EP0532898A2
Expired / Lapsed
EP
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Flex tape protective coating
Assignee: International Business Machines Corp
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Filing: 1992-08-10
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Granted: —
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Expires: 2012-08-10
Abstract
Abstract A flexible tape such as TAB or FLEX tape (1) having conducting leads (5) extending in cantilevered fashion over an edge of a dielectric layer (3) preferably a flexible dielectric layer. A photosensitive dielectric coating (2) is disposed on the part of the leads which lie on the dielectric layer. The protective dielectric coating (7) is aligned to the edges of the dielectric layer by a self aligning technique. A liquid polymer is disposed on the dielectric layer. The protective dielectric layer prevents the formation of conductive dendrites bridging adjacent conductors. Without this protection dendrites form between adjacent conductors held at different potentials because of residual water on the dielectric layer which acts as an electrolyte resulting in metal being plated from one line onto another line which builds up as a dendrite which eventually shorts adjacent lines.
Inventors
- 👤 Claudius Feger
- 👤 Teresita Ordonez Graham
- 👤 Kurt Rudolph Grebe
- 👤 Alphonso Philip Lanzetta
- 👤 John Joseph Liutkus
- 👤 Linda Carolyn Matthew
- 👤 Michael Jon Palmer
- 👤 Nelson Russell Tanner
- 👤 Ho-Ming Tong
- 👤 Charles Haile Wilson
- 👤 Helen Li Yeh
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 13:01
CPC Classifications
H; H10; H10W; H10W72/00; H10W72/50; H05; H05K; H05K3/00; H05K3/36; H05K3/361; H05K3/363; H10W70/00; H10W70/40; H10W70/453; H10W70/60; H10W70/67; H10W70/69; H10W72/071; H10W72/075; H10W99/00; H05K2201/00; H05K2201/10; H05K2201/10613; H05K2201/10621; H05K2201/10681; H05K2201/10954; H05K2201/10977; H05K2203/00; H05K2203/17; H05K2203/176; H05K3/0011; H05K3/0017; H05K3/30; H05K3/32; H05K3/34; H05K3/3452; H10W72/90; H10W72/951; H10W72/952; Y; Y10; Y10T; Y10T29/00; Y10T29/49; Y10T29/49002; Y10T29/49117; Y10T29/49121; Y10T29/49124; Y10T29/49155; Y10T29/49165
Claims Analysis
Total Claims: 29
Claim 1
Independent Claim
96 words
A flex product structure comprising: a substrate containing at least one window therethrough and having at least one metal coated metal lead thereon aligned with said window, said lead extending on said substrate from an inner lead area on one edge thereof, to an outer lead area at the opposite edge thereof, said lead at either the inner outer lead area extending in cantilevered fashion over said window in said substrate; a dielectric coating disposed on at least one side of said flex product structure, said dielectric coating being self-aligned to the edges of said window.
Claim 2
Dependent Claim
31 words
The flex product structure defined in claim 1 wherein said substrate contains a plurality of windows at the inner lead area, the outer lead area and in between said lead areas.
Claim 3
Dependent Claim
27 words
The flex product structure defined in claim 1 or 2 wherein said dielectric coating is present over those portions of said flex product structure containing no windows.
Claim 4
Dependent Claim
26 words
The flex product structure defined in any one of the preceding claims wherein said metal lead is selected from the group consisting of copper or aluminum.
Claim 5
Dependent Claim
31 words
The flex product structure defined in any one of the preceding claims wherein said metal coating on said metal lead is selected from the group consisting of gold, tin or aluminum.
Claim 6
Dependent Claim
36 words
The flex product structure defined in any one of the preceding claims wherein said dielectric coating is a polymer that is capable of being etched by a solvent, by a laser or by reactive ion etching.
Claim 7
Dependent Claim
16 words
The flex product structure defined in claim 6 wherein the coating is a low stress material.
Claim 8
Dependent Claim
27 words
The flex product structure defined in claim 6 wherein said coating has tensile modulus times thermal expansion coefficient product value of about 5kPa/ o C or less.
Claim 9
Dependent Claim
64 words
The flex product structure defined in claim 6 wherein the polyimide substrate has a thickness between about 12µm and 125µm, preferably of about 40 µm, copper leads having a thickness less than 125µm, preferably of about 40 µm, a gold thickness of between about 0.25µm and 1.2µm, preferably of about 0.6 µm and a resist thickness less than 125µm, preferably less than 50 µm.
Claim 10
Independent Claim
64 words
A method for making a flex product comprising: securing a metal lead to a substrate, plating a protective metal coating on the exposed areas of said metal lead, applying a photoresist coating, exposing a pattern and developing said pattern to result in selected open areas in said photoresist coating, and and contacting said open areas with an etchant to form openings through said substrate.
Claim 11
Dependent Claim
20 words
The method defined in claim 10 wherein said coating is a photoimageable polymer, preferably polyimide, resistant to the substrate etchant,
Claim 12
Dependent Claim
27 words
The method defined in claim 11 wherein said resist is a partially cyclized poly-cis isoprene containing an average unsaturation of one double bond per 10 carbon atoms.
Claim 13
Independent Claim
74 words
A method for making a flex product comprising: securing a metal lead to a substrate, plating a protective metal coating on the exposed areas of said metal lead, applying a non-imageable coating on the side of the substrate where said leads are located applying a resist on both sides of said substrate, patterning and developing said resist, etching said dielectric coating and said substrate simultaneously to form an opening therethrough and stripping said resist.
Claim 14
Independent Claim
87 words
A method for making a flex product comprising: securing a metal lead to a substrate, plating a protective metal coating on the exposed areas of said metal lead, applying a non-imageable coating on the side of the substrate where said leads are located applying a resist on both sides of said substrate, patterning and developing said resist, etching said dielectric coating with a solvent that does not etch said substrate, then etching said substrate with a solvent suitable to form an opening therethrough and stripping the resist.
Claim 15
Independent Claim
57 words
A method for making a flex product comprising: securing a metal lead to a substrate, plating a protective metal coating on the exposed areas of said metal lead, applying a dielectric coating over said metal coated metal lead, and forming an opening through said substrate and said dielectric coating by ablating selected areas with a laser beam.
Claim 16
Independent Claim
19 words
The method defined in any one of the preceding claims 10 to 15 wherein said metal lead is copper.
Claim 17
Dependent Claim
21 words
The method defined in claim 16 wherein a chromium containing seed layer is positioned between said metal lead and said substrate.
Claim 18
Dependent Claim
71 words
A method of applying a coating to the flex product structure defined in claim 1 comprising preparing a silk screening stencil having the general configuration of a flex product structure to be coated and having openings corresponding to areas of said flex to be coated; aligning said stencil over said flex product structure; screening a suitable coating material through said openings in said screen onto said flex and curing said coating.
Claim 19
Dependent Claim
23 words
The method defined in claim 33 wherein said coating material is a low viscosity polymer, preferably containing a particulate filler in admixture therewith.
Claim 20
Dependent Claim
25 words
The method defined in claim 19 wherein said low viscosity polymer is a silicone containing a particulate filler to increase viscosity to the desired range.
Claim 21
Dependent Claim
22 words
The method defined in claim 18 wherein said coating material is a polymer having a viscosity between about 20,000 and 30,000 cp.
Claim 22
Dependent Claim
22 words
The method defined in claim 19 wherein said coating material is a silicone having a viscosity between about 20,000 and 30,000 cp.
Claim 23
Independent Claim
30 words
The method defined in any one of the preceding claims 18 to 22 wherein a coating is dispensed on all portions of said flex product structure supported by said substrate.
Claim 24
Independent Claim
45 words
The method defined in any one of the preceding claims 18 to 23 wherein said coating has a sufficient viscosity so that it is capable of flowing along the surface of said flex product structure and terminating its flow at the edge of said window.
Claim 25
Independent Claim
42 words
The method defined in any one of the preceding claims 18 to 24 wherein the openings in said silk screen are slightly narrower than the corresponding regions to be coated on said flex product structure to allow for flow of said coating.
Claim 26
Independent Claim
29 words
The method defined in any one of the preceding claims 18 to 25 wherein the difference between said openings and said corresponding regions is between about 20µ and 50µ.
Claim 27
Dependent Claim
109 words
An electronic system comprising a demountable package having a flexible connector suitable for connecting a chip and a card comprising a substrate and having inner and outer metal conducting leads disposed thereon, said flex having a contact pad associated with each said outer lead and adapted to be secured to a metal pad located on said card, said pads being secured in contact with each other by compression means, the improvement comprising a dielectric coating that surrounds and is adjacent to said leads in the outer lead area of said flex when said flex is connected to said card, said coating sealing said outer pad area against dendritic corrosion.
Claim 28
Dependent Claim
27 words
The electronic system defined in claim 27 wherein said outer leads are covered by the dielectric substrate over sites where said leads are bonded to said card.
Claim 29
Dependent Claim
26 words
The electronic system defined in claim 28 wherein the outer lead area is covered by the dielectric substrate to prevent contaminants from entering the bonding sites.
References Cited (Backward Citations)
No citation records indexed.
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