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Metal stamping
Stamped terminals and electrical contacts
Sierxi makes custom connector terminals, contacts, lugs and bus parts from copper-alloy and steel strip on progressive dies in Suzhou. Parts can be supplied loose or on carrier strip, and insert molded into plastic housings on our 180-ton injection machines. Tolerances to ±0.02 mm, from 1,000 pieces.
Capabilities at a glance
| Part types | Terminals, contacts, lugs, bus bars, solder tabs |
|---|---|
| Materials | Copper alloys incl. C7701 nickel silver, steel, stainless |
| Supply form | Loose or on carrier strip |
| Secondary | Insert molding (180 T), plating via partners |
| Tolerance | ±0.02 mm |
| Minimum order | 1,000 pcs |
Which copper alloy for a terminal?
Terminal material is a trade-off between conductivity, spring properties, formability and cost. The values below are typical published figures for annealed or common tempers and vary with temper; check the mill certificate for your exact grade. C7701 nickel silver is in regular production with us; other alloys are quoted on request.
| Alloy (JIS / UNS) | Conductivity, typical | Spring properties | Typical use |
|---|---|---|---|
| C1100 tough-pitch copper | ~100% IACS | Poor | Bus bars, high-current lugs |
| C2680 brass | ~25–28% IACS | Moderate | Low-cost terminals, solder tabs |
| C5191 phosphor bronze | ~13–15% IACS | Good | Connector contacts with mating cycles |
| C7701 nickel silver | Low, single-digit % IACS | Good, corrosion resistant | Contacts, solderable shields, clips |
Design rules for stamped terminals
- Put the contact surface on the rolled face, not the sheared edge — sheared edges are partly fractured and rougher
- State burr direction so burrs face away from the mating contact and from wire insulation
- Bend across the rolling direction where possible, especially for hard tempers with tight radii
- Keep the inside bend radius at least about equal to thickness for half-hard copper alloys; harder tempers need more
- For parts on carrier strip, agree pilot-hole pitch, carrier width and cut-off position with your crimping or insertion equipment
- Mark critical dimensions — contact height, pin width, true position — so they are measured on every lot
Plating thickness choices
Tin, nickel, silver and gold plating are done by qualified plating partners. The right thickness depends on mating cycles, current and environment. The ranges below are common industry starting points, not our specification — put the value you need on the drawing.
| Plating | Typical thickness | When it is used |
|---|---|---|
| Nickel underplate | ~1–3 µm | Diffusion barrier under tin or gold |
| Bright or matte tin | ~1–5 µm | Solderable, low-cycle contacts |
| Gold flash | ~0.05–0.1 µm | Corrosion protection, few mating cycles |
| Hard gold | ~0.4–1.3 µm | Contacts with many mating cycles |
| Silver | ~2–5 µm | Power contacts and higher current |
Insert molded terminals
When a terminal needs a plastic body, we stamp it and mold it in-house on Sumitomo and Tongyang 180-ton injection machines, so one supplier owns both the metal and the plastic tolerance. Molds are built by partner toolmakers.
For insert molding, keep the terminal on its carrier strip into the mold where possible, add locking features (holes or notches) inside the plastic, and leave enough plastic wall around the metal to avoid cracking.
Loose parts or carrier strip?
Loose terminals suit manual assembly and low volumes. Reeled carrier strip suits automatic crimping, insertion or insert molding and protects contacts from tangling in transit. Reel size, interleaf paper and splice rules are confirmed per project.
Crimp, solder, press-fit or screw terminals?
| Terminal type | How it connects | What matters on the drawing |
|---|---|---|
| Crimp terminal | Wire and insulation barrels crimped onto the wire | Barrel width, wall thickness, serrations; crimp height is set by your applicator |
| Solder terminal / tab | Soldered to a PCB or wire | Solderable plating, pin width and true position |
| Press-fit pin | Pressed into a plated PCB hole | Compliant zone geometry and hole size range |
| Ring or fork lug | Clamped under a screw or stud | Hole size, contact area and current rating |
How terminals are inspected
We run an ISO 9001:2015 quality system. First articles from a new die are measured in full on a vision measuring system. Production lots are inspected by AQL sampling, and features you mark as critical — contact height, pin width or position — are checked at 100% by automated optical inspection. A dimensional report and material certificates (mill test certificates) ship with every lot on request.
Plating and RoHS
Tell us the plating spec and thickness on the drawing. If you need RoHS or REACH declarations for the finished part, ask with your RFQ and we will confirm what documentation can be supplied for that material and plating.
Frequently asked questions
Can you supply terminals on reels?
Yes, terminals can be supplied on carrier strip. Reel size and packing details are confirmed per project.
Do you plate terminals in-house?
No. Plating is done by qualified plating partners; we specify, receive and inspect the plated parts.
Which material should I use for a high-current lug?
Pure copper such as C1100 gives the highest conductivity. Brass or nickel silver trade conductivity for strength or corrosion resistance.
Can you mold the terminal into a plastic housing?
Yes. We insert mold in-house on 180-ton machines; the mold is built by a partner toolmaker.
How are terminal dimensions checked?
On a vision measuring system at first article and by AQL sampling on every lot, with automated optical inspection on critical features.
What is the minimum order?
1,000 pieces. Sample cost and lead time are confirmed per project in the quote.
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