Raw batches for ceramic substrates, substrates produced from the raw batches, and production process of the substrates

A process for the production of a ceramic substrate, which comprises:

• adding a vehicle to a raw batch comprising a mixture of 40 to 80 weight percent of borosilicate glass powder, the borosilicate glass powder comprising, by weight, (a) 65 to 85 percent of silicon dioxide (SiO.sub.2), (b) 5 to 25 percent of boric anhydride (B.sub.2 O.sub.3), (c) 0.1 to 7 percent of at least one component selected from the group consisting essentially of lithium oxide (Li.sub.2 O), sodium oxide (Na.sub.2 O) and potassium oxide (K.sub.2 O), (d) 0.1 to 5 percent of at least one component selected from the group consisting of magnesium oxide (MgO) and calcium oxide (CaO), and (e) 0.1 to 5 percent of alumina (Al.sub.2 O.sub.3), 20 to 60 weight percent of aluminum borate powder which is in the form of fine powder ground to not greater than 3 .mu.m in average particle size, and oxide compound which is at least one component selected from the group consisting of alumina, spinel, cordierite, mullite, forsterite, anorthite and celsian, there being an amount of up to and including 10 weight percent of the oxide compound, and stirring the resultant mixture into a slurry;
• forming the slurry into green sheets;
• forming a circuit pattern on the green sheets and laminating the thus-patterned green sheets;
• and
• calcining the thus-laminated green body at 900.degree..pi.to 100.degree. C.