CAS：935-79-5| The Application of THPA in PCB Ink

Product Name/English Name：cis-1,2,3,6-Tetrahydrophthalic anhydride
English abbreviation：THPA
CAS：935-79-5
Molecular Formula：    C8H8O3
Article No.：S1112
Structural Formula：

Product Introduction
THPA is an important chemical product, mainly used as a curing agent for epoxy resins, a modifier for unsaturated polyester resins and alkyd resins, and an important intermediate in the synthesis of pesticides and pharmaceuticals. In addition, THPA can also be applied to PCB Ink.
Application of THPA
With the improvement and progress of assembly requirements for printed circuit boards, more and more printed circuit boards are requiring plug holes. The ink plugging process for printed circuit boards is a special process that uses screen printing, developed with surface mounting technology (SMT). The circuit board includes various empty holes, except for component insertion holes, installation holes, heat dissipation holes, and test holes, most of the remaining empty holes are not necessarily exposed. Ink plug holes can prevent flux or solder from flowing from the welding surface to the component surface through the empty holes during subsequent component assembly and welding. Military circuit boards, automotive boards, etc. are required to have no bubbles or cracks. Therefore, it is necessary to develop an ink with strong deep curing ability, high temperature resistance, good toughness, and no cracking during cold and hot cycles. Although the existing ink can be suitable for the mass production needs of printed circuit boards, it is difficult to achieve high temperature non cracking and non hollowing for high demand products such as military circuit boards and automotive boards. Therefore, CN107629545B patent has developed a PCB plug hole ink and its preparation method, which includes a main agent and a curing agent. By weight, the main agent includes 15-25 parts of tetrahydrophthalic anhydride modified bisphenol F-type epoxy acrylate, 10-20 parts of tetrahydrophthalic anhydride modified bisphenol A-type phenolic epoxy acrylate, and 50-60 parts of additives.
Among them:
The solid ester of bisphenol F-type epoxy acrylate modified with tetrahydrophthalic anhydride is 70-100mgKOH/g.
The solid ester of tetrahydrophthalic anhydride modified bisphenol A type phenolic epoxy acrylate is 70-100mgKOH/g.
The additives include 3-5 parts of photoinitiators, 10-35 parts of fillers, 0.1-0.5 parts of dispersants, 0.1-0.5 parts of rheological additives, 1-5 parts of fumed silica, 0.5-1.5 parts of defoamers, 2.5-3.5 parts of divalent esters, and 0.1-0.8 parts of pigments.
The curing agent includes 1-10 parts of E51 epoxy resin, 1-10 parts of phenolic epoxy resin, 1-5 parts of divalent ester, 3-10 parts of triepoxypropyl isocyanurate ester, 5-10 parts of active monomer, 4-5 parts of filler, and 1-2 parts of melamine.
The PCB plug hole ink of the present invention has good high-temperature resistance, and after the plug hole is tested at high temperature, it does not crack or sag.

References
CN107629545B A PCB plug hole ink and its preparation method.