The common failure modes of thick-film heating elements mainly include breakdown voltage, burn-out of thick-film circuits, burn-out of electrical connection contacts, etc., and burn-out of thick-film circuits is the main failure mode and also has a large proportion. By consulting with the manufacturer of the flat-panel thick-film heater, the effective mechanism of the thick-film heating element is roughly summarized as follows.

Voltage breakdown mainly occurs in the production cycle of thick film components. The main reasons for the breakdown of thick film components are as follows:

The influence of sintering process and sintering equipment. Each slurry has a specific sintering curve, and the sintering temperature and time are usually determined by the properties of the slurry. On the one hand, the sintering equipment is required to have high precision, and on the other hand, the sintering process must meet the sintering curve, otherwise there will be voids and other phenomena, which will affect the insulation performance.

impact on the production environment. Ambient temperature, humidity, and air dryness will affect the insulation performance of the product, and the production process must control environmental factors.

During the use of the product, insufficient creepage distance due to liquid leakage or moisture attached to the surface of the heating element will also lead to breakdown.

Thick film circuit burnout mainly occurs in the use stage of the product. The main reasons for this phenomenon are as follows:

The thickness of the heating resistor is uneven. Both the screen printing and sintering process will affect the thickness uniformity of the thick film resistor. When the thickness of the film is uneven, the weak link resistance is large, and the heat generation is also large, which is easy to form hot spots and eventually burn out.

The body surface is heated and the temperature field distribution is uneven. Usually, the wiring method on the surface of the thick monkey heating body, the structure of the product has a great influence on the distribution of the temperature field when the temperature field distribution is uneven

At this time, it is easy to cause the different expansion coefficients of various parts of the substrate and the heating wire to damage the circuit. The uniformity of the temperature field is one of the most important indicators when designing a thick waist heating element.

The temperature controller protection is not timely. When the appliance is in dry burning or other conditions that cause the temperature to rise abnormally, the heating element will be protected at 100°C per second or even in time, which will eventually lead to damage to the heating resistor. Therefore, the choice of the protector is very important for the life of the thick film heating element.

Power density or current density is high. Usually, the power or current density of the thick mold heating element must have enough margin, and the margin is insufficient, which will lead to the failure of the thick resistor under time accumulation or other abnormal conditions.

Substrate deformation. If the substrate material or structure design is unreasonable, or the substrate is deformed due to other structural reasons, the heating resistor attached to it will also undergo phase change and be damaged.

Due to the large working current of the thick film heating element, the electrical contact point is also a weak part of the heating element. Under the influence of the alternating cold and heat of the working environment of the heating element, the humid environment and other factors, it is easy to cause the contacts to oxidize and heat up and burn. Usually, the thickness and area of the thick-film conductor material should be designed with allowance, and the thickness of the contact and the silver content It is necessary to meet the actual use requirements, and the contact and the thick film conductor are combined with the elastic material by elastic connection. Generally, beryllium bronze is better, because beryllium bronze has good elasticity and electrical properties.