Solder ball ocular inspection

[linux-dude]

Hi,

I had a look at the solder balls under an fpga and wonder if the joints are likely to be good? It's lead-free process.



Any thoughts are most welcome!

Regards,
Mike

 

[niciki]

Please add picture in high resolution and higher quality.

 

[linux-dude]

Please add picture in high resolution and higher quality.

I have currently no higher resolution cam available. Is it not possible to judge at this low resolution?

 

[SLK001]

The ones that are able to be seen look good enough - there is wetting on both sides of the joint. The standard test for determining what you want is called a "red dye" test. Red dye is flooded under the part and left to dry, then a one pound or so weight is mechanically attached to the top of the device (via string). The board is secured in a holder with a pulley system over the top, then the weight is suspended off to the side. Over time, the part is slowly pulled off the board, leaving red dye in areas where solder should be. This is the only test I know of to verify solder joint viability.

The red dye test is considered a destructive test, although sometimes the part comes cleanly off the board.

 

[BradtheRad]

A magnifying glass can allow a camera to get close to the work, so you can capture sharper detail. You may need to find a way to cooperate with the auto-focus (or else turn it off). Try a few test shots, to find the right distance to place the magnifier, where the camera is best able to focus on the subject, while taking in an adequate field of view.

 

[marce]

Take a set of pics. at different focusing points so we can examine the complete joint.
Never heard of the red dye test, used x-ray and optical as destroying a board makes it useless and will only tell us how that one board soldered.

 

[linux-dude]

Thanks for all responses!

I've ordered a better cam, expect delivery this week. Will post better images.

Again, thanks to all you wonderful people who spend time helping out!

Regards,
Mike

 

[SLK001]

Take a set of pics. at different focusing points so we can examine the complete joint.
Never heard of the red dye test, used x-ray and optical as destroying a board makes it useless and will only tell us how that one board soldered.

The red dye test tests your processes. If there are no failures, then your processes are in line with your production goals. It is when your failures exceed a stated goal do you need to test your processes. X-ray is generally useless in determining solder joints under a BGA, as is optical, for any pad more than 3 -4 rows in. Quality should be designed in, not tested in - this is where correct processes come in.