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Poly amic acid system for polyimides

a polyimide and amic acid technology, applied in the direction of electrical equipment, printed circuits, transportation and packaging, etc., can solve the problems of insufficient rapid solvent removal for the xylene/nmp system, and the rate of solvent removal is much faster, etc., to achieve the effect of a large-scale production lin

Inactive Publication Date: 2005-06-09
MEDTRONIC INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a poly amic acid precursor that can be easily removed of solvent in a large scale production line. The poly amic acid precursor includes at least one diamine and at least one dianthydride in a cosolvent blend of tetrahydrofuran and N-methylpyrrolidinone. The poly amic acid precursor may also include at least one inorganic filler selected from the group consisting of mica, silica, calcium carbonate, calcium phosphate, calcium silicate, talc, and a combination therof. The poly amic acid precursor can be heated to form a polyimide. The invention also provides a polyimide laminate including a polyimide layer and a metal foil. The poly amic acid precursor can be easily removed of solvent in a large scale production line.

Problems solved by technology

However, processing on a large scale production line requires that the solvent be removed at rate much faster than what can be achieved when using NMP as a solvent.
Solvent removal for the xylene / NMP system is not rapid enough to be utilized on a large scale production line.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

[0029] Poly amic acid powder (1 g) was dissolved in a cosolvent blend of THF (4 g) and NMP(6 g). The ratio was increased to a maximum of 90% by weight of THF combined with 10% by weight of NMP. The solution was placed on a stir plate and left at room temperature to stir overnight. The cosolvent blend produced a homogeneous solution that remained homogeneous over a period of 24 hours at room temperature. Storage of the poly amic acid for 6 months in refrigeration, using the cosolvent system, has resulted in the solution remaining homogeneous. The poly amic acid precursor was cast from the cosolvent blend onto copper foil and dried to afford the final polyimide laminate. The residual solvent retentions were about 1-3% when dried using conventional mass production equipment.

example 2

[0030] Poly amic acid powder (1 g) was dissolved in separate cosolvent blends of methylethyl ketone (MEK) (5 g ) / NMP (5 g) and Acetone (4 g) / NMP (6 g). The polymer precipitated out of both the MEK / NMP cosolvent blend and the Acetone / NMP cosolvent blend. Further, poly amic acid powder (1 g) was dissolved in separate cosolvent blends of methoxyethyl ether (MEE) (4 g) / NMP (6 g) and Toluene (4 g) / NMP (6 g). In both the MEE / NMP cosolvent blend and the Toluene / NMP solvent blend the polymer turned to gel and produced a cloudy appearance. The cosolvents described above produced nonhomogeneous solutions.

example 3

[0031] Poly amic acid powder was dissolved in 100% (wt) NMP. The solvent produced a homogeneous solution. The poly amic acid precursor was cast from the solvent onto copper foil and dried to afford the final polyimide laminate. The residual solvent retentions were about 30-35% when dried using conventional mass production equipment. Repeating the drying schedule reduced the solvent retention to about 28% resulting in the need for a secondary processing stage to remove the solvent.

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Abstract

A poly amic acid precursor containing a combination of tetrahydrofuran and N-methylpyrrolidinone as cosolvents is described. Utilizing the combination of tetrahydrofuran and N-methylpyrrolidinone allows for the removal of significant portions of the solvent during the formation of the polyimide. The removal of tetrahydrofuran and N-methylpyrrolidinone can be done without the use of preheating zones so as to allow for the large scale production of polyimide articles.

Description

[0001] The present application is based on U.S. Provisional Application No. 60 / 268,929, filed Feb. 16, 2002, herein incorporated by reference in its entirety.FIELD OF THE INVENTION [0002] The present invention is directed to a poly amic acid system for polyimides. More particularly, the invention is directed to a poly amic acid solution in a cosolvent blend that is easily removed during the formation of the polyimide. BACKGROUND OF THE INVENTION [0003] Polyimides have proven valuable in the formation of flexible printed circuits. Flexible printed circuits can significantly reduce the weight of the electronics making them important in the portable electronics industry. Flexible printed circuits also reduce the costs associated with assembling the electronics package by reducing the assembly operation and allows for testing of the circuits prior to further assembly. [0004] Typically, a flexible printed circuit is a laminated material that consists of a dielectric layer and a conductor...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C08G73/10H05K1/03
CPCC08G73/1032H05K1/0346C08G73/1042Y10T428/31678Y10T428/31681Y10T428/31721
Inventor SCOTT, LISA
Owner MEDTRONIC INC
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