During the semiconductor packaging process, bubbles (also known as voids in the industry) are common defects that affect product yield and reliability. Many engineers ask: Can high-pressure defoamers really remove bubbles from semiconductor packaging? The answer is affirmative. The high-pressure defoamer, through the combination of pressure, vacuum, and temperature, can effectively eliminate small bubbles in the packaging adhesive layer and bonding interface, and is a widely used process equipment in semiconductor packaging production lines.
Where do bubbles in semiconductor packaging come from
To determine the effectiveness of a high-pressure defoamer, it is necessary to first understand how bubbles are generated. In the semiconductor packaging process, bubbles mainly come from the following aspects:
Underfill relies on capillary action to fill the fine gaps between the chip and the substrate, which can easily trap air and form sealed bubbles;
During the process of dispensing, stirring, and conveying, gases are mixed into the solidified silver adhesive and potting adhesive, which remain in the adhesive layer after curing;
In the process of film sticking and bonding, air is drawn between the film material and the substrate, forming surface or interface bubbles;
Some adhesive materials will release gas during the high-temperature curing process, leaving voids inside the thick adhesive layer.
Once these bubbles remain, they will block the heat dissipation path, become stress concentration points, cause delamination and cracking under cold and hot cycles, and also affect electrical performance. Therefore, the defoaming process is essential in the packaging production line.
Working principle of high-pressure defoamer for removing bubbles
The working principle of a high-pressure defoamer can be summarized as three stages: vacuum expansion, high-pressure compression, and temperature controlled leveling. Only by combining these three stages can tiny bubbles be completely removed
Vacuum pretreatment: First, the chamber is evacuated to a low vacuum, and the tiny bubbles inside the material expand and gather due to the pressure difference between the inside and outside. The previously imperceptible fine bubbles are "magnified" to create conditions for subsequent processing;
High pressure compression: Injecting pressure medium into a sealed chamber, according to Boyle's law (gas pressure is inversely proportional to volume at constant temperature), the volume of bubbles is greatly compressed, eventually bursting and being absorbed by the adhesive layer or dissolved in the material;
Temperature control and pressure relief: Increasing the temperature appropriately can reduce the viscosity of the adhesive material, making it easier for bubbles to escape; After the pressure is maintained, slowly release the pressure to avoid sudden pressure changes that may cause dissolved gases to re precipitate and form secondary bubbles.
Simply put, a high-pressure defoamer does not simply "crush" the bubbles, but uses vacuum to extract the bubbles, high-pressure to crush them, and temperature control to remove them completely. All three steps are indispensable.
Typical application of high-pressure defoamer in semiconductor packaging
Underfill is used to remove bubbles and eliminate voids in the narrow gaps between the chip and the substrate;
IGBT power module encapsulation, solid-state silver bonding layer defoaming, ensuring heat dissipation and insulation reliability;
Wafer protective film bonding and chip film defoaming to avoid air entrapment during the film application process;
The PCB module is fully encapsulated and defoamed to eliminate hidden voids inside the deep cavity.
In these processes, the high-pressure defoamer is usually arranged as an independent defoaming process after dispensing, bonding or sealing, and before curing, and is used in conjunction with subsequent curing processes.
How to choose a suitable high-pressure defoamer
The defoaming effect of high-pressure defoamers largely depends on whether the equipment performance and process parameters match. When selecting, you can focus on several aspects:
Whether the pressure range covers the process requirements: Different packaging processes require different pressures, and the equipment's pressure range should be able to cover the actual process;
Material and safety level of the chamber: Tanks that can withstand high pressure for a long time should be made of stainless steel and meet the corresponding safety standards for pressure vessels;
Pressure control and display accuracy: digital pressure display, switchable pressure units, convenient for on-site process personnel to set and monitor;
Manufacturer experience: Priority should be given to selecting defoamer manufacturers with long-term accumulation in the semiconductor equipment field, as process support and after-sales service are more guaranteed.
Taking the high-pressure defoamer of Baode (Shenzhen Baode Automation Precision Equipment Co., Ltd.) as an example, its tank size is ￠ 1000mm × 1200mm, made of SUS304 stainless steel material, and has a safety level of Class 2 pressure vessel standard; Use pressure of 0.1~0.7Mpa, test pressure of 1Mpa; The pressure display is digital, with units that can be switched between Mpa, kgf/cm2, bar, and psi, making it convenient for production lines with different process habits.
Conclusion
High pressure defoamers can indeed remove bubbles from semiconductor packaging, but the prerequisite is reliable equipment performance and appropriate matching of process parameters. Baode was founded in 2007 and has been rated as a national high-tech enterprise for four consecutive years. It has nearly 100 patented technologies and has accumulated over 17 years of experience in the field of semiconductor production equipment. Its high-voltage defoamer is widely used in semiconductor packaging, display bonding and other processes. If you are looking for a solution to the bubble problem in the packaging production line, you can further understand Baode's high-pressure defoamer products and select the appropriate one based on your own process requirements.
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