Will It Survive Reflow? Fastener Elements vs 250 °C Profiles
Any fastener that rides a reflow oven brings non-metallic elements into 245–260 °C territory for 60–90 seconds — twice if rework occurs. Material choice decides whether they emerge functional.
Bottom line: for most SMT Fasteners applications the decision comes down to load, environment and assembly method — the SMT Fasteners guide walks through the selection.
The survival table
- Stainless, brass, phosphor bronze: untroubled at any SAC profile.
- FKM (Viton-class) elastomers: fine to ~260 °C peak, the default for reflow-mounted seals.
- Silicone: survives temperature but compresses permanently; acceptable for one-cycle only.
- Nylon 6/6, POM: melt or creep at SAC peak — lead-free reflow ended their reflow career.
- High-temp nylons (PA46, PPS): survive marginal profiles but verify ramp slope, not just peak.
Protective measures
Where the functional element cannot survive reflow, specify removable protection: threaded caps, high-temperature covers, or designs where the element installs after soldering via a snap feature. Design intent should state explicitly which parts see the oven.
Topprecision publishes per-product reflow ratings — peak, ramp and cycle count — on its SMT datasheets, and will run your exact profile on samples before production commitment.
SMT mechanical hardware comparison
| Component | Thread size | Reflow temp | Use |
|---|---|---|---|
| SMT threaded standoff | M2–M4 | 260°C peak | Board stacking, PCIe brackets |
| SMT spring contact | — | 260°C peak | Shielding, ESD grounding |
| SMT screw terminal | M2.5–M4 | 260°C peak | Power grounding, cable attachment |
| Press-fit (post-reflow) | M3–M5 | Post-assembly | Heavy current, service connections |
Need SMT-ready mechanical hardware?
Toprecision supplies SMT threaded standoffs, spring contacts and screw terminals in tape-and-reel packaging, rated for 260°C reflow profiles. Send the PCB thickness and pad layout — we will supply the recommended land pattern and pick-and-place spec. Request SMT hardware consult.
Temperature Limits by Fastener Material
Not all fastener materials survive a 260 °C reflow profile. Tin-lead solder peaks at 220 °C, lead-free SAC305 peaks at 245–260 °C, and selective soldering can locally exceed 280 °C for short durations. Below is a reference table for common fastener materials through 10 reflow cycles:
| Material | Max Peak Temp | Cycles to Degradation | Notes |
|---|---|---|---|
| Stainless 304 / 316 | 300 °C | 50+ | Safe for SAC305 |
| Brass / Copper Alloy | 260 °C | 20–30 | Annealing softens after 10 cycles |
| PEEK / PPS plastic | 250 °C | 5–10 | Glass-fiber filled recommended |
| Aluminum 6061 / 7075 | 200 °C | 5 | Temper softens above 150 °C |
| Nylon 66 | 120 °C | 1 | Do not use in reflow |
