Structural adhesives fixing battery modules
Structural polyurethane adhesives are used to bond cells into modules and modules into the battery tray, holding the entire battery pack firmly against vibration while replacing some of the heavy metal frames and brackets.
In next-generation battery pack designs, especially the cell-to-pack trend, manufacturers are gradually eliminating intermediate module frames. The adhesive layer then does more than bond; it also carries load, contributing to the stiffness of the entire structure.
Why choose PU adhesive for battery modules
Two-component PU adhesive offers a good balance of strength and flexibility. Lap shear strength reaches approximately 8 to 15 MPa on aluminum and film-coated cell casings, while elongation at break remains above 50%. As a result, the bond can absorb the differing thermal expansion of cells and the aluminum tray without cracking.
- Reduces weight by eliminating some bolts, clamping bars and pressure plates.
- Distributes stress evenly over the entire surface instead of concentrating it at fastening points.
- Some grades also offer thermal conductivity of around 1 W/m·K, bonding and dissipating heat at the same time.
- Good electrical insulation with no need for an intermediate liner.
Application challenges
PU adhesive is moisture sensitive, so it must be stored sealed and the shop environment must be controlled. Cell casings are often wrapped in PET film or painted, so plasma treatment or a primer is needed to achieve consistent adhesion. Open time and handling strength time must match the line takt time.
Parameters typically agreed upon with design engineers
- Target bond line thickness and allowable tolerance.
- Time from adhesive dispensing to cell placement and pressing.
- Required strength after 24 hours and after damp heat aging.
- Ease of disassembly for end-of-life recycling.
Structural adhesive for batteries has to be designed alongside the product, not selected after the drawings are finalized. The earlier we get involved, the more we can help customers avoid costly tooling revisions. — AMS Technical Team Lead
Validating bond durability
Bonds are tested through thermal cycling, damp heat at 85 °C and 85% RH, random vibration according to the vehicle profile, and impact tests. AMS helps customers plan test programs, supplies samples from manufacturers such as Henkel and Dow, and connects them with the manufacturers' labs when in-depth data is needed.
On the line, the bead weight should be measured at a fixed frequency and recorded together with the material lot number. If an anomaly is detected at final inspection, this data helps quickly isolate the affected modules without having to quarantine an entire production shift.
Contact AMS Vietnam to discuss structural adhesive solutions for your battery module project.
