A client came to us with a problem that had already cost them two manufacturers and eighteen months of lost time.
Their equipment — a monitoring device installed on offshore platforms in the South China Sea — kept failing. Not after years of service. After months. Sometimes weeks.
The failures were inconsistent. Connectors would work loose. Solder joints would crack under vibration. Some boards showed visible corrosion around the interface pins. Others failed intermittently in ways that took days to diagnose, with symptoms that disappeared when the board was returned to the lab.
They had already switched manufacturers twice. Same design. Same BOM. Same problems.
The client’s question wasn’t about price. It wasn’t about lead time. It was a question we hear from clients who have already tried the usual solutions and failed:
“Can you build a board that actually survives out there?”
This harsh environment PCBA case study is the story of how we approached that question, what we found when we looked beyond the obvious issues, and what we learned about designing for survival — not just for functionality.
Before we could design a solution, we needed to understand exactly what the board was up against. The client gave us their field data, and we spent time on-site to see the operating conditions firsthand.
The platform environment is unforgiving:
The previous boards were designed like indoor electronics. They worked in the lab. They passed factory tests. They failed in the field.
This harsh environment PCBA case study started with a simple observation: what works in a temperature-controlled factory doesn’t necessarily work on a platform exposed to the elements. The gap between lab conditions and field conditions was larger than the client had anticipated.
We did a full failure analysis on the returned boards, sectioning failed units and examining them under microscope and X-ray. The patterns were clear and consistent:
1. Connector pads peeling off the board.
The SMD connector pads were sized per the datasheet recommendation. That recommendation was designed for solderability — not for mechanical stress. The pads were large enough to form a good solder joint during reflow, but not large enough to withstand the mechanical forces of repeated cable connection and disconnection in a high-vibration environment. Over time, the copper pad would lift from the board surface.
2. Solder joint cracking on critical components.
Some components had been designed as SMD to save board space. But SMD joints have significantly less mechanical strength than through-hole joints. Under vibration, cracks developed at the heel of the solder fillet — the point where the solder meets the component lead. These cracks were often invisible to visual inspection.
3. Corrosion at the interface pins.
The conformal coating on the previous boards didn’t extend far enough to cover the connector pin roots. It stopped at the connector body, leaving the exposed pins unprotected. Salt-laden moisture crept in through capillary action and started eating the copper from the inside out.
4. Intermittent failures from thermal cycling.
Temperature swings caused expansion and contraction. Components with different coefficients of thermal expansion (CTE) stressed the solder joints until they micro-cracked. These cracks grew with each thermal cycle, eventually causing open circuits or intermittent connections.
In this harsh environment PCBA case study, the diagnostic phase revealed that the board wasn’t failing for one reason. It was failing for four reasons, and each required a different solution.
We didn’t redesign the entire board. We redesigned the vulnerable points — the places where the previous design had prioritized manufacturability over field reliability.
1. Bigger Pads, More Solder, Better Anchors.
For all connectors and high-stress components, we increased the pad size by 20-25% beyond the datasheet recommendation. More copper area means stronger adhesion to the board substrate. More solder volume means better stress distribution across the joint. Where space allowed, we converted critical connectors from SMD to through-hole. The mechanical strength of a through-hole joint — with solder filling the barrel and forming a fillet on both sides of the board — is an order of magnitude higher than an SMD joint. In vibration testing, the through-hole connectors outlasted the SMD versions by a factor of five.
2. Industrial-Grade Components, Automotive-Grade for Critical Functions.
We replaced all consumer-grade parts with industrial-grade equivalents (temperature range: -40°C to 85°C). For the most critical components — the MCU, power management IC, and communication interface — we upgraded to automotive-grade (AEC-Q100/101/200 certified). We also checked every passive component’s temperature coefficient and voltage rating. Where the original design was running components at 80% of their rated limit, we pushed that down to 50%. Design margin is reliability. In this harsh environment PCBA case study, component selection taught us that the difference between consumer-grade and industrial-grade isn’t just temperature range — it’s also vibration tolerance, humidity resistance, and long-term drift stability.
3. ENIG Finish + Conformal Coating That Actually Covers Everything.
We switched the PCB surface finish from HASL to ENIG (Electroless Nickel Immersion Gold). ENIG provides a flat, oxidation-resistant surface that holds up much better in humid, salt-laden environments. For conformal coating, we used a polyurethane (UR) coating specifically rated for high salt-spray environments. Polyurethane offers excellent chemical resistance and moisture protection, making it the standard choice for harsh environment PCBA case study applications where salt spray is a primary concern. The real change was in how we applied it: we masked and coated the connector pin roots — something the previous manufacturer hadn’t done. The coating now extends all the way to the pin barrel, eliminating the entry point for moisture.
4. Sealing That Doesn’t Age Out in Six Months.
The original design used standard rubber O-rings for the enclosure seal. In the salt-spray environment, they started cracking within six months. We replaced them with fluorocarbon rubber (FKM) seals, which are specifically formulated for high salt and chemical resistance. We also added UV-resistant additives to the enclosure plastic.
5. Testing That Actually Matches the Environment.
We didn’t trust the datasheets. We tested the boards in conditions that matched the field, not the lab. The boards went through salt spray testing (ISO 9227, 48 hours, 5% NaCl solution), thermal cycling (-40°C to 85°C, 500 cycles), vibration testing (random vibration, 5-500 Hz, 2g), and burn-in (72 hours at 70°C, powered). The first test round revealed a weak point in the thermal cycling. We tweaked the stencil design to increase solder volume on that joint and adjusted the reflow profile to improve wetting. The second round passed.
In this harsh environment PCBA case study, the testing phase wasn’t about checking a box. It was about exposing weaknesses before the field could find them.
The client has now run the redesigned boards in the field for over 18 months.
Zero failures related to the previous issues.
The after-sales failure rate dropped from 35% to under 3%. The 3% that did fail were traced to a component that had been substituted during a supply shortage — and that component has since been replaced on the approved parts list. The client has since applied the same design principles to three additional products. Each one has shown similar reliability improvements.
One of their engineers told us: “We spent two years trying to fix this with manufacturing. We should have fixed it with design.”
1. Datasheets are a starting point, not a guarantee.
The previous manufacturer followed the specs exactly. The specs just weren’t written for this environment.
2. Testing doesn’t lie.
Salt spray testing is cheap relative to field failures. Run it early. Run it often.
3. Design margin is reliability.
If you’re running components at 80% of their rated limit in a harsh environment, you’re running them too close to the edge.
4. Small details matter.
Coating coverage, seal material, pad size — these aren’t exciting design decisions. But they’re the decisions that determine whether a board lasts 18 months or 18 days. In this harsh environment PCBA case study, the biggest reliability gains came from the smallest design changes.
If you’re designing for harsh environments — offshore, industrial, outdoor, or anywhere with salt, humidity, vibration, or temperature extremes — the same principles apply.
Don’t design for the lab. Design for where the board will actually live. Test for the conditions you expect, not the conditions you want.
Need help making your PCBA survive harsh conditions? Contact us and we’ll review your design for vulnerabilities — before they become field failures.
