SMT BGA Voids Formation and Prevention-2


1.Furnace temperature curve is improperly set up before SMT

   ① In the temperature rising section, the gradient is set too high, causing the rapidly escaping gas to detach the BGA from the pad; 

   ② The duration of the heating section is not long enough. 

When the temperature rises, the gas that should be volatilized has not completely escaped. 

This part of the gas continues to escape during the reflow phase, affecting the fluxing system to play a role in the reflow phase. 

2. The solder paste solvent is not properly matched

   ① During the heating phase, the rapidly escaping gas propels up the BGA, causing misalignment and barriers; 

   ② During the reflow phase, a considerable amount of gas still escapes from the solder paste system, but is limited by the narrow space between the BGA and the BGA pad. 

These volatile gases cannot smoothly escape through this space, causing them to be squeezed. Molten solder joints and check manually. 

3. Insufficient ability of solder paste to wet the pad before pcb assembly

4. The surface tension of the solder paste system is too high during the reflow phase 

5. The solder paste system has a high non-volatile content 

6. Carrier rosin quality 

7. The amount of rosin used Another reason for the BGA cavity is the back-wetting phenomenon during the welding process. 

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