A direct-write approach to fabricate high precision resistors is reported. Special attention is paid to the effect of print thickness on the resistance value of buried resistors after a low temperature co-firing process. The results show that the direct-write approach provides a superior line definition and thickness control over a traditional screen printing process. Microstructural analysis indicates that there is an interdiffused layer developed between the resistor material and the low temperature co-fired ceramic substrate. These observations are consistent with electrical measurements which show that resistance increases as the effective cross-sectional area is reduced. The resistance data show that the standard deviations for resistors printed on a 6” × 6” area are 5% and 15% for the direct-write and the screen-printed patterns, respectively.

One of the more intriguing freeform fabrication application areas is the fabrication of bodies with designed microstmctures. While design of reinforced composite microstructures has received much attention, construction of designed porous or cellular structures may have greater technical feasibility and offers attractive practical benefits. Freeform fabrication advantages compared to existing foam and honeycomb fabrication techniques are discussed with emphasis on control over pore size, shape, orientation and distribution including hierarchical and functionally graded pore structures, all in combination with the ability to fabricate near net shape objects of complex geometry. Potential applications include the use of designed surface and bulk porosity to enhance both short and long term fixation of structural metal implants to bone, and lightweighting of aerospace components to approach optimized mass efficiency based on predicted stress distributions within a part. Progress using a stereo/photolithographic fabrication technique to construct designed pore structures in stainless steel bodies is presented. Various techniques used to fabricate fine porosity (size less than a layer thickness), coarse porosity (size greater than a layer thickness), and truss, open cell and honeycomb structures with characteristically high cell volume fraction (i.e., greater than 50 percent) are described.