Highly Accelerated Stress Test (HAST) and Its Application in BGA100 Chips

Highly Accelerated Stress Test (HAST) is a method used to evaluate the reliability of electronic components under high temperature and high humidity conditions. This article will take the BGA100 chip as an example to detail the standards, testing purposes, and the design of burn-in boards and BGA100 burn-in sockets.

HAST Testing Standards

HAST testing typically follows international standards such as JEDEC JESD22-A110 and IEC 60068-2-66. These standards specify the specific conditions for testing, including temperature, humidity, and testing duration. Typical HAST testing conditions are as follows:

• Temperature: 110°C to 130°C
• Humidity: 85% to 100% relative humidity
• Pressure: 2 atmospheres (approximately 202.6 kPa)
• Testing Time: 48 to 96 hours

These conditions are designed to accelerate the aging process of components, allowing for the evaluation of their long-term reliability in a shorter time.

Additionally, different types of PCB materials may have specific conditions in HAST testing. Here are some common HAST testing conditions:

1. JPCA-ET-08: 110°C, 120°C, 130°C / 85% R.H. / 5～100V
2. High Tg Epoxy Multilayer Boards: 120°C / 85% R.H. / 100V, 800 hours
3. Low Dielectric Constant Multilayer Boards: 110°C / 85% R.H. / 50V, 300 hours
4. Multilayer PCB Wiring Materials: 120°C / 85% R.H. / 100V, 800 hours
5. Low Expansion Coefficient & Low Surface Roughness Halogen-Free Insulation Materials: 130°C / 85% R.H. / 12V, 240 hours
6. Optically Active Cover Film: 130°C / 85% R.H. / 6V, 100 hours
7. COF Film Thermosetting Boards: 120°C / 85% R.H. / 100V, 100 hours

Purpose of HAST Testing

The main purpose of HAST testing is to evaluate the reliability of electronic components in actual use by simulating extreme environmental conditions. Specifically, HAST testing can help identify the following issues:

1. Material Defects: Detect the stability of chip packaging materials under high temperature and high humidity conditions.
2. Manufacturing Defects: Identify potential defects in the manufacturing process, such as poor soldering and unsealed packaging.
3. Design Defects: Evaluate the performance of chip designs under extreme conditions to ensure their reliability in actual applications.

Design of the BGA100 Chip Burn-in Board

BGA100 (Ball Grid Array 100) is a common chip packaging form with 100 solder balls. To conduct HAST testing, a specially designed burn-in board is needed to accommodate the BGA100 chip.

Design Requirements for the Burn-in Board

1. Material Selection: The burn-in board typically uses high-temperature resistant materials such as high-performance FR-4, polyimide, or ceramic substrates to ensure stability under high-temperature conditions.
2. Circuit Design: The burn-in board needs to have appropriate circuit designs to conduct electrical testing on the BGA100 chip. The circuit design should ensure reliable connections between all solder balls and the pads on the burn-in board.
3. Thermal Management: Since HAST testing is conducted under high-temperature conditions, the design of the burn-in board should also consider thermal management to prevent damage from overheating.

Design of the BGA100 Burn-in Socket

The burn-in socket is a critical component used to mount and secure the BGA100 chip on the burn-in board. The design of the burn-in socket needs to meet the following requirements:

1. Precise Alignment: The burn-in socket should precisely align the solder balls of the BGA100 chip with the pads on the burn-in board to ensure good electrical connections.
2. High-Temperature Resistance: The material of the burn-in socket should be resistant to high temperatures, typically using high-temperature resistant plastics or metals.
3. Reliable Contact: The contact pins inside the burn-in socket should have good elasticity and conductivity to maintain stable electrical connections under high temperature and high humidity conditions.
4. Ease of Operation: The design of the burn-in socket should facilitate the installation and removal of the chip, reducing the risk of damage during operation.

Conclusion

HAST testing is an important method for evaluating the reliability of electronic components. By accelerating the aging process under high temperature and high humidity conditions, it can quickly identify potential issues in materials, manufacturing, and design. Using the BGA100 chip as an example, the design of burn-in boards and sockets plays a crucial role in HAST testing. The burn-in board should have high thermal resistance and good circuit design, while the burn-in socket should ensure precise alignment and reliable contact. Through reasonable design and rigorous testing, the reliability of BGA100 chips can be effectively improved, ensuring stable performance in actual applications.