Epoxy resin potting temperature sensor common problems:
Epoxy potting compound is a multi-component composite system: Resin, curing agent, toughening agent, fillers and other components, The viscosity, reactivity, service life, Heat, etc. need to be in the formula, process, Casting size structure and so on for a comprehensive design, So comprehensive balance. However, if improper use of epoxy resin leads to the generation of bubbles after curing, Here we analyze a NTC thermistor epoxy powder encapsulation after curing causes bubbles:
1. The purity of epoxy resin powder is not high, Containing slag quality, Dissolution time is not enough or product cleaning does not achieve a clean effect
2, stirring too fast,
3. The intensity is too fierce, wrong way.
4, ethyl acetate and other solvents add too much,
5. The temperature sensor insulation, and residual volatile liquid between the core
6. Package temperature and time did not grasp, It may take too long, or it may be too short
7. When making the temperature sensor, The gas between the insulation and the wire is discharged from the resin end to cause the generation of air bubbles
8. Insulation with the wire bonding is not tight, There is liquid or gas residue
9. Insulation and air gaps in the conductor
10. Encapsulated vibration time to grasp the length of time are not allowed
11. If the powder is the problem of poor quality lead, When the insulation layer can not withstand high temperature and melting, resulting in air bubbles.
12. When epoxy resin is mixed with air, The added curing agent contains moisture,

Yaxun electronic temperature sensor with many years of production experience, For NTC thermistor package prone to bubble phenomenon summarized the following solutions:
1. To take temperature-level curing, Two-layer package.
2. To ring-shaped tools up and down to pull-type mixing, Do not force too much
3. Filling to avoid a bubble when the place, The bubbles are preferably discharged as soon as possible
4. Dry thoroughly, If the drying is still not good bubbles, Can only explain the gap in the air out of the bubble
5. Make the temperature sensor so that the gas is not discharged from the chip side
6. Inspect the lead-side insulation and metal lines are not blocked
8. Preheat before painting to be enough heat (and immediately after preheating coating)
9. Apply a layer of lacquer to the end of the temperature-sensing lead
10. Stick the product to flux, dry and then encapsulate
11. Before pouring the temperature of the wire inside the air emptying
12. There should be no separation between sticking powder coating and preheating
13. Add defoamer and reduce the curing speed
14. Before using the product, First check to Dijiao whether the product is dry, Workshop humidity can not be higher than 60%. Because the water on the product performance is very large, Mainly bubbles, Because the excess water vapor or water and epoxy contact and epoxy resin will be combined, Form many hydrogen bonds, Is not conducive to bubble exclusion.
15 epoxy resin and curing agent after mixing three-dimensional cross-linking reaction, This reaction is a chemical reaction which is exothermic. The main and the temperature of the mixture, In the high temperature when the epoxy reactive group and the curing agent is very easy to cause reaction. So when using epoxy epoxy preheating temperature should not be too high, Generally maintained at 90 degrees or less, Mixing temperature of 40 to 50 degrees.
16. Since the epoxy resin is an exothermic reaction, In the use of the weight of each ingredient should not be too much, According to the reaction principle of epoxy, the more the amount of ingredients, the more likely to cause the reaction of the mixture to speed up.
17. Mixing time should not be too long. As the mixture itself with temperature, After mixing the epoxy resin viscosity is very low, At room temperature is easy to settle. Epoxy resin after the settlement if the product will be poured into the product to bring a great risk. Because after the settlement of the internal ratio of epoxy has been out of tune, Floating in the top of the epoxy resin and curing agent, In the curing time will have a huge shrinkage and strong internal stress. On the curing of the product may cause deformation, cracking, insulation strength decreased and a series of problems. Proposed with a good mix of room temperature storage time of not more than 1 hour, Mixing time is too long in the use of the mixture need to stir again.

The above information is for reference only, If you have questions please contact Ya Xun electronic engineering, our company will give you specific companies design Program