Why Should PCB Boards Be Baked?
In the semiconductor field, PCB (Printed Circuit Board) is the core component of electronic devices, widely used in smartphones, computers, automotive electronics, industrial automation equipment, communication base stations, and even aerospace equipment. It provides physical support and electrical connections for chips, resistors, capacitors, and other components. During production, storage, and transportation, PCB boards are prone to absorbing moisture from the environment. During subsequent high-temperature reflow soldering, this moisture can rapidly vaporize and expand, leading to interlayer delamination, blistering, or cracking of the PCB board, which affects product performance and reliability. Baking is a critical process to ensure the quality and reliability of PCB boards.
Functions of PCB Board Baking
1.Moisture Removal: The materials of PCB boards are hygroscopic to some extent, especially the resin substrates and fiberglass cloth in multi-layer boards, which have natural microporous structures that easily absorb moisture. During processes like high-temperature reflow soldering, the absorbed moisture rapidly vaporizes and expands, generating significant steam pressure that can cause interlayer delamination, blistering, or cracking. Baking thoroughly removes moisture from the PCB board, preventing damage to the material caused by moisture during high-temperature soldering.
2.Internal Stress Relief: During the manufacturing process of PCB boards, internal stress is generated due to various process operations. Baking subjects the board to heat treatment at a certain temperature, allowing internal stress to be released. This helps stabilize the dimensions of the board and reduces deformation caused by internal stress during subsequent processing or use.
3.Improved Soldering Performance: Moisture can oxidize the soldering surface, affecting the wettability of solder and leading to weak or faulty solder joints. After baking, moisture in the solder pads is dried out, effectively improving soldering stability and reliability and minimizing soldering defects such as weak joints.
4.Prevention of Ionic Contamination:If moisture in the PCB board is not removed, it may cause ionic contamination after high-temperature processing, increasing the risk of electrochemical migration around solder joints and leading to short circuits or reduced product lifespan. Baking reduces the likelihood of such ionic contamination, enhancing the electrical performance and service life of the product.
Baking Equipment for PCB Boards
1.Hot Air Circulation Oven: This equipment uses a hot air circulation system to ensure uniform temperature distribution inside the chamber. It features fast heating, low energy consumption, and high temperature control precision. Typically equipped with multiple temperature sensors and an intelligent control system, it can accurately control baking temperature and time according to different PCB board materials and process requirements. Suitable for large-scale production environments, it efficiently removes moisture from PCB boards.
2.Vacuum oven:By reducing internal pressure, this oven accelerates moisture evaporation and lowers the boiling point of water, allowing PCB boards to be baked at lower temperatures and avoiding thermal damage from high temperatures. With a compact internal structure, an efficient vacuum pump, and a sealing system, it ensures stable and uniform vacuum levels. Particularly suitable for baking PCB boards with high hygroscopicity, it is commonly used in the manufacturing of high-precision, high-reliability electronic products, such as in aerospace and medical electronics.
3.Nitrogen Oven:Baking is performed in a nitrogen environment, where nitrogen acts as an inert gas to isolate oxygen in the air, preventing oxidation of the PCB board during high-temperature baking. Equipped with a nitrogen supply system and gas flow control device, it can precisely control nitrogen concentration and flow inside the chamber. Primarily used for PCB boards and components sensitive to oxidation, it is widely applied in semiconductor manufacturing and the production of high-end electronic equipment to ensure high performance and reliability.
4.Tunnel oven:This is a continuous baking equipment that uses a conveyor belt to feed PCB boards into the chamber. The boards pass through multiple temperature zones for step-by-step heating, insulation, and cooling. It offers high production efficiency and automation, enabling continuous, uninterrupted production. With multi-zone temperature control, it allows flexible setting of temperature and time parameters for each zone, ensuring temperature uniformity and stability. Suitable for large-scale, high-efficiency PCB production.
Baking PCB boards is a crucial process for ensuring the quality and reliability of electronic products. It effectively removes moisture from PCB boards, prevents various issues during soldering, and improves soldering quality and reliability. Baking also prevents PCB delamination and oxidation, enhances production efficiency, and ensures the long-term stable operation of electronic products.