Enhancing Semiconductor Reliability with Burn-in Boards

Semiconductor manufacturers utilize burn-in boards to assess reliability of IC under stress. The tests subject semiconductor devices, including laser and photodiodes, to extreme temperatures and voltages to detect early failures. Most burn-in boards have multiple connectors, supporting 64 to over 1000 devices concurrently., enabling HAST, LTOL, and HTOL tests. For example, these boards are constructed using materials like IS410 and polyimide, chosen for their ability to withstand  temperatures ranging from 155°C to >250°C. High-temperature-resistant connectors and test sockets  ensure that burn-in boards remain intact under prolonged stress, effectively reducing early-life faults in key applications. Each semiconductor component undergoes rigorous testing against exacting reliability criteria before release, ensuring optimal performance and longevity.

Criteria for Selection of Burn-in Board Materials

Selecting materials for burn-in boards that can withstand high temperatures and electrical stresses is crucial. The thermal conductivity of the material affects its ability to dissipate heat during testing, reducing degradation of both the board and the semiconductor devices. Additionally, material durability, especially thermal stability, is essential to prevent degradation at elevated temperatures. Moreover, the material’s electrical insulation resistance is critical in preventing short circuits and current leakage at high voltages, ensuring structural integrity and operational efficiency of the board. To choose suitable materials that meet specific application requirements, semiconductor manufacturers must carefully evaluate these factors under various test conditions, including maximum temperature and exposure time of the board.

Common Materials Used in Burn-in Boards

Burn-in boards utilize a variety of materials including FR-4, polyimide, BT epoxy, IS410, and 370HR composites. FR-4 is suitable for less severe burn-in conditions due to its ability to withstand temperatures up to 200°C. In contrast, polyimide is preferred for higher-temperature applications, boasting thermal stability and mechanical strength capable of enduring temperatures up to 250°C. Multilayer PCBs often utilize BT epoxy for its excellent insulating properties and resistance to thermal stress. IS410 is suitable for applications up to 155°C. Additionally, 370HR is specifically optimized for a glass transition temperature (Tg) of 180°C to ensure maximum reliability.

Highly Accelerated Stress Test (HAST)

The Highly Accelerated Temperature and Humidity Stress Test (HAST) is designed to intensify environmental and operational stress to speed up testing, reducing product lifetime testing duration. This advanced testing method  rapidly evaluates semiconductor device reliability under extreme conditions, effectively uncovering moisture-induced degradation and other flaws. HAST is crucial for preventing semiconductor failures in humid and high-temperature  environments, making it essential for rugged electronics like automotive and outdoor telecommunications equipment. (Read more :Preventing Electrochemical Migration in HAST)

Temperature Humidity Bias (THB)

The Temperature Humidity Bias (THB) test is essential for assessing the endurance of electronic components under combined temperature and humidity stress. This testing method reveals how materials and electronics respond to prolonged exposure to moist and hot conditions. THB specifically analyzes factors such as corrosion, electrochemical migration, and insulation degradation. For instance, it evaluates the performance of humidity-sensitive printed circuit boards and capacitors. By utilizing THB, manufacturers can enhance material selection and packaging processes, thereby improving overall product reliability and confidence. Notably, the previously mentioned HAST is an accelerated version of the THB test, and either can be selected based on the specific testing requirements.

High-Temperature Operating Life (HTOL)

The High-Temperature Operating Life (HTOL) test is a critical component of the broader Operating Life Test (OLT) suite, designed to verify the stability and durability of semiconductor devices under high-temperature conditions. HTOL specifically targets the identification of thermal aging failure mechanisms, such as semiconductor junction degradation, metallization migration, and dielectric breakdown. By closely monitoring these failure processes, manufacturers can refine device designs and accurately predict the long-term reliability and operational lifespan of semiconductor components, particularly in demanding applications like aerospace and automotive engine controllers. (Read more : How to interpret MTTF after HTOL?)

Power Temperature Cycling

The Power Temperature Cycling test is an essential procedure in semiconductor manufacturing that subjects IC to repetitive heating and cooling cycles. This test involves alternating long periods of power being on, which allows heat generated by the chip to transfer to the Cu baseplate, with periods of power being off, facilitating the cooling of the entire IC. Due to the large surface area of the Cu baseplate, significant thermal expansion occurs, making this test particularly suitable for evaluating the joints of the Cu baseplate. This process is crucial for assessing the durability and reliability of semiconductor components under fluctuating thermal conditions.