Liquid crystal polymer for flexible circuits

Claim 2

A flexible circuit comprising: a liquid crystal polymer film having solubility in an etchant composition, at temperatures from about 50° C. to about 120° C., said liquid crystal polymer film has through-holes and related shaped voids formed therein using said etchant composition comprising: a solution in water of from about 35 wt % to about 55 wt % of an alkali metal salt; and from about 10 wt % to about 35 wt % of a solubilizer dissolved in said solution.

Claim 3

A flexible circuit according to claim 1 said solution containing from about 40wt. % to about 50wt. % of said alkali metal salt.

Claim 4

A flexible circuit according to claim 1 said etchant composition containing from about 15wt. % to about 30wt. % of said solubilizer.

Claim 5

A flexible circuit according to claim 1 wherein said temperature is from about 70° C. to about 95° C.

Claim 6

A flexible circuit according to claim 1 wherein said alkali metal salt is selected from the group consisting of sodium hydroxide and potassium hydroxide.

Claim 7

A flexible circuit according to claim 1 wherein said solubilizer is ethanolamine.

Claim 8

A flexible circuit according to claim 1 wherein said liquid crystal polymer film has a thickness from about 25 μm to about 125 μm.

Claim 9

A flexible circuit according to claim 1 wherein said liquid crystal polymer film is a multiaxially oriented polymer film.

Claim 10

A flexible circuit according to claim 8 wherein said liquid crystal polymer film is a biaxially oriented polymer film.

Claim 11

A flexible circuit according to claim 1 including at least one unsupported cantilevered lead.

Claim 12

A flexible circuit according to claim 1 including at least one through hole having non-parallel angled sidewalls.

Claim 13

The flexible circuit of claim 11 , wherein said angled sidewalls have an angle from about 25° to about 55°, said angle increasing with concentration of said alkali metal salt from about 35wt. % to about 55wt. % of said etchant.

Claim 14

The flexible circuit of claim 11 , wherein said angled sidewalls have an angle from about 25° to about 35°, when said etchant contains from about 10 wt. % to about 15wt. % of said solubilizer, said angle increasing from about 35° to about 45° when said etchant contains from at out 15wt. % to about 30wt. % of said solubilizer.

Claim 15

A flexible circuit according to claim 1 wherein a through hole forms in said flexible circuit during contact with said etchant composition for a time of about 30 seconds to about 10 minutes.

Claim 16

A flexible circuit according to claim 14 wherein said time is from about 2 minutes to about 7.5 minutes.

Claim 17

A process for etching a pattern in a liquid crystal polymer comprising the steps of: providing a liquid crystal polymer; applying a layer of photoresist to said liquid crystal polymer; exposing the photoresist to a pattern of radiation to crosslink portions of the photoresist exposed to the radiation; removing unexposed photoresist using a developer solution to expose portions of said liquid crystal polymer; and contacting said liquid crystal polymer with an etchant composition comprising: a solution in water of from about 35wt. % to about 55wt. % of an alkali metal salt; and from about 10 wt. % to about 35wt. % of a solubilizer dissolved in said solution to provide said etchant composition for etching said portions of said liquid crystal polymer at a temperature from about 50° C. to about 120° C.

Claim 18

A process for etching a pattern in a liquid crystal polymer comprising the steps of: providing a liquid crystal polymer; applying a layer of photoresist to said liquid crystal polymer; exposing the photoresist to a pattern of radiation to crosslink portions of the photoresist exposed to the radiation; removing unexposed photoresist using a developer solution to expose portions of said liquid crystal polymer; and contacting said liquid crystal polymer with an etchant composition comprising: a solution in water of from about 35wt. % to about 55wt. % of an alkali metal salt; and from about 10 wt. % to about 35wt. % of a solubilizer dissolved in said solution to provide said etchant composition for etching said portions of said liquid crystal polymer at a temperature from about 50° C. to about 120° C.