Ceramic PCB

01

Choose the ceramic for heat, expansion and strength

CeramTec publishes minimum values for its substrate ceramics: aluminium oxide (Al₂O₃) at 500 MPa bending strength, 3.0 MPa√m fracture toughness, CTE 7–9 × 10⁻⁶/K, 24 W/mK thermal conductivity and 15 kV/mm dielectric strength; aluminium nitride (AlN) at 450 MPa, 3.0, 5–6, 170 W/mK and 15 kV/mm; zirconia-toughened alumina (ZTA) at 700 MPa, 3.5, 7–10, 27 W/mK and 25 kV/mm; and silicon nitride (Si₃N₄) at 700 MPa, 6.5, 3–4, 90 W/mK and 25 kV/mm. It calls alumina the best cost/performance ratio, AlN the high-conductivity choice with CTE very close to silicon, and ZTA and Si₃N₄ the options for higher flexural strength and fracture toughness. [1]

CoorsTek's aluminium nitride grades list thermal conductivity of 180, 80 and 150–170 W/m·K, CTE of 5.5–5.6 × 10⁻⁶/°C, dielectric constant of 8.5–9.05 at 1 MHz, flexural strength of 300–375 MPa and volume resistivity above 10¹² to 10¹⁴ Ω·cm, showing how much grade and process change the figures. [4]

Editorial calculation: AlN's 170 W/mK is about 7 times alumina's 24, and Si₃N₄'s 90 about 3.75 times. Through a 0.635 mm substrate under a 1 cm² device, the conduction resistance t ÷ (k × A) is about 0.26 K/W for alumina, 0.07 K/W for Si₃N₄ and 0.04 K/W for AlN, before solder and copper layers are added. [1] [3]

Give the supplier the ceramic and grade, substrate thickness and size, metallisation (thick film, DCB, AMB) with copper or conductor thickness, circuit pattern and minimum line and space, holes and vias, surface finish, power dissipation and required thermal performance, isolation voltage, thermal cycling requirement, flatness and dimensional tolerances, laser scribing or singulation, and quantity.

02

Choose thick-film, DCB or AMB metallisation

Heraeus describes metal ceramic substrates for power electronic modules that carry SiC MOSFETs, Si IGBTs and diodes: the ceramic insulates while the copper conducts current and heat, and their thermal and mechanical properties decide reliability under thermal cycling. Its range includes alumina direct copper bonded (DCB) substrates and silicon nitride active metal brazed (AMB) substrates, including silver-free AMB. [2] CeramTec notes that thick DCB, AMB or SMB copper metallisation spreads heat towards the heat sink. [1]

For printed circuits, CoorsTek writes that “Alumina is the material of choice for most thick-film ceramic substrates”, for hybrid circuits, surface-mount devices and sensors. Its thick-film substrates run from 0.381 mm to 2.54 mm thick (“The most common thicknesses range from 0.635 mm to 1.016 mm”), with minimum hole diameters of 0.381 mm for 0.635–0.889 mm thickness, 0.508 mm for 0.914–1.524 mm and 0.635 mm for 1.549–2.032 mm, in standard sizes from 114.3 × 114.3 mm to 139.7 × 190.5 mm, with laser scribing, machining and edge finishing. [3]

Editorial calculation: 0.635 mm and 1.016 mm are 25 mil and 40 mil, and in each CoorsTek thickness band the minimum hole is about 0.3 to 0.6 times the substrate thickness. [3]

03

Compare what suppliers offer

Suppliers linked to this page list ceramic PCBs; each card links to the page reviewed.

Listings include alumina and AlN thick-film PCBs and heaters, ceramic PCB fabrication with capability pages, and ceramic boards for power modules and thermal management; ask each which ceramic and grade it uses, the metallisation process and copper thickness, and its line, space and hole limits.

04

Trace the ceramic board construction

This is a functional reference built from the sources cited; it is not one maker's specification.

05

Fill the specification fields with values for your board

A ceramic PCB quotation needs values for your board. The table explains each field, gives published values where a reviewed source states them, and says what to obtain from the supplier.

06

Send the ceramic, metallisation and thermal needs together

Paste it into your enquiry below or into an email to a maker, then replace every bracket.

Ceramic: [Al2O3, AlN, ZTA, Si3N4; grade]
Substrate: [thickness; size; holes]
Metallisation: [thick film, DCB, AMB; copper thickness]
Circuit: [line/space; finish]
Thermal: [power; target resistance; cycling]
Electrical: [isolation voltage]
Quantity: [prototype; volume]

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