through the casing to the metal lead frame of the chip, where it accumulates at an interface. On warming of the integrated unit, for example during a soldering operation, the water present at the boundary layer expands, which can result in bursting of the casing.
A further problem is that not all metals used in chip manufacture can be encapsulated with the available polymers. Even fundamental adhesion problems occur in the case of some material combinations.
In order to improve the adhesion between polymers and metals, the prior art discloses using an adhesion promoter or a primer system. Those primers are admixed with the molding composition used to produce the casing. In spite of the slightly improved adhesion, the popcorn effect occurs in the case of those casings.
International Patent Publication WO 90/05303, corresponding to U.S. Pat. Nos. 5,436,161 and 5,242,828, shows the protection of a metallic surface against corrosion using a unimolecular layer of an organic molecule which contains, inter alia, disulfide.
German Published, Non-Prosecuted Patent Application DE 43 33 127 A1 discloses a process for the protection of solderable copper and copper alloy surfaces against corrosion using sulfur compounds.
European Patent Application 0 598 361 A1, corresponding to U.S. Pat. No. 5,455,072, shows a process for the production of a thin diamond film on the surface of a substrate using a unimolecular layer containing monomers. Silanes or thiols are employed for this purpose.
The use of 11-mercapto-1-undecanol for corrosion protection is reported in a paper in the Journal of the Electrochemical Society Vol. 140, No. 2, Feb. 1, 1993, pages 436-443, entitled “Self-Assembled Layers of Alkanethiols on copper for protection against corrosion” by Gi Xue et al. Use of 11-mercapto-1-undecanol as adhesion promoter between a metal and a polymer is not disclosed therein.
UK Patent Application GB 2 299 057 A, corresponding to U.S. Pat. No. 5,598,193, illustrates the treatment of a nozzle plate for inkjet pens with substances which form unimolecular layers. Use of the substances as adhesion promoter between a metal and a polymer is not disclosed therein.
U.S. Pat. No. 3,876,371 shows corrosion protection of steel by using, in particular, phthalocyanines. Use of these substances as adhesion promoter between a metal and a polymer is not disclosed therein.
U.S. Pat. No. 2,371,207 shows corrosion protection of steel by using, for example, sulfur-containing sub-stances having hydrocarbon chains. Use of the substances as adhesion promoter between a metal and a polymer is not disclosed therein.
European Patent Application 0 592 972 A shows metal and semiconductor substrates coated with a resist which can be used in X-ray lithography. A unimolecular adhesion promoter layer of silanes is provided between substrate and resist.
U.S. Pat. No. 5,108,573 illustrates a metallic surface of an electrode which is provided with an electrically conductive polymer film. The polymer film is in the form of a unimolecular layer containing a thiol.
French Patent Application 2 747 685 A1 illustrates a metallic surface of a substrate to which a unimolecular layer containing a silane has been applied. Use of the unimolecular layer as adhesion promoter between a metal and a polymer is not disclosed therein.
UK Patent 1,038,176 shows a razor blade to which a unimolecular layer of stearic acid has been applied. Use of the unimolecular layer as adhesion promoter between a metal and a polymer is not disclosed therein.
German Published, Non-Prosecuted Patent Application 2 342 256 A1, corresponding to U.S. Pat. No. 4,093,780, illustrates the use of thio-glycolates for protection of the surface of zinc against corrosion. Use as adhesion promoter between a metal and a polymer is not disclosed therein.
European Patent Application 0 529 373 A1, corresponding to U.S. Pat. No. 5,347,015, discloses disulfides which are suitable for producing monomolecular and multimolecular layers on precious metal substartes. A use thereof for adhesion improvement is not disclosed.
A paper entitled “Surface Reaction of 2-Mercaptobenimidole on Metals and its Application in Adhesion Promotion”, by Gi Xue, et al. in the Journal of the Electrochemical Society, Vol. 140, No. 2, Feb. 1, 1993, pages 436-443, discloses the use of a 2-mercaptobenzimidazole for adhesion improvement of an epoxy resin of metal. That substance, however, does not have a spacer group in the sense of the invention so that a hydrophobic layer is not created on the coated metal. The known “popcorn effect” is not avoided therewith.
Patent Abstracts of Japan, Publication No. 01159386 illustrates the use of a derivative of 3-Aminopropylsiloxane for forming a corrosion-preventing monomolecular layer on a surface of a heat exchanger made of copper.
Patent Abstracts of Japan, Publication No. 57198269 describes mercaptanes for corrosion-preventing coating of iron plates which are coated with silver.
According to X. H. Gu et al. in “Applied Surface Science” 115, 66 (1997), 3-aminopropyltriethoxysilane is employed as an adhesion promoter for copper and epoxy resin. The dry adhesion of the epoxy resin to copper is increased upon use of that substance. Nevertheless, adhesion problems occur under stress conditions, in particular after moisture weathering and under the influence of high temperatures.
Finally, it is known that metallic bodies or particles are frequently exposed to corrosion which prevents their processing, for example in a metallic ceramic. In the case of metallic bodies, oxidation of the surface is additionally undesired.
SUMMARY OF THE INVENTION
It is accordingly an object of the invention to provide an adhesion promoter for coatings on metals, a plastic composite body, a compound, a process of preparing a compound, in particular for micro-electronics, a method of using adhesion enhancing layers, and microelectronic integrated modules including adhesion enhancing layers that overcome the hereinafore-mentioned disadvantages of the heretofore-known materials and processes of this general type. More specifically, it is an object of the invention to provide substances with which the adhesion of polymers to substances such as metals, for example copper, is improved, even under unfavorable conditions. A further object is to provide substances with which the corrosion of the surfaces of particles and bodies can be prevented or reduced. The invention also has the object of indicating the advantageous use of substances which are already known. A further object is to provide processes for the preparation of such substances. An additional object of the invention is to provide, in particular, correspondingly improved plastic composite articles.
With the foregoing and other objects in view there is provided, in accordance with the invention, an adhesion promoter for a polymer encasing deposited on a surface of a metal body, comprising a monofunctional, bifunctional, or polyfunctional compound having a molecule articulated into at least one first head group and at least one
Atzesdorfer Alexandra
Bauer Friederike
Heckmann Klaus
Möller Rainer
Greenberg Laurence A.
Infineon - Technologies AG
Kiliman Leszek B
Mayback Gregory L.
Stemer Werner H.
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