The sintering process must meet the sintering curve to avoid the occurrence of voids in the thick film resistor paste

The common failure modes of thick film heating elements include voltage breakdown, thick film circuit burnout, electrical contact burnout, etc. Thick film circuit burnout is Mainly, but also in proportion Major failure modes. Through consultation and experimental analysis with various thick film manufacturers, the effective mechanism of thick film heating elements is roughly summarized as follows.

Voltage breakdown mainly occurs during the production cycle of thick film components, and the main reasons for voltage breakdown of thick film components are as follows:

(1) The influence of substrate material, including the metallographic structure, composition, and surface roughness of the substrate, has a significant impact on the insulation effect of the insulating medium. Among them, the metallographic structure and chemical composition affect the corrosion resistance of stainless steel, while the composition of stainless steel determines its expansion coefficient. If the expansion coefficient of the slurry is not consistent with that of the substrate, it may lead todielectric pasteCracks and even delamination occur. Surface roughness can also directly affect the adhesion effect of the medium. Choosing the appropriate roughness can improve the adhesion effect, while the cleanliness of the substrate surface can also affect the insulation performance. So strict control must be exercised over the substrate material, ensuring consistency in chemical composition, surface roughness, and surface cleanliness.

(2) 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, high precision sintering equipment is required, and on the other hand, the sintering process must meet the sintering curve to avoid the occurrence of voids and other phenomena that may affect insulation performance.

(3) The impact of production environment. The environmental temperature, humidity, and air dryness will all affect the insulation performance of the product, and the production process must control the environmental factors carefully.

(4) During the use of the product, insufficient creepage distance caused by liquid leakage or moisture adhering to the surface of the heating element can also lead to breakdown phenomenon.

Thick film circuit burnout mainly occurs during the product's usage stage, and the main reasons for this phenomenon are as follows:

(5) The thickness of the heating resistor is uneven. Both screen printing and sintering processes will affect the thickness uniformity of thick film resistors. When thick film unevenness occurs, weak links have high resistance and heat generation, which can easily form hotspots Finally burned out.

(6) Fever on the body surface with uneven temperature distribution. The routing method on the surface of thick film heating elements and the structure of the product have a significant impact on the distribution of temperature field. When the temperature field distribution is uneven, it can easily lead to different expansion coefficients of various parts of the substrate and heating wires, which can damage the circuit. What is the uniformity of temperature field when designing thick film heating elements One of the important indicators.

(7) The temperature controller does not provide timely protection. When the appliance is in a dry burning or other situation that causes abnormal temperature rise, the heating element will be protected at 100 ℃ per second or even in a timely manner It will eventually lead to damage to the heating resistor. So the choice of protector is crucial for the lifespan of thick film heating elements.

Advanced Institute of TechnologyThick film resistor pasteIn fact, it also belongs to a type of paste. Paste is an organic substance with general colloidal properties that can dissolve or expand in water, becoming a viscous and plastic paste. It can be used as a transfer agent to carry dyes and other chemicals onto fabrics. After the printing is fixed, it is finally washed away. The slurry itself does not participate in a series of chemical reactions, but only serves as a medium. The slurry should be completely uniform and free from undissolved substances such as coarse particles, yarn heads, fluff, etc., and there should be no hard sand particles or metal debris left in the slurry. Therefore, pre filtration and accelerated mixing should be carried out before printing.

Precious metal resistor pasteIt is a paste used to manufacture thick film resistors with precious metals as the conductive phase. Mainly used as thick film resistors, resistor networks, hybrid integrated circuits, and resistors and electrodes for special purposes. Some now use metals, their sulfides, and polymer organic compounds with higher chemical stability as conductive phases. Divided into silver palladium slurry, ruthenium dioxide slurry, ruthenate slurry, and iridium and rhodium slurry. Among them, ruthenium based slurries are widely used. They have good chemical stability, thermal stability, and moisture resistance, high precision and wide range of resistance values, small temperature coefficient of resistance, high resistance and low noise, and good compatibility with silver based conduction bands.
If you need this product or would like to learn more about related issues or product information, please contact us. We will solve your problems and provide services: