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Relationship between the success rate of BGA welding and welding quality

Relationship between the success rate of BGA welding and welding quality


At present, the BGA welding is mainly referred to the success rate, in fact, the success rate is not true

reaction welding. We believe that a simple emphasis on the success rate of a certain deceptive, welding

success rate will be false, which includes at least 5 cases:


1.Not welded. There are quite a part of weld motherboard can not through the welding will eliminate

the fault, for example, in the constant temperature box baking a few hours, a part of weld failure can

be ruled out. A similar situation is also found in the rework station, through high temperature heating

even without solder melting (of course, not welding), exclude a part of the fault.


2.Part of the ball it is heated to the critical state. When the solder is in critical condition, the color is black,

when it is set, it can only be attached to the solder joint, and once the force will be separated from the

solder joint.


3.Uneven chip welding. If the motherboard welding deformation, or solder melting is not uniform, it may

appear this kind of circumstance. See from the chip edge edge chip is not parallel with the main board,

solder ball, solder fill part of flattened elongated part.


4.PCB plate aging damage.


5.Although the solder melting and welding uniform, but not real.


Appear above several situation, although the fault may temporarily excluded, but common features is after

repair of the motherboard with long, may soon repair back. All the above circumstances related to

rework station and method of operation.


We design and develop reworkstation welding scheme is the starting point of the welding quality, welding

or firmness. The success rate is high and can not guarantee the high welding quality, but if the welding

quality is high, it can guarantee a high success rate. We think we should rule out the above situation, to

do the following:


1.Welding process must be smooth, no effort. If the solder melting is very difficult, we can not guarantee the

quality of welding. The rework station and welding operation scheme have a relationship.


2.Reworkstation welding BGA components is heating with a heating, heating, to meet the good. This includes

the upper heating curve, the lower part of the preheating temperature, the amount of preheating, etc.


3.All motherboards heating process may appear deformation, rework station and heating schemes suitable

can reduce the deformation and remaining part rely on a fixed board to resolve. Motherboard fixed good,

can eliminate or reduce the impact of the main board of the deformation of the welding, so the fixed board

should be careful, serious.


4.Must pay attention to the operation method and some detail processing. In order to avoid these cases,

check the solder ball is melting and melting solder ball handling is essential, in any rework station fool type

welding to ensure the welding quality can not be.



TAG:  BGA welding PCB plate solder lead solder
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