Why Thermal Potting Compounds Do Not Cure?

Why Thermal Potting Compounds Do Not Cure?

The main function of thermal potting compound (also known as “ab glue”) is to strengthen the overall performance of electronic components, improve practicability, enhance resistance to external shocks, and achieve the purpose of safe use and enhanced service life. thermal potting compound is a liquid glue with fluidity. After normal curing, it isolates dust, moisture, moisture, etc., can withstand changes in high and low temperature, and protect components to work stably. Once it cannot be cured normally, it must be solved immediately.

The non-curing of silicone encapsulant is divided into internal and external causes. Once this type of adhesive does not cure, it will not be able to effectively play the role of waterproof, moisture-proof and insulation in electronic products.

The internal cause of the non-curing of the potting compound

The bond strength of solvent-based adhesives is affected by the amount of residual solvent in the adhesive layer. When the amount of solvent is large, although the wettability is good, the cohesive strength of the adhesive decreases because the cohesive force of the adhesive decreases. When the affinity between the adhesive polymers is large, the adhesive strength increases with the volatilization of the solvent. When there is no affinity between the two, the adhesiveness of the adhesive is relatively large when some solvent is left, and the strength decreases with the volatilization of the solvent.

The external cause of the encapsulant not curing

  1. When the two-component potting compound is proportioned, the electronic scale is not accurate enough, resulting in the incorrect content of AB agent. When the A agent is too much and the B agent content is small, it cannot be cured normally.
  2. There is no stirring before use, or there is no layering of pigments and fillers during storage, resulting in curing failure.
  3. The curing time is not long enough, and the next step is carried out in a hurry.
  4. After opening, the airtightness is not good, resulting in moisture absorption and crystallization.
  5. Changes in ambient temperature lead to changes in the curing speed and fluidity of the adhesive; if the curing temperature is too low, the adhesive cannot be cured for a long time. Especially in winter, the temperature is lower and the curing time needs to be extended.
  6. Apparent curing failure affected by the treatment of bubbles on the surface of the cured product.
  7. Light-colored cured products will change in color due to the influence of curing temperature, ultraviolet light and other conditions.
  8. Various changes in the effect of curing temperature changes on the curing properties of materials.
  9. The operators of the adhesive potting glue may not design accelerated destructive aging life experiments according to the characteristics of the glue and the needs of electrical products.
  10. The adhesive has expired. After the expiration date, it may undergo qualitative changes and cannot be used normally. Check the expiration date before using and don’t use expired products.

How to solve the problem of not curing?

  1. Regularly calibrate the electronic scale, accurately weigh the AB agent, and stir evenly.
  2. After winter, the adhesive can be preheated or cured by heating.
  3. Arrange the adhesive according to the length of the shelf life, and use up the products that are about to expire to avoid waste.
  4. Keep the working environment safe and keep away from products that will react with silicone potting compounds.
  5. Store in accordance with the instructions in the manual and maintain good ventilation conditions.

In addition, every time the silicone potting compound is used, the material should be stirred evenly. Curing is a step-by-step process that will only become stronger until the surface and interior are fully cured.

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