If you're specifying or assembling cable assemblies with TE Connectivity contacts—particularly the popular Type III+ and Type IV+ pins—you already know a bad crimp can ruin your project. In Q1 2024 alone, I rejected 12% of first deliveries from a new vendor because their crimp height was off by 0.1mm. That quality issue cost us a $22,000 redo and delayed our product launch by three weeks.
This checklist is for engineers, procurement managers, and technicians who need to get it right the first time. Whether you're qualifying a new contract manufacturer or setting up your own bench, these six steps will give you a repeatable process. There's no fluff here—just the steps, the checkpoints, and the one thing almost everyone overlooks.
Before You Start: What You'll Need
This checklist assumes you're working with TE Connectivity contacts (like their 1.0mm, 1.8mm, or 2.5mm pin header terminals) and the appropriate crimp tooling. TE recommends using their CERTI-CRIMP or PRO-CRIMP tools for consistent results, but the process applies to most compatible hand or pneumatic tools.
Three things to have on the bench: the correct contact for your wire gauge, a properly stripped wire, and a calibrated crimp tool. (As of January 2025, TE's engineering recommendations are available on their official product pages; verify your specific part number before starting.)
Step 1: Verify the Contact and Wire Match
This sounds basic. You'd be surprised how often it's skipped.
Before you place a single contact in the tool, confirm two things:
- Wire gauge: Your contact is rated for a specific range (e.g., 22-26 AWG). Using a 24 AWG wire in a contact designed for 18-22 AWG will result in a loose crimp.
- Contact plating: TE offers tin and gold plating. Gold is for high-vibration or high-cycle applications; tin is for general use. Mixing them can cause galvanic corrosion (note to self: check the customer's environmental spec).
Checkpoint: The wire should slide into the contact barrel with slight resistance. If it drops in loose, or if you have to force it, stop. Something's wrong.
Step 2: Strip the Wire to the Correct Length
TE specifies the strip length for each contact—typically around 4-5mm for small pins. Too short, and the conductor won't reach the bottom of the barrel (weak connection). Too long, and exposed conductor will stick out past the insulation support (potential short).
Here's the thing: most people strip just the insulation and assume it's fine. But the conductor strands should be cleanly cut, not nicked. A nicked strand will break under vibration. (Ugh, I've seen this cause intermittent failures on medical equipment.)
Checkpoint: After stripping, inspect the wire under good lighting. All strands should be present and unbroken. The insulation cut should be clean—no frayed edges.
Step 3: Position the Wire in the Contact Correctly
This is the step where most of the poor crimps I've reviewed go wrong. People insert the wire too far, or not far enough, and then crimp anyway.
The conductor should sit flush at the bottom of the contact barrel. The insulation should rest right at the back of the insulation support—not jammed into the conductor barrel. If you push it too far, the insulation gets crimped inside the barrel, creating a weak mechanical grip.
Every spreadsheet analysis pointed to the budget option for this step. Something felt off about their training documentation. Turns out that 'loose on spec' was a preview of 'loose on assembly.'
Checkpoint: Look through the inspection hole on the contact (if present). You should see the conductor through the hole, confirming it's seated correctly.
Step 4: Crimp in the Correct Sequence
TE contacts have a two-step crimp process: first the conductor barrel, then the insulation support. This is not optional.
If you crimp both at once—or worse, crimp the insulation support first—you'll deform the contact. The conductor may not compress evenly, and the insulation support won't grip properly.
Using a ratcheting crimp tool (like the CERTI-CRIMP) handles this automatically. But if you're using a manual hand tool, sequence matters. First squeeze the conductor barrel until full closure. Release, reposition the tool for the insulation barrel, and squeeze.
Checkpoint: After crimping, the insulation support should be wrapped around the insulation without biting into it. The conductor barrel should be evenly compressed—no visible gaps on the seam.
Step 5: Measure the Crimp Height (The One Everyone Ignores)
Here it is. The step most people skip because 'it looks fine.'
TE specifies a crimp height for each contact. For example, a 24 AWG wire in a 1.8mm pin might require a crimp height of 1.6mm ±0.05mm. If you're not measuring, you're guessing.
Even after choosing the new supplier, I kept second-guessing the crimp height. What if their micrometer wasn't calibrated? The two weeks until delivery were stressful. Now every contract includes a specification for crimp height measurement with equipment traceable to NIST.
Use a micrometer with a flat anvil and a ball or pointed spindle (depending on contact shape). Measure at the center of the conductor barrel. The reading must be within spec.
Checkpoint: Record the measurement. If it's out of spec, adjust your tool settings. Do not proceed until it's right.
Step 6: Perform a Pull-Force Test
The ultimate check. Does the crimp hold?
TE provides minimum pull-force values for each contact and wire combination. For a 24 AWG wire on a 1.8mm pin, you might need 12 lbs minimum. Set up your pull tester, clamp the contact, and pull the wire.
If it fails below the minimum force, you have a problem: wrong contact, wrong tooling, wrong technique. Do a root cause analysis before re-crimping.
So glad I implemented this test early in our qualification process last year. Almost skipped it to save time, which would have meant shipping a batch that later failed in the field.
Checkpoint: The failure mode matters too. Ideally, the wire breaks but the crimp holds. If the wire pulls out of the crimp, that's a process issue.
Common Mistakes and How to Avoid Them
I've been reviewing deliverables for over 8 years (since our previous quality manager retired in 2017). Here are the top mistakes I still see:
- Not calibrating the crimp tool: The tool's dies wear over time. TE recommends verification every 6 months or after 5,000 crimps, whichever comes first.
- Using the wrong crimp tool: Not all hand tools are made alike. TE's CERTI-CRIMP tools are designed for specific contact families. Using a generic tool introduces variation.
- Skipping the visual inspection: After crimping, check for damage to the contact body (like bent seams or cracked plating). Even a perfect crimp on a damaged contact is a failure.
- Ignoring the environment: High humidity or salt spray can corrode the crimp joint over time. If your assembly is for an outdoor application, consider a sealed contact or post-crimp coating.
A final thought (disclaimer-style): This checklist reflects my experience as a quality inspector in the industrial electronics space. It's not a substitute for TE's official documentation. Always verify your specific part number against TE's published specifications before production. (Pricing and specifications are current as of January 2025; verify at te.com.)