Formation of fine pitch traces using ultra-thin PAA modified fully additive process
First Claim
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1. A chip on film comprising:
- a flexible dielectric substrate having a first polyamic acid (PAA) anchoring layer on its top surface;
at least one first copper trace on a first Ni—
P seed layer on said first PAA layer and having a surface finishing layer on a top surface of said at least one first copper trace; and
at least one die mounted on said dielectric substrate to said at least one first copper trace.
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Abstract
A method to produce a substrate suitable for diffusion bonding is described. A flexible dielectric substrate is provided. An alkaline modification is applied to the dielectric substrate to form a polyamic acid (PAA) anchoring layer on a surface of the dielectric substrate. A Ni—P seed layer is electrolessly plated on the PAA layer. Copper traces are plated within a photoresist pattern on the Ni—P seed layer. A surface finishing layer is electrolytically plated on the copper traces. The photoresist pattern and Ni—P seed layer not covered by the copper traces are removed to complete the substrate suitable for diffusion bonding.
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Citations
22 Claims
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1. A chip on film comprising:
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a flexible dielectric substrate having a first polyamic acid (PAA) anchoring layer on its top surface; at least one first copper trace on a first Ni—
P seed layer on said first PAA layer and having a surface finishing layer on a top surface of said at least one first copper trace; andat least one die mounted on said dielectric substrate to said at least one first copper trace. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A chip on film comprising:
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a flexible dielectric substrate having a first polyamic acid (PAA) anchoring layer on its top surface and a second PAA layer on its bottom surface; at least one first copper trace on a first Ni—
P seed layer on said first PAA layer and at least one second copper trace on a second Ni—
P seed layer on said second PAA layer wherein said first and second copper traces are interconnected by a first copper via through said dielectric substrate wherein said first copper via further comprises a third PAA layer contacting said dielectric substrate and a third Ni—
P seed layer between said third PAA layer and said first copper via;a first bonding film over said at least one first copper trace and a second bonding film over said at least one second copper trace; an additional flexible dielectric substrate layer on said first and second bonding films and third and fourth at least one copper traces on third and fourth Ni—
P seed layers on third and fourth PAA anchoring layers on said third and fourth additional flexible dielectric substrate layers, respectively, wherein said at least one third and fourth copper traces are interconnected to underlying said first and second at least one copper traces, respectively, by second and third copper vias through said third and fourth additional PI or LCP layers and said first and second bonding layers, respectively, wherein said second and third copper vias further comprise a fourth PAA layer contacting said third and fourth additional flexible dielectric substrate layers and said first and second bonding layers, respectively, and a fourth Ni—
P seed layer between said fourth PAA layer and said second and third copper vias; andat least one die mounted and bonded on a topmost of said at least one third or fourth copper trace. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21, 22)
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Specification