Harsh Environment Material Case
Harsh Environment Material Case
The customer described the operating environment as a high-altitude substation module, with wide day-night temperature swings and equally pronounced humidity variation.
Those conditions changed the material decision. PA66 was not technically out of specification, but it carried risk in this environment, and we ultimately recommended PBT. The interesting part: after the change, the unit price came down slightly.
The product in this case belongs to our Pluggable Terminal Blocks range.
What the Customer Specified
Rather than naming a material, the customer gave us the operating conditions and requirements:
- Low temperature rating of at least -20°C: the actual environment never reaches -20°C, or even -10°C, but the specification keeps that range
- High temperature rating of at least +100°C: actual operating temperature sits around 55 to 85°C
- UL94 V-0 flammability rating
- Wide humidity variation: day-night temperature swings produce noticeably different humidity between morning and evening
The first two items are worth noting. The specified temperature range sits well beyond actual operating conditions. That margin is deliberate, and a sensible approach where environmental variables run wide.
The Deciding Factor Was Moisture, Not Temperature
On temperature alone, PA66 covers -20 to +100°C without difficulty.
Humidity was the real issue. PA66 has relatively high moisture absorption, and once the material takes on water, its dimensions shift. In a stable environment that matters little. In this application, humidity changed every day.
What mattered more was the combination. Material that has absorbed moisture, then exposed to heat, moves the risk of deformation beyond the theoretical. On a terminal block, deformation means contact stability and clamping reliability are both affected.
PBT absorbs considerably less moisture than PA66, holds dimensional stability better in humid conditions, covers the same temperature range, and is available in grades meeting UL94 V-0.
Our First Recommendation Was LCP
This project took a detour worth explaining.
Our initial recommendation was LCP, not PBT, because at that stage we did not know the customer’s soldering process.
With SMT reflow soldering, the connector body takes a substantial thermal load as the whole assembly passes through the high-temperature zone of the reflow oven. Under those conditions, PBT holding any moisture can deform or blister. This is the same moisture absorption question as before, simply showing up at the process stage instead.
LCP handles heat far better than PBT and is a common choice for reflow applications, which is why it was our first suggestion.
Cost was the obstacle. LCP carries a higher unit price, and the minimum purchase threshold for this class of material also runs higher than PBT. The overall increase clearly exceeded the customer’s budget, and they said so directly.
Once the Process Was Confirmed, the Answer Was Clear
Going back and forth with the customer, we established that this product uses wave soldering rather than reflow.
With wave soldering, the thermal load concentrates on the solder joints at the underside of the board. Both the temperature the connector body sees and the dwell time are far lower than in reflow. The deformation concern with PBT does not apply under this process.
With the process confirmed, PBT became the obvious choice: low moisture absorption, temperature range covered, UL94 V-0 available, and a cost well below LCP.
Three Things Resolved at Once
The environmental issue was addressed. PBT’s low moisture absorption substantially reduces the combined risk of humidity and heat.
Cost went down rather than up. Against the original PA66, PBT came in slightly lower, so the customer solved the environmental problem and improved cost at the same time.
Material availability was never a constraint. PBT is one of our shared materials, already in regular use, with no additional MOQ or lead time involved.
The substitution went on to be approved into the end customer’s BOM.
Documentation the Customer Required
No additional environmental testing was requested on this project.
The reasoning is practical: once the material is settled, the product’s basic characteristics follow from the material specification, and every round of testing carries cost. What the customer asked for was the SGS report and SDS documentation, both of which we provide as standard.
Where a project genuinely needs salt spray, thermal cycling or similar testing, it can be arranged. But with the material clearly defined, most customers start from documentation.
What to Take From This Case
A high-altitude substation is a specific setting, but the sequence of judgments applies to most projects with environmental requirements:
Establish what the environment actually involves, not just the temperature range, but humidity variation, condensation, and any chemical exposure.
Separate the specification from the source of risk. Meeting a temperature rating does not make a material safe. The actual risk may come from moisture absorption, UV exposure, or something else entirely.
Bring the process conditions in from the start. Soldering method and assembly temperature directly bound which materials are viable. Choosing material before confirming process is how projects end up heading the wrong way.
Find the point where specification and cost meet. The highest-performing material is not necessarily the right one. The option that meets the requirement at a workable cost is the one that actually gets implemented.
Who This Applies To
- Equipment operating with wide temperature swings and pronounced humidity variation
- A current material that meets specification on paper, with doubts about real-world performance
- A need to balance environmental resistance against cost, with the trade-off unclear
- Soldering process not yet fixed, with questions about how it affects material choice
- Interest in whether a material substitution could reduce cost as well
Related Products & Technical Resources
If you are currently working on material selection, customization, or special specifications, the following may help:
Custom Specifications & Project Cases | SyncTronics Technology
Electronic Connector Selection & Integration | SyncTronics Technology
Equipment Headed Into a Demanding Environment?
Send us the actual operating conditions and your soldering process, including temperature range, humidity variation, and any safety requirements. SyncTronics will confirm which materials are viable, then provide the corresponding part numbers, documentation, and cost terms.
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