|
Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets. |
|
Thread Tools |
24th May 2017, 8:51 am | #1 |
Heptode
Join Date: Jul 2014
Location: Boston, Lincolnshire, UK.
Posts: 992
|
Solder defect - what is it / causes it ?
Just curious as to what causes the solder defect in the attached photo (a Linn Valhalla PS board) ?
I'm referring to the 'rippling' effect which seems to be present on most of the tracks - I've seen it on other Valhalla boards, but never been sure what causes it - but I'm sure someone here does... Alan |
24th May 2017, 9:05 am | #2 |
Dekatron
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
|
Re: Solder defect - what is it / causes it ?
It's the solder mask rippling. This is completely normal and harmless. You will find this present in a lot of things to be honest. It's annoying however. I don't think the solder masks they use these days do that.
|
24th May 2017, 9:09 am | #3 |
Dekatron
Join Date: May 2008
Location: Derby, UK.
Posts: 7,735
|
Re: Solder defect - what is it / causes it ?
That looks as though it was non-selectively tinned, i.e. tinned before the solder mask was applied. When the board is wave-soldered, the tinning can distort behind the mask.
When I worked in the industry, we always specified selective tinning -- only the exposed copper was tinned.
__________________
If I have seen further than others, it is because I was standing on a pile of failed experiments. |
24th May 2017, 9:17 am | #4 |
Dekatron
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
|
Re: Solder defect - what is it / causes it ?
Much prefer when it is tinned before mask. It's amazing how quickly copper disappears if you don't tin it and damage the mask during a repair. My short spell in a defence contractor repairing things suggested it was probably better to tin the whole board and not bother with the mask. Easier inspection!
|
24th May 2017, 9:32 am | #5 |
Heptode
Join Date: Jul 2014
Location: Boston, Lincolnshire, UK.
Posts: 992
|
Re: Solder defect - what is it / causes it ?
So it's essentially solder 'flowing' unevenly along the tinned tracks, under the mask ? or is it more a thermal effect / distortion of the tinning itself ?
|
24th May 2017, 9:50 am | #6 | |
Dekatron
Join Date: Nov 2010
Location: Oxford, UK.
Posts: 4,941
|
Re: Solder defect - what is it / causes it ?
Quote:
It is made a little less difficult by the fact that top and bottom layers cannot have tracks - they have to be buried in inner layers. So the top and bottom have only component pads and vias on them. |
|
24th May 2017, 10:42 am | #7 |
Dekatron
Join Date: Jun 2016
Location: London, UK.
Posts: 3,687
|
Re: Solder defect - what is it / causes it ?
Indeed. I've done some SMD prototyping and it's difficult with knife cut boards and no mask as the solder just floods all over the place.
All the boards for repair I had failed were due to cracked vias. That would scare me in high reliability applications. Might have just been the crappy in house production line though. Oh and some idiot soldering packages the wrong way round. I hated reworking big DIP packages. |
26th May 2017, 9:53 pm | #8 | |
Nonode
Join Date: Aug 2007
Location: Walsall Wood, Aldridge, Walsall, UK.
Posts: 2,853
|
Re: Solder defect - what is it / causes it ?
Hi!
Quote:
Chris Williams
__________________
It's an enigma, that's what it is! This thing's not fixed because it doesn't want to be fixed! |
|