Author Topic: Some questions about a BGA solder balls defect  (Read 1561 times)

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Offline SundyTopic starter

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Some questions about a BGA solder balls defect
« on: January 13, 2025, 03:43:43 am »
Some small solder balls would appear around the solder joint during the reflow soldering process (only occur in the air atmosphere).

The whole TEST reflow process is:
a. Place solder paste onto stencil/screen and print the terminal pattern onto the test substrate by wiping paste over the stencil/screen in one smooth motion using rubber or metal squeegee.
b. Remove the stencil/screen carefully to avoid smearing the paste print.
c. Verify a paste print equivalent in geometry to the terminal of the device to be tested.
d. Place the terminals of the component being tested onto the solder paste printed pattern.
e. Verify the component placement by appropriate magnification.
f. Place the test substrate into the applicable reflow equipment and conduct the reflow process.
g. After reflow, carefully remove the substrate with the component(s) and allow to cool to room temperature.
h. Remove the component(s) from the substrate. The component leads may adhere slightly to the substrate due to the flux
residue.
i. Before examination, all leads shall have all visible flux residues removed. Care should be exercised in the flux residue removal process to not damage the leads or terminations.

Now I doubt that this problem may be caused by the wettability of the solder paste( for we change the solder paste component).
Can anyone tell me what is the reasons of this "satellite balls" phenomenon? :)
 

Offline thm_w

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Re: Some questions about a BGA solder balls defect
« Reply #1 on: January 13, 2025, 10:06:08 pm »
What is the "reflow equipment"?

If its hot air based then it can blow stuff around. Or if its not properly leveled, or the rack is uneven, etc.
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Offline SundyTopic starter

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Re: Some questions about a BGA solder balls defect
« Reply #2 on: January 14, 2025, 01:45:40 am »
I don't know whether it is.
Reflow oven : ERSA HOTFLOW 320.
 

Offline Harshit Shah

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Re: Some questions about a BGA solder balls defect
« Reply #3 on: February 01, 2025, 09:54:34 am »
Hey..! Sounds like a tricky BGA issue! A few things to check—have you looked at your reflow profile? Sometimes improper heating can cause solder ball defects, especially if there's warping or oxidation. Also, stencil design and paste volume can play a big role. If the issue is recurring, an X-ray inspection might give a better picture of what's happening under the package. Let us know what you've tested so far! 👌
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Offline NorthGuy

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Re: Some questions about a BGA solder balls defect
« Reply #4 on: February 01, 2025, 02:52:51 pm »
I don't think soldering without copper models the real soldering process adequately. Copper attracts solder and keeps it in place.
 


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