Robust interface bonding with B-staged thermoplastic polyimide adhesive

A method for bonding two surfaces utilizing a heat activated thermoplastic adhesive, said method comprising in combination:

• A. providing a substrate comprising a first of said surfaces;
• and
• B. coating said heat activated thermoplastic adhesive on said substrate, said adhesive comprising in combination:
• i. a solvent;
• and
• ii. a mixture of polyamic-acid polymer and thermoplastic polyimide polymer solids disposed in said solvent, said mixture containing no less than 10% and no greater than 50% thermoplastic polyimide of the total polymer mass and said mixture further containing an amount of solvent of between 20 and 60% of the total mass of the mixture,
• said adhesive forming an adhesive bondline between said surfaces;
• C. providing a second of said surfaces;
• D. positioning the adhesive side of said first surface in contact with said second surface to form an unbonded laminate;
• E. applying heat and pressure to said unbonded laminate to:
• i. outgas said solvent from said adhesive bondline;
• ii. substantially convert all of said polyamic-acid polymer to said thermoplastic polyimide polymer, said conversion generating a quantity of water vapor,
• iii. outgas said water vapor from said adhesive bondline;
• and
• iv. bond said surfaces at the completion of said outgassing.