Control of Four Core Process Parameters
Pressure Control
The thicker the diaphragm, the higher the required pressure; the pressure shall be set as needed and must not be excessively high to prevent diaphragm damage and deformation.
Temperature Control
Heating increases the fluidity of the adhesive and assists in defoaming; excessive temperature is prohibited to avoid the generation of pinhole-like microbubbles and bubble rebound; the production adopts the synchronous operation of pressure application and heating.
Time and Pressure Boosting Control
Sufficient pressure holding ensures the full flow of the adhesive and complete defoaming; the larger the product size, the appropriately shorter the pressure holding time can be; rapid pressure boosting is strictly prohibited to prevent diaphragm wrinkling.
Pressure Relief Rate Control
The temperature shall be kept constant throughout the pressure relief process, and the pressure shall be slowly relieved in gradients to atmospheric pressure; excessive pressure relief rate will directly cause bubble rebound and recurrence.
Equipment and Process Supporting Control
Automatic vacuum laminating machine is adopted for pre-lamination to reduce primary bubbles; high-pressure defoaming machine is matched to eliminate residual microbubbles.
Lamination and defoaming must be carried out in a clean room, and strict pre-dust removal shall be done to eliminate bubbles caused by dust and impurities.
OCA Material Quality Control
Strictly control the incoming quality of OCA adhesive; inferior adhesive has many impurities and poor viscosity, which is prone to late bubble rebound after high-pressure defoaming.
The inherent impurities in OCA adhesive cannot be repaired by the process; once detected, they shall be directly scrapped and not put into the production process.
Traceability Control of Bubble Defect Causes
Air bubbles: Focus on optimizing equipment process parameters and product structure design;
Dust and impurity bubbles: Strengthen the cleanliness of the workshop and pre-lamination dust removal;
OCA inherent impurity bubbles: Strictly select incoming materials, and directly scrap defective products.
Finished Product Inspection Quality Control
At present, manual visual inspection is the main method, without the intervention of AOI (Automatic Optical Inspection) equipment; it is necessary to standardize inspection standards, improve the detection ability of operators, reduce missed inspections, and stabilize the delivery quality.
