Reduced cycle time manufacturing processes for thick film resistive devices
A process of forming a resistive device such as a load resistor or a heater is provided that includes forming a dielectric layer onto a substrate, a target, or an adjacent functional layer, wherein the dielectric layer in one form defines a single layer of dielectric tape. The dielectric tape is laminated to the substrate, the target, or the adjacent functional layer through a single predetermined cycle of pressure, temperature and time. A resistive layer is formed on the dielectric layer after the dielectric tape is laminated to the substrate. A protective layer is formed over the resistive layer.
1. A process of forming a resistive device comprising:
placing a dielectric layer onto a substrate, the dielectric layer defining a single layer of dielectric tape,
providing an expandable mandrel having a conformable membrane;
completely surrounding the substrate and the single layer of dielectric tape with the conformable membrane;
laminating the dielectric tape on the substrate through a single predetermined cycle of pressure, temperature and time using the expandable mandrel to provide a uniform application of pressure to an outer surface of the dielectric tape, wherein uniform application of pressure causes the dielectric tape to be laminated to the substrate with a uniform thickness and adhesion;
forming a resistive layer on the dielectric layer after the dielectric layer is adhered to the substrate; and
forming a protective layer over the resistive layer.
2. The process according to claim 1 , wherein the conformable membrane is filled with a fluid medium.
3. The process according to claim 2 , wherein the fluid medium is selected from the group consisting of rubber, clay, water, air, oil, and starch-based modeling compound.
4. The process according to claim 1 , wherein the expandable mandrel is elastically conformable.
5. The process according to claim 1 , wherein the resistive layer is formed by a layered process selected from the group consisting of thin film, thick film, thermal spray, and sol-gel.
6. The process according to claim 1 , wherein the protective layer comprises a single layer of dielectric tape, the dielectric tape being laminated to the resistive layer through a single predetermined cycle of pressure, temperature and time.
7. A process of forming a resistive device comprising:
placing a dielectric layer defining a single layer of dielectric tape onto a substrate;
providing an expandable mandrel having a conformable membrane;
completely surrounding the substrate and the single layer of dielectric tape with the conformable membrane;
laminating the dielectric tape on the substrate through a single predetermined cycle of pressure, temperature and time using the expandable mandrel to provide a uniform application of pressure to an outer surface of the dielectric tape, wherein uniform application of pressure causes the dielectric tape to be laminated to the substrate with a uniform thickness and adhesion;
forming a resistive layer on the dielectric layer using a thick film layering process after the dielectric tape is adhered to the substrate; and
laminating a protective layer comprising a single layer of dielectric tape over the resistive layer through a subsequent single predetermined cycle of pressure, temperature and time.
8. The process according to claim 7 further comprising forming conductors in electrical contact with the resistive layer, wherein the conductors are at least partially exposed through the protective layer.
9. The process according to claim 7 , wherein the expandable mandrel is elastically conformable.