Delamination of Double-Sided Aluminum Substrates: Analysis of Industry-Wide Issues and Countermeasures

Substandard Insulating Adhesive Quality: Insulating adhesive is the core medium connecting the aluminum core and copper foil, and its bonding strength, temperature resistance, and moisture resistance directly determine the delamination risk. Using low-quality adhesives (such as insufficiently pure epoxy resin or imbalanced curing agent ratio) may achieve acceptable initial bonding effects, but the adhesive layer is prone to aging and embrittlement after long-term use or high-temperature treatment, losing bonding force and causing delamination. Meanwhile, poor compatibility between the adhesive and aluminum core/copper foil can lead to “false bonding,” where the layers appear tightly bonded but actually have insufficient bonding strength.

Inadequate Aluminum Core Surface Treatment: Oxide layers, oil stains, and impurities on the aluminum core surface seriously affect the bonding force between the adhesive layer and aluminum core. Regular manufacturers perform anodization, passivation, grinding, and other treatments on the aluminum core to form a rough surface and enhance bonding force. If manufacturers omit these steps to save costs, or the treated aluminum core surface is re-contaminated with oil stains or moisture, the adhesive layer cannot closely adhere to the aluminum core, making delamination between the aluminum core and insulation layer highly likely in the later stage.

Out-of-Control Lamination Process Parameters: Lamination is a critical link in the formation of double-sided aluminum substrates, requiring precise control of three key parameters: temperature, pressure, and time. Excessively high temperature causes over-curing and embrittlement of the adhesive layer, while excessively low temperature results in incomplete curing and insufficient bonding strength. Insufficient pressure fails to expel interlayer air bubbles, forming voids that expand when heated and trigger delamination. Both excessively long and short lamination times affect the cross-linking reaction of the adhesive layer, reducing bonding strength. In addition, double-sided aluminum substrates require symmetric lamination; uneven pressure or temperature on both sides causes stress concentration, increasing delamination risk.

Incomplete Curing Process: Post-lamination secondary curing is required to ensure complete cross-linking of the adhesive layer. Insufficient curing temperature or time leaves the adhesive layer in a “semi-cured” state, with suboptimal bonding strength and long-term residual stress. Stress release during use leads to delamination. Some small factories shorten curing time to increase production capacity, which is a common process flaw causing delamination.

Standardize Storage Conditions: Store double-sided aluminum substrates in a dry, well-ventilated environment at room temperature (20℃±5℃) with relative humidity controlled at 40%~60%. Stack no more than 5 layers of boards to avoid deformation due to pressure. Use moisture-proof packaging during storage; use opened boards as soon as possible and seal unused portions promptly to block moisture erosion and stress accumulation from the environmental perspective.

Strict Quality Inspection Upon Receipt: Conduct multi-dimensional testing quickly after receiving goods. Visually inspect the board edges for debonding, warping, and voids; gently bend the boards by hand to check for abnormal noises indicating delamination. If conditions permit, conduct sampling peel tests (using a tensile tester to measure the bonding force between copper foil and insulation layer) and thermal shock tests (-40℃~125℃ for 10 cycles) to identify defective batches in a timely manner and prevent hidden dangers from entering subsequent processes.

Strictly Control Service Life: Try to complete SMT within 3 months after PCB production, which is crucial for reducing delamination risk. However, from the perspective of actual business scenarios, this requirement is difficult for customers to fully accept, especially for small-batch, multi-batch buyers, making timeliness control challenging. Advance risk notification and communication are necessary.

Strengthen Post-Processing Protection: Handle boards with care during assembly and transportation to avoid external impact and bending, preventing interlayer microcracks. For parts susceptible to high temperatures, adopt heat dissipation optimization measures (such as adding heat dissipation holes or matching heat sinks) to reduce the aging rate of the adhesive layer and extend the service life of the boards.

Replace with High Thermal Conductivity FR4 Boards: High thermal conductivity FR4 boards have better heat dissipation performance than ordinary FR4, with strong structural stability and extremely low delamination risk. Their production and storage processes are more mature, requiring no strict timeliness control. Suitable for scenarios with moderate heat dissipation needs and high reliability requirements, they can effectively avoid delamination hidden dangers of double-sided aluminum substrates.

Replace with Double-Sided Copper Substrates: Double-sided copper substrates have superior thermal conductivity and structural stability compared to double-sided aluminum substrates, with a much lower delamination defect rate. They are suitable for high-temperature and high-frequency working conditions. Currently, a large number of automotive PCB products have switched to double-sided copper substrates, which not only meet the strict heat dissipation requirements of automotive electronics but also fundamentally solve the delamination problem, making them suitable for high-end, high-reliability scenarios.