| US 7,579,134 B2 | ||
| Polyimide composite coverlays and methods and compositions relating thereto | ||
| Thomas Eugene Dueber, Wilmington, Del. (US); Brian C. Auman, Pickerington, Ohio (US); and Kuppusamy Kanakarajan, Dublin, Ohio (US) | ||
| Assigned to E. I. Dupont de Nemours and Company, Wilmington, Del. (US) | ||
| Filed on Mar. 15, 2005, as Appl. No. 11/80,608. | ||
| Prior Publication US 2006/0210819 A1, Sep. 21, 2006 | ||
| Int. Cl. G03F 7/028 (2006.01); G03F 7/032 (2006.01) | ||
| U.S. Cl. 430—283.1 [428/458; 428/473.5; 430/281.1; 430/906; 430/916; 430/926] | 12 Claims |
| 1. A multi-layer composite coverlay substrate, comprising:
A. an adhesive layer having a thickness in a range between and including 1-20 microns, comprising:
i. an adhesive polyamic acid precursor curable to an adhesive polyimide base polymer wherein said adhesive base polymer exhibits
a glass transition temperature (“Tg”) between and including 170° C. and 250° C.;
ii. an ethylenically unsaturated photo-monomer wherein at least 2 percent by weight of the photo-monomer is an amine acrylate,
a methacrylate having amine functionality, or a combination of the two;
B. a cover layer adjacent to the adhesive layer having a thickness between 10 and 75 microns, comprising:
i. 60 to 83.9 percent by weight (on a dry solids basis) cover layer polyamic acid precursor curable to a cover layer polyimide
base polymer having a glass transition temperature (Tg) from 10° C. to 100° C. greater than the glass transition temperature
of the adhesive polyimide base polymer, the cover layer polyamic acid precursor comprising:
a. 95 to 100 mole % diamine component,
b. 85 to 99 mole % dianhydride component,
c. 1 to 15 mol % tetra carboxylic acid wherein the amount of tetracarboxylic acid is based on the amount of corresponding
dianhydride needed to react with the unreacted diamine ends, and wherein the cover layer polyamic acid precursor has a weight-average
molecular weight equal to or below 50,000, and
ii. 15 to 35 percent by weight (on a dry solids basis) an ethylenically unsaturated photo-monomer where at least 2 percent
by weight of the photo-monomer is an amine acrylate, a methacrylate having amine functionality, or a combination of the two;
iii. 1 to 10 percent by weight, on a dry solids basis, of a photo-initiator; and
iv. 0.1 to 1.0 percent by weight (on a dry solids basis) a visible light sensitizer;
wherein the overall in-plane coefficient of thermal expansion (“CTE”), of the coverlay is between 10 and 40 ppm/° C. measured
at 30° C.
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