Key Considerations for Pre-Mounting Chip Baking

2025-06-16

In electronics manufacturing, chip mounting refers to the process step of installing chips onto printed circuit boards (PCBs). The quality of chip mounting directly affects the performance and reliability of electronic products. Pre-mounting baking is a crucial step to ensure mounting quality and chip reliability.

During manufacturing, transportation, and storage, chips readily absorb moisture from the environment. If not removed, this moisture rapidly vaporizes and expands during high-temperature soldering, generating significant stress. This can lead to package cracking, solder joint failure, or internal circuit damage, severely compromising product quality and reliability. Baking aims to remove internal moisture and surface contaminants from the chip, reduce internal stress, improve solderability and reliability, and ensure mounting quality.

I. Functions of Pre-Mounting Chip Baking

Moisture Removal:Chips absorb ambient moisture during storage and transportation. During high-temperature soldering, vaporizing moisture causes rapid internal stress build-up, potentially leading to package cracks, solder joint failures, or internal circuit damage. Baking gradually evaporates internal moisture, reducing this risk during soldering.
Enhanced Solderability: During baking, surface oxides and contaminants are reduced along with moisture evaporation. This improves the solderability of chip leads/pads, allowing solder to bond more effectively and enhancing welding quality and reliability.
Stabilized Chip Performance:Moisture presence can affect electrical performance and long-term stability. Removing moisture through baking results in more stable performance during operation and extends service life, significantly improving the overall quality and longevity of electronic products.

II. Application Fields of BCB Materials

Chip Moisture Sensitivity Level (MSL): Chips have different MSL ratings, dictating specific baking temperature and duration requirements. Higher MSL levels demand stricter baking protocols. For instance, MSL1 chips are generally insensitive to humidity and require no baking, whereas MSL4 chips typically require baking if not mounted within 72 hours after package opening.
Control Baking Temperature and Duration: Temperature and time depend on chip material, package type, and MSL. Temperatures typically range between 90°C and 125°C. Cumulative baking time should not exceed 96 hours or the supplier's specified maximum. For example, BGA components are usually baked at 125°C ±5°C for no longer than 24 hours.
Verify Packaging Material Temperature Tolerance: Packaging materials (trays, tubes, tape-and-reel) can release gases during baking, potentially affecting component solderability. Ensure packaging can withstand baking temperatures. Standard trays can typically bake at 125°C, but materials like low-temperature trays, tubes, or tape may require baking temperatures below 60°C.
Prevent Chip Oxidation:High-temperature baking may cause terminal oxidation or intermetallic compound growth, leading to solder defects like cold joints. Strictly limit baking temperature and duration. After baking, proceed with mounting promptly to prevent re-absorption of moisture or oxidation due to prolonged air exposure.

III. Application Scope of Pre-Mounting Chip Baking

●SMT Assembly: In SMT production lines, almost all chips requiring mounting undergo baking before placement and soldering. This ensures chip dryness and solderability, preventing moisture-related soldering defects and product quality issues.

●Chip Manufacturing: Baking is also performed during chip manufacturing processes, such as wafer fabrication and packaging/testing, to prevent moisture from affecting performance in subsequent processing or end-use.

●Electronics Manufacturing: Baking is essential for chips used in high-reliability electronics like aerospace, automotive, and medical devices, ensuring stable operation under harsh environmental conditions.

IV. Suitable Baking Ovens

●Convection Ovens: Utilize a fan system for uniform hot air circulation, ensuring even chip heating and improved baking quality. Their large capacity allows simultaneous baking of many chips, making them suitable for mass production. Careful selection of airflow mode is necessary to avoid localized overheating or temperature inconsistencies.

●Vacuum ovens: Bake chips under vacuum conditions. This lowers the boiling point of moisture, facilitating easier removal from the chip interior and increasing baking efficiency. The vacuum environment also prevents oxidation during baking, making these ovens particularly suitable for high-MSL chips and applications with strict oxidation requirements.

Pre-mounting chip baking is a critical step for ensuring electronic product quality and reliability. By properly controlling temperature, duration, and conditions, internal moisture is effectively removed, solderability is enhanced, and production risks are reduced. In practice, select appropriate ovens and baking processes based on chip characteristics and specifications, strictly adhering to baking precautions to guarantee chip mounting quality and final product performance.