A low temperature co-fired ceramic assembly (LTCC) with a constraining core to minimize shrinkage of outer ceramic layers during firing. The outer ceramic layers have high density circuit features. A ceramic core includes several ceramic layers. Several via holes are located in the first and second ceramic layers. Several low density circuit features are located on the ceramic layers that make up the core. Outer ceramic layers are placed top and bottom of the ceramic core. The outer ceramic layers have via holes and high density circuit features. The circuit features patterned on the ceramic layers include resistors, capacitors, circuit lines, vias, inductors, or bond pads. The ceramic core is fired first in a furnace. The outer layers are then laminated to the ceramic core and fired. The ceramic core controls the shrinkage rate of the outer ceramic layers during firing allowing higher density circuit features on the outer layers.