Thermoplastic
PBT
The connector plastic. Stable, insulating, and it barely takes up water.
Published values for unfilled grades at 23 °C unless stated. Confirm against the supplier datasheet for the grade you specify.
What it is
PBT is a semi-crystalline polyester chosen mainly for electrical parts. It holds its dielectric strength in humid conditions because it absorbs almost no water, and glass-filled grades survive reflow soldering temperatures.
Compared with nylon it is dimensionally stable out of the box, which matters when a connector has to hold pin positions to a tenth of a millimetre.
Where it is used
- Electrical connectors, housings, and switch bodies
- Automotive sensors and ignition components
- Appliance components exposed to heat and moisture
- Motor insulation and bobbins
- Under-bonnet electronics enclosures
Processing notes
Dry 3–4 hours at 120 °C. PBT hydrolyses readily.
Melt 240–265 °C, mold 60–100 °C. It crystallises fast, so fill quickly and gate near thick sections.
Fast crystallisation also means short cycles, which is part of why it is popular for high-volume connectors.
Available through
Design notes
Unfilled PBT warps on flat panels because crystallisation shrinkage is high. Glass fill and correct gating fix it.
Design creep allowance into any snap fit that stays deflected in service.
Weld lines are weak in glass-filled grades. Place gates so they land outside the load path.
Grades and variants
- Unfilled, for insulating parts with modest loads
- GF15–GF30, the standard connector and structural grades
- Flame retardant V-0, halogen free options available
- Impact modified with elastomer phase
- Laser-markable grades for part identification
Specifying this material?
Send your CAD and target volumes. We come back with a price, a lead time, and any material or design notes that would reduce either.