Custom thick film circuits should be designed with the manufacturing process in mind. A good RFQ package reduces engineering loops, shortens prototype lead time, and prevents avoidable reliability risks.
Design rules to confirm with the manufacturer
Do not assume PCB line and spacing rules apply directly. Thick film design limits depend on substrate, paste, screen, firing process, and inspection criteria. Confirm conductor width, conductor spacing, resistor geometry, dielectric coverage, via or crossover limits, and terminal structure before releasing drawings.
Resistor layout
Provide target resistance, tolerance, TCR, power, trim allowance, and operating temperature. Leave enough area for laser trimming and avoid creating current crowding near terminals or trim cuts.
Thermal path
For heater and power circuits, define voltage, power, heat-up time, working temperature, mounting method, and ambient conditions. Thermal design should include substrate material, conductor heat spreading, and heat sink or housing interface.
Reliability requirements
State whether the product needs humidity testing, thermal cycling, vibration, fuel or oil exposure, insulation resistance, dielectric withstand, aging, or automotive validation.
RFQ checklist
- Drawing files, sample photos, or existing part number.
- Substrate material, size, thickness, and outline tolerance.
- Resistance values, tolerance, TCR, power, and trim method.
- Conductor material preference and terminal requirements.
- Operating voltage, current, temperature, and environment.
- Application: sensor, heater, power module, medical device, RF, or automotive assembly.
- Prototype quantity, mass production estimate, and target lead time.