Insulating medium rubber film and production method thereof and multi-layer printed-circuit board

A production method for the insulating medium rubber film comprising a release film and an insulating medium layer arranged on a surface of the release film, a material of the insulating medium layer comprising saturated polyester resin, amino resin or blocked isocyanate, epoxy resin, curing agent, inorganic filler and curing accelerator, the method comprising:

• adding and mixing amino resin or blocked isocyanate to a solution of saturated polyester resin to prepare a first rubber solution;
• adding and mixing epoxy resin and curing agent to the first rubber solution to prepare a second rubber solution;
• adding and mixing inorganic filler and curing accelerator to the second rubber solution to prepare a third rubber solution;
• and
• coating and curing the third rubber solution on the release film to obtain the insulating medium rubber film;
• wherein the material of the insulating medium layer comprises, by weight, 5-30 units of saturated polyester resin, 0.5-3 units of amino resin or blocked isocyanate, 45-75 units of epoxy resin, 1-25 units of the curing agent, 1-100 units of the inorganic filler and 0.1-5 units of the curing accelerator;
• wherein a relative molecular weight of the saturated polyester resin is 8000-30000, and a chemical structural formula of the saturated polyester resin is:
• wherein n is 1-100, R1 and R2 are selected independently from the group consisting of alkyl groups, phenyl groups, naphthyl groups or combination groups thereof, all the functional groups have less than 20 carbon atoms;
• and
• wherein the saturated polyester resin does not contain a polar hydroxyl group in the middle of the saturated polyester resin and only contains a plurality of hydroxyl groups at an end of the saturated polyester resin.

A multi-layer printed-circuit board, the multi-layer printed-circuit board comprising an insulating medium rubber film that comprises:

• a release film and an insulating medium layer arranged on a surface of the release film, a material of the insulating medium layer comprises saturated polyester resin, amino resin or blocked isocyanate, epoxy resin, curing agent, inorganic filler and curing accelerator;
• wherein the material of the insulating medium layer comprises, by weight, 5-30 units of saturated polyester resin, 0.5-3 units of amino resin or blocked isocyanate, 45-75 units of epoxy resin, 1-25 units of the curing agent, 1-100 units of the inorganic filler and 0.1-5 units of the curing accelerator;
• wherein a relative molecular weight of the saturated polyester resin is 8000-30000, and a chemical structural formula of the saturated polyester resin is:
• wherein n is 1-100, R1 and R2 are selected independently from the group consisting of alkyl groups, phenyl groups, naphthyl groups or combination groups thereof, all the functional groups have less than 20 carbon atoms;
• and
• wherein the saturated polyester resin does not contain a polar hydroxyl group in the middle of the saturated polyester resin and only contains a plurality of hydroxyl groups at an end of the saturated polyester resin.