Good Morning,
      I believe that surface Measling is caused from excess  heat.
 You should check your iron tip for size compared to land and terminal.
Then  make sure that the iron is coated with solder at all times to prevent oxidation build up.
I would think that you are having a problem with transferring the heat from the iron to the land.
Therefore you may be holding the iron to long on the pad.
Well this may be enough to get you started.
Hope this helps and that I didn't lead you in the wrong direction.
Have a good day.
Nancy T.
 

>>> Goh Guan Chye <[log in to unmask]> 01/31/00 04:27AM >>>
Hi ! Technetters,

May anyone advise a measling problem after manual soldering.

We have a batch of PCBA spotted with measling after manual soldering.
These measling happen surround the areas with large copper plane. This
is a 14-layer design (2.9mm thick) with 6 layers of large copper areas
(not full plane). Due to heat sinking problem, we use solder temperature
of 350 degC and the soldering duration is about 2-3 secs. To analyse on
the problem, we wave the assembly at solder bath temp of 250 degC, no
measling found.

The question now is, this is not the first time that we manual solder
high layer count MLB with large copper plane. We did not find any
measling problem. In such case, what could it be due to ? The bare board
quality problem ? Should the bare board must be able to withstand the
manual soldering that we used ?

If the measling doesn't meet the IPC acceptance criteria, would it
affect the bare board's reliability ?

Thanks for your attention and have a nice day.

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