The surface problem: connectors that fail test
Last April, I spent a week explaining to a supplier why their “perfectly good” connector wasn’t acceptable. The board passed continuity. Impedance looked reasonable. But the product failed temperature cycling, and field units started coming back with intermittent signal issues. This wasn’t a theory from a whitepaper. It was a $22,000 lesson.
The failed part was an N93 jack on a rugged device that gets carried into the field. It reminded me of the arguments I keep hearing about Toughbook vs Dell Rugged laptops. Everyone compares processors, screens, and warranty terms. But what survives a drop is the quality of the small internal connections—the jacks, the cable assemblies, the board-to-board connectors.
If you’re trying to choose between Samtec QSH and Samtec LSHM, I understand. You want to know which has better signal margins, a lower profile, or more robust retention. That’s the question most engineers ask. But it’s not the question that will protect your launch date.
The deeper issue: the connector doesn’t live alone
When I first started in quality, I assumed connector failures came from manufacturing defects. If the part looked straight and continuity passed, I signed off. It took four years and a lot of field failures to realize that most defects are created by design choices long before assembly.
A connector’s datasheet describes its performance in an ideal environment. But you don’t mount it on air. You mount it on a real PCB with vias, anti-pads, return path cutouts, and solder mask. The connector and the PCB launch are one system.
The connector and the PCB launch are one system.
I’m not a signal integrity engineer, so I can’t model that for you. What I can tell you from a quality perspective is this: the same connector can look excellent on one board and unacceptable on another. If you don’t simulate or measure the whole path, you’re relying on hope.
I didn’t always believe this. In my first year, a senior engineer warned me to check via transitions before approving a design. I didn’t listen. The first 50,000-unit build had intermittent opens after thermal cycling. We had to rework the boards, which cost us a quarter and a few gray hairs.
We later found the N93 jack’s problem: solder paste volume. The connector itself was fine. The entire launch wasn’t.
What quality inspection actually catches
In our Q1 2024 quality audit, I rejected 12% of first articles because specifications didn’t match the operational requirement. Not because the parts were cheap, but because “meets datasheet” and “meets your application” are different things.
We inspect to IPC-A-610 Class 3, the acceptance standard for high-reliability electronic assemblies. It’s not a guarantee of signal integrity, but it is the baseline that separates “looks fine” from “will keep working.” That standard catches things like insufficient wetting, cracked solder joints, and damaged plating that functional tests often miss.
This is why comparing Toughbook vs Dell Rugged from the outside can be misleading. A rugged laptop with a tough outer shell can still suffer intermittent failures when the internal board-to-board connectors and jacks aren’t designed for repeated impact. The same logic applies to your board.
The real cost of treating connectors as commodities
Let’s put numbers around it. Our annual order is about 50,000 units. A connector that costs $0.80 more per unit is $40,000. That’s real. But a field failure caused by an unverified transition can cost $22,000 in rework plus a three-week delay, plus the cost of explaining to your customer why they should wait.
On top of that, 8,000 units in storage had to be re-inspected. Every one of them needed a second look because we couldn’t verify which boards had the marginal solder joint. The cheapest connector on the BOM is the most expensive one when it fails.
What I’d do instead
Stop starting with the part number. Start with the signal path.
In my experience, the selection process should look something like this:
- Define the real operating environment: temperature, vibration, shock, humidity, field handling.
- Get the connector manufacturer’s models—including the package footprint and recommended launch—and simulate them in your stack-up.
- Build a small test vehicle before you commit to a full board spin.
- Use inspection criteria that match the reliability level you actually need.
In my work, I’ve seen Samtec QSH and Samtec LSHM families perform well when the board transition was properly engineered. They have published models and design guidance, and that makes verification easier. But I’d say the same thing about any high-speed connector: if someone tells you “this connector is perfect,” they’re not doing you any favors. I’d rather hear “we checked it in your layout.”
From my perspective, the most valuable thing you can do is ask better questions. I’d rather spend ten minutes explaining options than deal with mismatched expectations later. An informed customer asks better questions and makes faster decisions. That’s the whole point.
One caveat: my experience comes from a mid-volume industrial electronics line with about 50,000 units a year. If you’re designing a million-unit consumer product, your cost structure and tolerance for up-front engineering may be different. The failure-cost math still applies.