Application practice of preventing thermal stress cracking in surface welding with gold paste welding

In the field of modern electronic manufacturing, surface solder paste is a key material for achieving high-quality connections. Advanced Institute (Shenzhen) Technology Co., Ltd Research Platinum Brand YB8108 Surface Welding Gold PasteWidely used due to its excellent performance. However, cracking caused by thermal stress is always a major challenge in the welding process, and solving this problem is crucial to ensure product reliability and performance.

YB8108 surface welding gold paste mainly includes gold powder, organic carrier, and additives. The particle size and shape of gold powder affect its fusion effect during welding. Its average particle size is about 1-3 microns and it is spherical, which is conducive to uniform heating and fusion. Organic carriers gradually evaporate during welding. If the evaporation rate does not match the heating process, it can easily cause uneven internal structure and trigger thermal stress. For example, if the organic carrier evaporates rapidly at high temperatures, weak links may appear in the bonding between the gold powders, which can easily crack during thermal expansion and contraction.

The matching degree of thermal expansion coefficient between the gold paste and the welded substrate is crucial. YB8108 is designed to be compatible with multiple substrates. When welding ceramic substrates, if the thermal expansion coefficient deviation of the gold paste is too large, during the heating and cooling cycle, due to the large difference in expansion and contraction between the two, significant thermal stress will be generated inside and at the interface of the gold paste, leading to cracking. By adding specific fillers or adjusting the formula, the thermal expansion coefficient of the gold paste can be optimized to reduce stress generation.

The heating rate has a significant impact on thermal stress. Excessive heating causes a rapid increase in temperature difference between the gold paste and the substrate, resulting in a large temperature gradient. regarding YB8108 gold pasteIt is advisable to control the heating rate at 3-8 ℃/s. By using intelligent temperature control equipment, the gold paste and substrate are slowly heated during the low temperature stage to evenly heat up and reduce stress concentration caused by local overheating. For example, if the temperature is below 200 ℃, the heating rate is around 3 ℃/s, and then it can be accelerated appropriately, but not exceeding 8 ℃/s.

YB8108 has a specific welding temperature range, generally between 800-920 ℃, which is more suitable, with a welding time of 8-25 seconds. If the temperature is too high or the time is too long, the gold paste will sinter excessively, and the structure will become brittle; If the temperature is too low or the time is too short, the welding will not be firm. In practical operation, fine tune according to the substrate material and the thickness of the gold paste coating. When the metal substrate and gold paste are thick, the temperature can be biased towards 900 ℃ for 15-25 seconds; When the ceramic substrate and gold paste are thin, the temperature is 800-850 ℃ and the time is 8-15 seconds.

The cooling process is crucial for generating thermal stress. Rapid cooling, such as air cooling or water cooling, can cause rapid shrinkage of the gold paste and substrate, resulting in significant stress. YB8108 gold pasteNatural cooling or slow gradient cooling should be used. Natural cooling allows heat to dissipate naturally, which is time-consuming but requires less stress. Slow gradient cooling can set a cooling program, such as reducing the welding temperature to 400 ℃ at a rate of 1-2 ℃/s, and then slowly lowering it to room temperature, effectively reducing thermal stress.

The surface quality of the substrate affects the welding effect and thermal stress. Firstly, the surface needs to be cleaned to remove impurities such as oil stains and oxides. A combination of chemical cleaning and ultrasonic cleaning can be used. Secondly, surface roughening treatment should be carried out, such as sanding with sandpaper or chemical etching, to increase the mechanical interlocking between the gold paste and the substrate and disperse thermal stress. For example, after sanding ceramic substrates with 800-1000 grit sandpaper, the probability of thermal stress cracking during welding is significantly reduced.

Uniform gold paste coating can reduce thermal stress. When using high-precision coating equipment, such as screen printing, select the appropriate mesh size and adjust the scraper pressure to ensure uniform thickness of the gold paste without bubbles or pinholes. Uniform thickness can ensure consistent heating and cooling of all parts, avoiding local stress concentration. general YB8108 gold pasteIt is advisable to control the coating thickness between 10-30 microns.

Annealing treatment after welding can eliminate residual stress. For YB8108 gold paste welded parts, anneal at 550-650 ℃ for 20-40 minutes. During the annealing process, the atoms inside the gold paste are rearranged, releasing stress and improving the microstructure. By using a precise temperature controlled annealing furnace and annealing according to the set process, the cracking resistance of welded joints can be significantly improved.

When using the research platinum brand YB8108 surface welding gold paste for welding, by deeply understanding the characteristics of the gold paste, carefully optimizing the welding process, and implementing effective auxiliary preventive measures, cracking problems caused by thermal stress can be effectively avoided. This not only improves the welding quality and reliability, but also lays a solid foundation for the application of YB8108 gold paste by Advanced Institute (Shenzhen) Technology Co., Ltd. in a wider range of electronic manufacturing fields, promoting the development and progress of welding technology in the industry.
The above data is for reference only, and specific performance may vary due to production processes and product specifications.