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Because its special characteristics of thick film ceramic PCB, you cannot design that ceramic board following the design rule of FR4. Here are simple design guide for Thick Film Ceramic printed circuit board.

A) About Ceramic PCB Substrate / Raw Material
B) Conductor (metallization), Trace Layer
  • Conductor (metallization) material: Silver Palladium (AgPd), Gold Palladium (AuPd), and Mo/Mu+Nickel plating (for Ozone)
  • Application type: SMD/SMT; Aluminum-Wire Bonding; Gold-wire bonding, Ozone plate. Please advise that information so that different material and thickness will be adopted accordingly
  • Conductor (metallization) layer thickness: >=10um
  • Minimum (Min) Trace Space/Width for volume production:0.30mm & 0.30mm, 0.20mm/0.20mm is also okay but cost will be higher, and 0.15mm/0.20mm only available for prototype.
  • Layers Number: 1L, 2L, Double sided (with PTH), 3L~10L with or without PTH
C) Conductor Resistivity
D) Conductor Power Density
  • The power density for conductor itself should be limited to max 600 Watt/inch2 of conductor surface. And power density for an Al2O3 substrate should be limited to 8 Watts/in2 (for the total of all conductors on top of it)
  • If you have a Ag conductor line of 0.3inch long, 0.010 inch wide (=30 square (0.3/0.01)), the surface area is 0.3 x 0.01 = 0.003 in2. This means the carrying powder P is limited to 600 (power density) x 0.003 (area) = 1.8 watts.
  • Assume conductor resistivity is 6mOhm/sq/12.5um (ESL9562), the resistance value R = 30 sq x 6mOhm = 0.18 ohm.
  • Power = I2 x R, or I2 =Power/R=1.8/0.18 = 10, so the carrying current limit I = 3.16 amps. Or in a short equation: I (amps) = line width (inch) x (power density)1/2 / (sheet resistance, ohm) 1/2
  • If the trace keep 0.3 inch long, but change width to 0.02inch, (=15 square (0.3/0.02), the surface area is 0.3 x 0.02 = 0.006 in2. This means the carrying powder P is limited to 600 (power density) x 0.006 (area) = 3.6 watts.
    And resistance value for that trace will be 15 square x 6mOhm = 0.09 ohm, and then 3.6/0.09= 40, I=6.325 amps.
  • If the trace width keep 0.01inch, but change line to 0.6 inch long (=60 square (0.6/0.01), the surface area is 0.6 x 0.01 = 0.006 in2. This means the carrying powder P is the same as 3.6 watts. (600x0.006).
    But the resistance value for that trace will change to be 60 square x 6mOhm = 0.36 ohm, and then 3.6/0.36= 10, I=3.16 amps. So you can see, it’s no useful to change the trace line.
  • So if you want to have bigger current, then you need to increase the width of trace.
E) Surface finishing:
  • For conductor is AgPd or AuPd, then surface finishing is raw material itself, no extra finishing. For Mo/Mu, then Nickel plating.
F) Bonded Resistors:
  • Different resistor value can be put on the same board, each different resistor period need to set up a new stencil, and can only be printed separately.
  • Resistor can be on the same layer/side, or different layer/side
  • Bonded resistor can support high temperature up to 500C;
  • Please advise temperature coefficient
G) Soldermask
  • It is glass glaze
  • Ceramic PCB can be either with or without soldermask
  • Color: transparent greenish
H) PTH (Plated Through Hole) & NPTH (Non-Plated Through Hole)
I)Manufacturing Tolerance:
  • Board Thickness: +/-10%, Min: +/-0.08mm
  • Outline to Outline: +0.20mm/-0.05mm
  • NPTH: +/-0.05mm
  • PTH: +/-0.10mm
  • NPTH to NPTH: +/-0.05mm
  • PTH to PTH: +/-0.10mm
  • NPTH to edge: +0.15mm/0.05mm
  • PTH to edge: +0.20mm/0.10mm
J) Panel & Shipment:
  • Max panel size: Normal size 138*80mm, and maximum size 200x200mm. Special size also available
  • If board shape is square, rectangle, it can be shipped via both panel and single piece; otherwise, has to be shipped via single piece
  • X-Out board should be allowed for panel delivery
K) Lead Time & Cost
  • Prototype: 2.5-4 weeks
  • Volume production: 3.5-5 weeks for initial order, 2-3 weeks for repeated order, or 1-2 weeks if give us forecast.

Following elements will increased the cost:

  • More hole (PTH or NPTH)
  • Gold Palladium (AuPd) used
  • Different resistor value on same board
  • Big size
  • Big hole
  • PTH expensive than NPTH
  • 0.635mm raw material thickness is the cheapest
You can also click to download Thick Film Design Guide in PDF format.
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