Let’s talk about something that might not cross your mind often but plays a huge role in whether your printed circuit boards (PCBs) work well or fail unexpectedly: outgassing.
Imagine spending weeks designing a board only to discover it degrades over time because of invisible gases seeping from its materials. Frustrating, right? In this guide I’ll break down what outgassing is, why it matters, and how you can keep it in check.
About Me
I’m Frank, a Senior Electronics Engineer based in the USA. Over the years I’ve seen firsthand how small details, like trapped moisture or volatile compounds, can sabotage even the most robust designs.
Today, I’ll share practical tips to help you avoid those hidden pitfalls.
What Exactly Is Outgassing?
Think of that “new car smell”, it’s actually chemicals evaporating from the upholstery. In PCBs, heat or environmental changes force gases and volatile substances out of laminates, solder masks, adhesives or even the substrate. It’s like a sponge releasing water: under heat, trapped moisture and chemicals escape as gas, potentially causing big headaches later on.
Why You Should Care
Outgassing directly impacts reliability:
Heat Exposure
During soldering or lamination, temperatures can soar. If materials aren’t heat-resistant, they release gases that leave residues or weaken layer bonds.
Moisture Absorption
Boards stored in humid conditions soak up water. When reheated, that moisture vaporizes and escapes, risking delamination or solder-joint voids.
Low-Quality Materials
Cheaper resins or masks can outgas even at room temperature. Over months or years, those vapors condense on copper traces, leading to corrosion or electrical leakage.
How Outgassing Sabotages Your PCB
Delamination
Gases escaping between layers prevent proper adhesion, causing layers to peel under stress.
Failed Solder Joints
Residues from outgassed chemicals repel solder, creating voids or cold joints that can fail in the field.
Long-Term Reliability Issues
In sensitive applications, like medical devices or aerospace, even tiny deposits can lead to shorts, leakage or corrosion over time.
Five Simple Ways to Control Outgassing
Select High-Quality Materials
Low-VOC substrates release minimal gases
High-Tg laminates withstand soldering temperatures
Ask your material supplier for standardized outgassing data (e.g., ASTM E595)
Pre-Bake Your Boards
Dry FR-4 or prepreg at around 120 °C for 4–6 hours to drive off residual moisture before assembly.
Optimize Your Process
Reflow profiles: heat gradually so vapors escape before peak temperature
Lamination pressures: apply evenly to avoid trapped air
Test Early and Often
Thermogravimetric Analysis (TGA): measures mass loss under heat
Vacuum tests: simulate harsh environments to detect gas release
Work with a Specialist
I’ve used JLCPCB for critical prototypes, they pre-treat materials and maintain controlled environments to minimize outgassing and ensure boards meet your reliability targets.
Real-World Cautionary Tale
A client once launched a satellite comms board built with a low-cost adhesive. Weeks after deployment, signals dropped, outgassed compounds condensed on antenna surfaces. The solution was switching to a space-grade adhesive and strict pre-bake protocols.
Cutting corners initially ended up costing far more in redesign and relaunch.
Final Thoughts
Outgassing might seem like a minor detail, but in electronics, the devil really is in the details. By choosing the right materials, baking out moisture, fine-tuning your thermal profiles and partnering with experienced manufacturers, you can avoid nasty surprises down the line.
Got questions or a tricky project? Feel free to reach out, I’m always happy to discuss strategies for rock-solid PCB reliability.
Disclaimer: This is educational content and not sponsored.
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