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Time of issue:2020-07-15 00:00:00
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Why do PCB boards need to be baked?

(Summary description)We know that the general baking is to evaporate the excess water by heating, and the PCB board is no exception. Dehumidification and moisture removal is the main purpose of baking. Because there are water molecules in the air, if the produced PCB board is exposed to the air for a long time, external moisture may enter the PCB board, which will cause the board to burst or delamination when the PCB is soldered.
Moreover, the materials used in many PCB circuit boards are easy to allow water molecules to condense and invade. If the content of water molecules exceeds the relevant regulations, these internal water molecules will be...

Why do PCB boards need to be baked?

(Summary description)We know that the general baking is to evaporate the excess water by heating, and the PCB board is no exception. Dehumidification and moisture removal is the main purpose of baking. Because there are water molecules in the air, if the produced PCB board is exposed to the air for a long time, external moisture may enter the PCB board, which will cause the board to burst or delamination when the PCB is soldered.
Moreover, the materials used in many PCB circuit boards are easy to allow water molecules to condense and invade. If the content of water molecules exceeds the relevant regulations, these internal water molecules will be...

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We know that the general baking is to evaporate the excess water by heating, and the PCB board is no exception. Dehumidification and moisture removal is the main purpose of baking. Because there are water molecules in the air, if the produced PCB board is exposed to the air for a long time, external moisture may enter the PCB board, which will cause the board to burst or delamination when the PCB is soldered.

Moreover, the materials used in many PCB circuit boards are easy to allow water molecules to condense and invade. If the content of water molecules exceeds the relevant regulations, these internal water molecules will be heated and atomized into water during the reflow furnace, wave soldering furnace, hot air leveling or hand welding where the instantaneous temperature reaches more than 200 degrees. Steam, the volume of water vapor will expand rapidly as the temperature rises.

When the temperature is higher, the volume of the atomization is also larger. At this time, when the water vapor cannot escape from the PCB in time, it is likely to expand the PCB, thereby reducing the vias between the layers of the PCB (via ) Pull off, causing the PCB to separate between layers. In severe cases, blistering, swelling, and plate bursting can even be seen on the outside of the PCB. There is also a problem that sometimes the PCB surface does not see bubbles, bursts, etc., but in fact the inside of the PCB has been damaged, which will affect the functional stability of electrical products over time, and ultimately lead to product failure . This is the reason why PCB boards need to be baked.

However, the PCB baking process is relatively cumbersome. For example, when baking, the packaging must be removed before it can be placed in the oven, and then a temperature of more than 100°C (the temperature is mostly set at 120+/-5°C) Come to bake to ensure that the moisture can evaporate from the PCB board. And the baking time is set according to the thickness and size of the PCB. Only after the baking is completed, the circuit board can be printed on the SMT line and soldered in the reflow furnace.

The last issue worth noting is that in order to reduce or avoid PCB bending and deformation due to stress release during the cooling period after baking, thinner or larger PCBs need to be pressed with heavy objects after baking. Because once the baked PCB is bent and deformed, there will be offset or uneven thickness when printing the solder paste on the SMT patch. This will also cause a large number of solder short circuits or voids during the subsequent reflow. Defects such as welding occurred.

The above is the reason why the PCB board needs to be baked and the baking precautions, I hope to help everyone!

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