Electrical-Insulating Flat Washers
Flat insulating washers in Garolite G-10/FR4, mica, ceramic, fiberglass and hard fiber — thicknesses from 0.001" to 0.025", lengths from 1/16" to 11/16", with grades rated from cryogenic service (−250 °F or below) up to 1,000 °F and beyond.
Last updated: 2026-11
Specifications
Where the isolation task is under-head only, the flat insulating washer is the economical part: a simple disc placed between a screw head or nut face and the surface it must not electrically contact. Material selection is the whole decision. Garolite G-10/FR4 — the glass-epoxy laminate of PCB fame — brings high strength and dimensional stability for structural-looking joints that still need isolation. Mica and ceramic take the high-temperature end, with grades rated to 1,000 °F and beyond; fiberglass covers general electrical service; hard fiber is the traditional low-cost insulator. Thicknesses start at 0.001" — shim-grade discs for tight clearances — and run to 0.025". Cryogenic grades are rated to −250 °F and below. RoHS-compliant options are part of the same catalog line, which matters for consumer and automotive electrical builds.
| Function | Insulating disc placed under a screw head or nut face to break electrical contact with the clamped surface |
|---|---|
| Materials | Garolite G-10/FR4, mica, ceramic, fiberglass, hard fiber |
| Thickness band | 0.001"–0.025" across material grades, from shim-grade discs up to structural laminate |
| Length (OD) band | 1/16" through 11/16" across the range |
| Temperature coverage | Grades from −250 °F or below (cryogenic) up to 1,000 °F or greater; most categories cluster below 500 °F |
| Performance options | Electrical insulating, high temperature, flame retardant, moisture resistant grades; RoHS-compliant options |
| Typical applications | PCB and terminal standoff isolation, under-head insulation on painted or anodized surfaces, high-temperature heater and sensor assemblies |
Materials
- Garolite G-10/FR4
- Mica
- Ceramic
- Fiberglass
- Hard fiber
Ordering & documentation
Documents
Shipments are backed by Mill Test Certificate (MTC), Dimensional Report, Salt Spray Test Report on request, with full batch traceability from raw material to finished product. Quality management follows the owner-confirmed compliance list: ISO 9001:2015, RoHS, REACH. Exact document sets are confirmed on the order.
Quotation
- The fastener family (Electrical-Insulating Flat Washers) plus the standard designation from your drawing — DIN / ISO / JIS / ASTM / ANSI, or a drawing for custom parts.
- Size (diameter and length), thread type (metric or inch), property class or grade, and coating or finish.
- Quantity per size and your target delivery date.
- Destination country, and any required documents (for example a mill test certificate) so the quote includes them.
Sample & supply
Minimum order quantity is 10,000 pieces. Stock items run 3–7 days. Quantities or variants outside the standard range are confirmed at quotation.
Storage & shipping
Parts are packed for export and shipped factory-direct to buyers in Europe, Asia, the Americas and the Middle East. Store fasteners dry and protected until installation, and keep coated parts in their packaging until use; specific packing and preservation requirements can be stated on the order and confirmed at quotation.
Frequently asked questions
How do I choose between Garolite, mica and ceramic for an insulating washer?
By the joint's mechanical and thermal demands, in that order. Garolite G-10/FR4 carries real structural load and holds dimensions, so it is the choice when the washer also works as a bearing surface. Mica handles high temperature with the thinner sections — it is the classic 0.001"-class shim insulator for heaters and sensors. Ceramic goes where mica ends: the hottest grades, at the cost of brittleness, so it wants a flat, undisturbed seat and no prying. Fiberglass and hard fiber fill the ordinary middle — general electrical service at commodity cost. Match the temperature grade first, then the load, then pick the thinnest stock that keeps the margin.
What is the MOQ and lead time for this washer type?
The minimum order quantity is 10,000 pieces. Stock items ship in 3–7 days; non-stock items are confirmed at quotation. Common sizes in this washer type are widely stocked; confirm the exact schedule against quantity and size mix at quotation.
Request a Quote
Get factory-direct pricing from the manufacturer.
What to include in your inquiry
- ✓ Standard and property class (e.g. DIN 912, ISO 4762, class 8.8) — or a drawing for custom parts.
- ✓ Sizes, lengths and thread type (metric or inch).
- ✓ Quantity per size and your target delivery date.
- ✓ Destination country, plus any coating or finish requirement.
- ✓ Any documents you need with the shipment (e.g. mill test certificate) so the quote includes them.
- ✓ Your inquiry goes straight to the factory team by email and gets a reply within 24 hours.
- ✓ Factory-direct pricing
- ✓ Standard and custom specifications
- ✓ Factory-direct export to buyers in Europe, Asia, the Americas and the Middle East
- ✓ Full fastener family support