Avoiding Late-Stage Failures: The Role of Siloxane-Free V-0 Foams in Electronics

Published by Rogers Corporation
Elastomeric Material Solutions

Having your design for an electronic system fail at the validation stage can be frustrating and costly, especially when the mechanical design is sound and UL94 V-0 requirements have been met. Sometimes the cause of poor bonding, or failing contacts and sensors isn't obvious.

In some cases, late-stage failures related to poor bonding, inconsistent wetting, or unreliable sensor performance are not caused by the design or process error. They actually trace back to surface contamination.

One common but often overlooked source of contamination is light silicone oil migration from nearby materials. These issues might not appear during initial builds, but they can quietly risk reliability during qualification testing and long-term use.

Image generated by AI, property of Rogers Corporation.

Why Siloxanes (Light Silicone Oils) Create Risk in Electronics Assemblies

Siloxanes are silicone-based compounds commonly found in lubricants, release agents, adhesives, coatings, and foam materials that are not platinum cured.

The concern doesn’t come from the silicone material itself, but from the low-molecular-weight silicone oils that are present in some formulations. These lightweight oils are mobile and volatile, allowing them to migrate or outgas over time and condense on nearby surfaces.

This obviously causes a problem. Even trace amounts of silicone oil can alter surface energy, interfere with wetting, bonding, and other surface interactions. It is important to talk about how not all silicones carry this risk. Platinum-cured silicones, such as BISCO® HT-800 and BF-1000 materials, don’t generate or release silicone oils during curing or over time. They are a go-to industry choice in electronics when contamination is a concern.

On the other hand, this risk is associated with materials that are not platinum-cured, as light silicone oils may be present.

How Silicone Oil Contamination Shows Up Over Time

When silicone oils migrate and condense on nearby surfaces, the issues tend to develop gradually.

Common downstream effects to look out for:

• Reduced adhesive peel or shear strength
• Wetting defects like fisheyes
• Optical fogging or degraded signal performance
• Inconsistent solderability or adhesion on PCB surfaces

Where This Becomes a Problem in the Design Cycle

Silicone oil–related failures rarely show up during early prototypes or initial design reviews. They are more likely to surface during validation testing, environmental qualification, or long-term reliability assessments.

This timing creates real program risk:

• Root cause identification is slower when contamination is not suspected
• Failures discovered during qualification often require retesting
• Material changes late in development increase cost and delay schedules

For design engineers, the issue is not just about whether a material works on day one, but if it can maintain consistency over time. Uncontrolled contamination variables increase the likelihood of late-stage rework.

Why Siloxane-Free V-0 Polyurethane Foams Reduce Risk

Siloxane-free polyurethane foams help reduce contamination risk by removing a known variable from the system. PORON® 40V0 polyurethane foam is screened for light silicone oils in accordance with ASTM F2466-10 to support use in contamination-sensitive electronics environments.

This allows engineers to meet flame safety requirements without compromising downstream reliability.

Key considerations include:

• UL 94 V-0 compliance: Meets vertical burn requirements commonly specified in electronics, automotive, battery energy storage systems, data centers, and rail applications
• Siloxane-free screening¹: Polyurethane chemistry and material screening mitigate the risk of silicone oil migration in contamination-sensitive assemblies
• Mechanical compliance: Soft, compressible structure accommodates tolerance variation without overstressing components
• Halogen-free formulation²: Produced with non-halogenated flame-retardant materials for compliance with environmental and safety regulations

¹ D3-D10 free per ASTM F2466-10 (non-detected limit = 5 ppm)

² The International Electrotechnical Commission (IEC) defines "halogen-free" materials as those containing less than 900 ppm of chlorine or bromine, and less than 1500 ppm of total halogens, as outlined in standard IEC 61249-2-21.

Importantly, siloxane-free does not require a tradeoff in mechanical or safety performance.

Applications in Which Engineers Specify Siloxane-Free Materials

Siloxane-free polyurethane foams are commonly specified in assemblies that combine flame safety with contamination-sensitive surfaces, including:

• Electronics enclosures with adhesives, surface finishes, or PCBs nearby
• Systems containing optics, sensors, or precision interfaces
• Automotive control modules and interior electronics
• Battery energy storage systems and power electronics

In these environments, the cost of contamination-related failure often exceeds the cost of preventive material selection.

When to Specify a Siloxane-Free Polyurethane

From a design standpoint, siloxane-free materials may be worth specifying when:

• Surface wetting, bonding, or cleanliness affects reliability
• Qualification testing or audits require contamination control
• OEM specifications explicitly call out siloxane-free materials
• Late-stage design changes would carry high cost or risk

In many cases, the real value is avoiding a problem before it shows up at all.

Key Takeaway for Design Engineers

Surface contamination from light silicone oils is a low-visibility risk with high downstream impact. Specifying a siloxane-free, UL 94 V-0 polyurethane foam such as PORON® 40V0 can help eliminate a known failure mechanism without compromising mechanical performance or safety compliance.

Learn more about PORON 40V0 foam or request a sample to evaluate its fit in your next design.

Published on Feb 04, 2026

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