In the module integration process, lower level packaging elements such as devices, sub-mounts and components are combined as a functional block. Embedded sub-system consists of modules whose operations are controlled by a specific algorithm. Typically, the control algorithm is realized in a form of system software in a processor unit, which controls individual module operations and combines separate module operations as a system operation. In the creation of a cost-efficient embedded system it is essential that reliable, reproducible and cost-efficient building blocks of systems, modules, can be manufactured. We have studied Low Temperature Co-fired Ceramics (LTCC) substrate technology and its possibilities to produce reliable, reproducible and cost-efficient photonic and millimeter wave modules.In this paper we introduce our contribution to the development of LTCC photonic and millimeter wave modules. Most of the papers written on LTCC packaging are in the field of RF and millimeter wave modules and are shortly reviewed in this paper. Photonic modules utilizing LTCC substrates are almost missing in the literature. Several photonic modules based on the use of LTCC substrates developed by our group are introduced in this paper, including hermetic fiber pigtailed power laser, wavelength tunable laser and 10 GBit/s/ch optical interconnects board for photonic applications. In addition, front-end module for 24 GHz transceiver for millimeter wave applications is introduced.