The sealing quality of a weighing sensor has a great impact on its stability and service life. A welded nitrogen filled sealed weight sensor can work stably for at least ten years, but a poorly sealed sensor cannot survive for even one year under the same working conditions. This is because water can penetrate almost all polymers, causing plasticization and stress concentration, reducing strength, damaging insulation, and causing electrochemical corrosion of metals, leading to instability. After absorbing moisture, strain gauges and strain adhesives will cause the adhesive layer to expand, resulting in a decrease in bonding strength and scratch, a decrease in insulation resistance, zero drift, and some performance deterioration. So sealing and reliability are the prerequisites for the stable operation of weighing sensors. At present, there are many sealing methods, and the most practical and effective sensor technologies are:

1. The welding nitrogen sealing method uses membranes, corrugated plates, corrugated tubes, and other elastic components and outer shells to form a whole through welding, and then vacuum is applied to fill 90% nitrogen and 10% helium gas. The gas holes are sealed with conical pins or screws dipped in glue, and the bridge circuit is connected to the external circuit through replaceable alloy glass terminals sealed with tin welding. It can be said that this is the most reliable sealing method.

2. Open sealing method: suitable for weighing sensors without protective shells. The sensors used in electronic pricing scales are made of liquid isobutylene rubber or various vulcanized rubber, with surface open sealing. Shear type weighing sensors with blind holes use an open seal with two layers of different moisture-proof agents injected into the blind holes and one layer of sealed knee inside the blind holes. The outer sealant has moderate hardness and excellent adhesion to blind hole walls, and can work in environments with high humidity.

3. Open and welded sliding sealing method is a product of the combination of open sealing and welded sealing technologies, suitable for circular section cantilever beam structures sealed with corrugated tubes. The specific method is. Apply liquid isobutyric rubber or vulcanized rubber to all sealed surfaces of the elastic element (including surface mount and non surface mount areas, solder circuit boards, etc.), and seal the corrugated tube and elastic element with tin solder after curing. The sealing theory is that after welding the corrugated tube, the external air cannot exchange with the internal air, and the oxygen and moisture in the internal air have almost no effect on the moisture-proof agent. In summary, during the implementation of the above three sealing technologies, special attention should be paid to the influence of welding heat on the weighing sensor, post weld leakage methods, purification of nitrogen and helium, moisture-proof agents, and curing of sealant.