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1.Wiping off residual soldering tin on the bottom bonding pad and cleaning it. Use the soldering
iron to clean up residual soldering iron on PCB bonding pad, and we can use the desoldering
woven belt and solder tip with flat spade type to clean, pay attention to not damage the bonding
pad and soldering-resistance layer when operating.
Use the dedicated cleaning agent to clean up flux residue.
2.Paint the scaling powder on the BGA bottom bonding pad. In general condition, use the scaling
powder with high viscosity, it’s helpful to splice and solder, we should sure that the shape appeared
on the bonding pad after painting the scaling powder is distinct. Sometimes we also can use soldering
paste, but the metal components of soldering paste should match with the metal components of solder ball.
Using the BGA dedicated small template when painting, the thickness of template and the opening size should
depend on the sphere diameter and ball pitch, we must examine the quality after painting, if it’s below standard,
we must clean up then paint again.
3.Choose the solder ball We should take the material of solder ball and the size of sphere diameter into consideration.
At present, the material of PBGA solder ball is 63Sn/37Pb generally, it’s same with the material used for reflow soldering,
so we must choose the solder ball whose material is same with the BGA component solder ball.
Choosing the size of solder ball is also very important, if we use the scaling powder with high viscosity,
we should choose the solder ball whose diameter is same with the BGA component solder ball; if we use
the solder paste, we should choose the solder ball whose diameter is small than the BGA component solder ball.
A)reballing device method.
If you have the reballing device, choose a piece of template match with BGA bonding pad, the opening size
of template should be larger than solder ball diameter in 0.05—0.1mm, scatter the solder ball on the template
equably, and shaking the reballing device, then the superfluous will roll in catch tank from template. Put the
reballing device on the working table, attach the BGA component been painted scaling powder or solder paste
on the nozzle, then move the nozzle down, until the BGA component close to solder ball ,then attach the
BGA component, with the help of viscosity of scaling powder or solder paste, stick solder ball on the bonding pad.
Clamp the outer border of BGA component by tweezers, turn off the vacuum pump, put the BGA component on
the working table, check if somewhere lack of solder ball, or you should supply by tweezers.
B)use template method.
Put the BGA component been painted scaling powder or solder paste on the working table. Prepare a piece of
template match with BGA bonding pad, the opening size of template should be larger than solder ball
diameter in 0.05—0.0mm, support all around the template by heel block, then put it on the BGA component,
make the distance between template and BGA is equal or less than the diameter of solder ball, and align under
the microscope. Scatter the solder ball on the template evenly, and take the superfluous down by tweezers.
Moving away template, check and supply it.
C)manual placement. Put the BGA component been painted scaling powder or solder paste on the working table,
put solder ball away one by one by tweezers or attaching-pen.
D)paint appropriate solder paste method When process the template, thicken the template thickness,
and enlarger the opening size of the template slightly, then paint the solder paste on the BGA bonding pad directly.
Due to the surface tension, come into being solder ball after reflow soldering.
5.reflow soldering With reflow soldering process, solder ball are fixed on the BGA component.
6.after soldering After finishing reballing, we should clean up the BGA component, then mount and weld as
soon as possible, prevent solder ball oxidation and components damp.