Adhesive-based flex (3-layer) uses acrylic or epoxy to bond copper to polyimide, making it more flexible and economical. Adhesiveless flex (2-layer) directly deposits or laminates copper onto polyimide, offering superior thermal performance and reliability. Choose adhesiveless for high-reliability, fine-pitch, or high-temperature applications; choose adhesive-based for cost-sensitive or high-flex-life applications.
Best Choice
Application Dependent
Adhesiveless construction is preferred for demanding applications where thermal performance, reliability, or fine features are critical. The higher cost is justified by superior performance.
Adhesive-based construction offers good performance at lower cost and can actually provide better flexibility. It's suitable for most commercial applications.
Adhesive layers can be a weak point in demanding environments. Understanding failure modes helps select the right construction.
The manufacturing processes differ significantly, affecting capabilities and cost structure.
We manufacture both adhesive and adhesiveless flex, recommending based on your needs.
Deep knowledge of substrate materials to optimize your design.
We evaluate your thermal requirements to ensure correct construction choice.
We specify adhesiveless only when needed, keeping costs appropriate.
Thermal cycling and reliability testing available for validation.
Construction-specific design rules for optimal manufacturability.
Consider adhesiveless if your application involves: temperatures over 100°C, multiple reflow cycles, fine-pitch components (<0.4mm), high reliability requirements, or thermal cycling. Our engineers can evaluate your specific case.
The acrylic adhesive is softer than polyimide, allowing the structure to bend more easily. However, this advantage decreases at temperature extremes where the adhesive properties change.
Typically no - the entire flex circuit uses one construction type. However, rigid-flex designs can use different constructions in different sections with proper engineering.
Adhesiveless materials cost 20-50% more than adhesive-based. The total board cost increase is typically 15-30% depending on design complexity.
Indicate in your fabrication notes or discuss with us. We'll recommend based on your requirements. If not specified, we'll use adhesive-based for standard applications.