Liquid crystal polymer film

Abstract

This invention relates to a liquid crystal polymer film for bonding copper foil to achieve an adhesion strength greater than 0.8 kgf / cm. The film has a dielectric loss of less than 0.005 at a frequency of 10 GHz and a relative humidity of 100%, and a coefficient of thermal expansion of 0 to 30 ppm / ℃ at 50 to 200°C. The liquid crystal polymer film comprises a liquid crystal polymer layer and a polyimide layer. The liquid crystal polymer layer has a dielectric loss of less than 0.005 at a frequency of 10 GHz and a relative humidity of 100%, and a coefficient of thermal expansion of 0 to 30 ppm / ℃ at 50 to 200°C. The polyimide layer is disposed above and below the liquid crystal polymer layer, and its dielectric loss is less than 0.005 at a frequency of 10 GHz and a relative humidity of 100%.

Claims

1. A liquid crystal polymer film for bonding copper foil to achieve an adhesion strength greater than 0.8 kgf / cm, the film having a dielectric loss of less than 0.005 at a frequency of 10 GHz and a relative humidity of 100%, and a coefficient of thermal expansion of 0 to 30 ppm / ℃ at 50 to 200℃, comprising: a liquid crystal polymer layer having a dielectric loss of less than 0.005 at a frequency of 10 GHz and a relative humidity of 100%, and a coefficient of thermal expansion of 0 to 30 ppm / ℃ at 50 to 200℃, comprising a liquid crystal polymer and polyimide, wherein the polyimide accounts for 30 to 50% of the weight of the liquid crystal polymer layer; and a polyimide layer disposed above and below the liquid crystal polymer layer, wherein the polyimide layer has a dielectric loss of less than 0.005 at a frequency of 10 GHz and a relative humidity of 100%, and comprises at least a diamine with the following chemical formula.

1. The diamine accounts for 80-96% of the total diamine molar percentage, and dianhydrides, which include 3,3',4,4'-biphenyltetracarboxylic acid dianhydride and bisphenol A type diether dianhydride (BPADA), wherein the 3,3',4,4'-biphenyltetracarboxylic acid dianhydride accounts for 50-74% of the total dianhydride molar percentage, and the bisphenol A type diether dianhydride (BPADA) accounts for 26-50% of the total dianhydride molar percentage.

2. The liquid crystal polymer film as claimed in claim 1, wherein, The thickness of the membrane is 18~60μm.

3. The liquid crystal polymer film as claimed in claim 1, wherein, The liquid crystal polymer layer contains at least insoluble liquid crystal polymer powder and soluble liquid crystal polymer solid. The weight percentage of the insoluble liquid crystal polymer powder in the liquid crystal polymer layer is between 20% and 40%, and its dielectric loss (Df) is less than 0.0008 under the conditions of 10 GHz frequency and 50% relative humidity. The weight percentage of the soluble liquid crystal polymer solid in the liquid crystal polymer layer is between 20% and 40%.

4. The liquid crystal polymer film as claimed in claim 1, wherein, The diamine in the polyimide layer may further include p-phenylenediamine (PDA), with the molar percentage of the diamine in the total diamine molars ranging from 4% to 20%.

5. The liquid crystal polymer film as claimed in claim 1, wherein, The polyimide layer has a thickness between 2 and 8 μm.

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