Lokacin da yawan zafin jiki na babban Tg bugu ya tashi zuwa wani yanki, da substrate zai canza daga "glass jihar" zuwa "rubber jihar", da kuma zazzabi a wannan lokaci ana kiransa gilashin canji zafin jiki (Tg) na hukumar.

A wasu kalmomi, Tg shine mafi girman zafin jiki (°C) a cikin abin da substrate ke kula da rashin ƙarfi. Wato, talakawa PCB substrate kayan ba kawai samar da softening, nakasawa, narkewa da sauran abubuwan mamaki a high yanayin zafi, amma kuma nuna wani kaifi ƙi a inji da lantarki halaye (Ina ganin ba ka so ka ga wannan a cikin kayayyakin). .

Gabaɗaya, faranti na Tg suna sama da digiri 130, babban Tg gabaɗaya ya fi digiri 170, kuma matsakaicin Tg yana kusan digiri 150. Yawancin lokaci PCB da aka buga tare da Tg≥: 170 ℃ ana kiran babban Tg bugu. Tg na substrate yana ƙaruwa, kuma za a inganta juriya na zafi, juriya na danshi, juriya na sinadarai, kwanciyar hankali da sauran halaye na allon buga. Mafi girman darajar TG, mafi kyawun juriya na zafin jiki na jirgi, musamman a cikin tsarin da ba shi da gubar, inda manyan aikace-aikacen Tg suka fi yawa. High Tg yana nufin juriya mai zafi.

Tare da saurin haɓaka masana'antar lantarki, musamman samfuran lantarki waɗanda ke wakilta ta kwamfutoci, haɓaka babban aiki da manyan multilayers yana buƙatar juriya mai zafi na kayan aikin PCB azaman garanti mai mahimmanci.

Haɓaka da haɓaka fasahar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakar haɓakawa ta SMT.CMT ta sanya PCBs daɗaɗawa ba za su iya rabuwa da goyan bayan juriya mai zafi mai ƙarfi dangane da ƙaramin buɗe ido, da'ira mai kyau da bakin ciki. Saboda haka, da bambanci tsakanin general FR-4 da high Tg FR-4: shi ne inji ƙarfi, girma da kwanciyar hankali, adhesiveness, ruwa sha, da thermal bazuwar na abu a karkashin zafi jihar, musamman a lokacin da mai tsanani bayan danshi sha. Akwai bambance-bambance a cikin yanayi daban-daban kamar haɓakar thermal, samfuran Tg masu girma a bayyane sun fi kayan aikin PCB na yau da kullun. A cikin 'yan shekarun nan, adadin abokan ciniki da ke buƙatar babban allon buga Tg ya karu kowace shekara.