Title: soldering tqfp-144
Post by: ian on October 10, 2011, 06:36:22 pm
Post by: ian on October 10, 2011, 06:36:22 pm
Quote
I am currently considering Seeed's Fusion board service as an alternative for some pcbs an am working on. Is it any harder to hand solder or stencil a tqfp-144-0.5mm without a large soldermask bridge between the pads, than with one? --Alex
I'm not 100% sure I understand. I have no problem hand soldering tqfp 144 .5mm. I prefer to do it with a nice soldermask, it keeps the solder from bridging as much.
Title: Re: soldering tqfp-144
Post by: arupbsk on October 10, 2011, 07:06:55 pm
Post by: arupbsk on October 10, 2011, 07:06:55 pm
Alex, try a lots of flux and general 60/40 solder. I solder SMD ICs this way and even if solder bridge made, apply few more flux and with soldering iron's tip heat the bridge, the solders will be positioned into pins and bridge will be removed.
This is a great video guide. http://www.youtube.com/watch?v=3NN7UGWYmBY (http://www.youtube.com/watch?v=3NN7UGWYmBY)
This is a great video guide. http://www.youtube.com/watch?v=3NN7UGWYmBY (http://www.youtube.com/watch?v=3NN7UGWYmBY)
Title: Re: soldering tqfp-144
Post by: alextm on October 10, 2011, 07:13:54 pm
Post by: alextm on October 10, 2011, 07:13:54 pm
Sorry, let me be a little more clear. I have some boards from pcb sunday and such, and the soldermask on them is a father distance away from the pads than the fab I currently use for small boards. It looks like that distance will severely effect the solderability of the part. Mostly I was wondering if it Seeed's boards have soldermask between the pins of a 0.5mm part? None of the scans I found here really showed the pins in enough detail to be sure. Or alternately does it make a difference?
Hope that clears things up a bit.
--Alex
arupbsk, I have hand soldered .5mm pitch on boards with a soldermask between the pins.
Hope that clears things up a bit.
--Alex
arupbsk, I have hand soldered .5mm pitch on boards with a soldermask between the pins.
Title: Re: soldering tqfp-144
Post by: arupbsk on October 10, 2011, 07:52:05 pm
Post by: arupbsk on October 10, 2011, 07:52:05 pm
[quote author="alextm"]
arupbsk, I have hand soldered .5mm pitch on boards with a soldermask between the pins.[/quote]
The way I showed using lots of flux works excellent with my homemade PCBs, where I have soldered tqfp100 Ics too. Note that homemade PCBs dont have silk layer or soldermask, they are just copper and PTH.
Try out my method with good quality liquid flux (the one that is not adhesive type when dried), no problem will happen and you'll get nice soldering of the IC.
Believe me I had my first hands on a professionally made SMD PCB just a few days back when I got my free Buspirate PCB. It didn't need that much flux, but flux is a thing that you shouldn't use cheaply. Till then I always soldered SMD in homemade ones without soldermask.
One more tip, use high watt Iron. I have special 8Watt SMD iron which I use for SMD resistors, etc, but for IC I've found my 35Watt classic Iron is best(with modified tip).
arupbsk, I have hand soldered .5mm pitch on boards with a soldermask between the pins.[/quote]
The way I showed using lots of flux works excellent with my homemade PCBs, where I have soldered tqfp100 Ics too. Note that homemade PCBs dont have silk layer or soldermask, they are just copper and PTH.
Try out my method with good quality liquid flux (the one that is not adhesive type when dried), no problem will happen and you'll get nice soldering of the IC.
Believe me I had my first hands on a professionally made SMD PCB just a few days back when I got my free Buspirate PCB. It didn't need that much flux, but flux is a thing that you shouldn't use cheaply. Till then I always soldered SMD in homemade ones without soldermask.
One more tip, use high watt Iron. I have special 8Watt SMD iron which I use for SMD resistors, etc, but for IC I've found my 35Watt classic Iron is best(with modified tip).
Title: Re: soldering tqfp-144
Post by: alextm on October 10, 2011, 10:49:38 pm
Post by: alextm on October 10, 2011, 10:49:38 pm
Yeah I have good flux and a high power iron, so then I guess I don't need to worry about it. My father's homemade boards were barely good enough for through hole parts, so I never have even tried to make my own boards for smd.
Thanks,
Alex
Thanks,
Alex
Title: Re: soldering tqfp-144
Post by: arhi on October 11, 2011, 02:58:54 am
Post by: arhi on October 11, 2011, 02:58:54 am
[quote author="alextm"]Mostly I was wondering if it Seeed's boards have soldermask between the pins of a 0.5mm part? [/quote]
Nope. None of the boards I made using seeed's fusion nor itead's pcb fab (they use same factory) had lot lack between 0.5mm pins
[quote author="alextm"]does it make a difference?[/quote]
yes it does. It is much easier to solder when there is solder mask / lot lack between pins; but as you was already told, it's not too hard to solder tqfp even without solder mask between pins. One important tip, lot of flux is cool but use VERY THIN SOLDER WIRE!!! don't use anything thicker then 0.5mm. 0.3mm is preferable. By using thin wire you can control precisely how much solder you put on the iron and on the device. Also if you can find "mini wave" tip for your iron it works superbly good. Here's how mini wave tip looks like (the dent on the tip is a feature not a bug :D ). Picture is a link to yet another smd soldering tips and tricks site
(http://http://www.sterntech.com/soldering.php)
You can find mini wave tips for all iron brands. I used them with HAKKO, SOLOMON, ISKRA, WELLER .. so mostly every brand out there sell also this type of tips. Some don't have the "dent" and have flat circular surface. Those work also pretty good (I prefer ones with dent)
Nope. None of the boards I made using seeed's fusion nor itead's pcb fab (they use same factory) had lot lack between 0.5mm pins
[quote author="alextm"]does it make a difference?[/quote]
yes it does. It is much easier to solder when there is solder mask / lot lack between pins; but as you was already told, it's not too hard to solder tqfp even without solder mask between pins. One important tip, lot of flux is cool but use VERY THIN SOLDER WIRE!!! don't use anything thicker then 0.5mm. 0.3mm is preferable. By using thin wire you can control precisely how much solder you put on the iron and on the device. Also if you can find "mini wave" tip for your iron it works superbly good. Here's how mini wave tip looks like (the dent on the tip is a feature not a bug :D ). Picture is a link to yet another smd soldering tips and tricks site
(http://http://www.sterntech.com/soldering.php)You can find mini wave tips for all iron brands. I used them with HAKKO, SOLOMON, ISKRA, WELLER .. so mostly every brand out there sell also this type of tips. Some don't have the "dent" and have flat circular surface. Those work also pretty good (I prefer ones with dent)
Title: Re: soldering tqfp-144
Post by: brian on October 11, 2011, 07:37:38 am
Post by: brian on October 11, 2011, 07:37:38 am
[quote author="alextm"] Or alternately does it make a difference?[/quote]
Short answer: No. (With SAC alloy paste).
I assume we are talking about having either the polymer solder mask between the pads or fiberglass (FR4). Both are polymer materials basically and solder shouldn't wet either well.
If there are several bare copper traces next to one another somehow in between the fine pitch tin pads without a mask then yes of course that makes it a lot harder.
Edit: removed link to misleading videos, results remain the same but videos contained factual errors.
Short answer: No. (With SAC alloy paste).
I assume we are talking about having either the polymer solder mask between the pads or fiberglass (FR4). Both are polymer materials basically and solder shouldn't wet either well.
If there are several bare copper traces next to one another somehow in between the fine pitch tin pads without a mask then yes of course that makes it a lot harder.
Edit: removed link to misleading videos, results remain the same but videos contained factual errors.
Title: Re: soldering tqfp-144
Post by: alextm on October 11, 2011, 01:59:25 pm
Post by: alextm on October 11, 2011, 01:59:25 pm
It looks like while there are some differing opinions on how much of a difference it actually makes, I think I should be able to solder this without too much trouble.
brian, those videos were neat, I have seen solder do that on soldermask when I spill paste on it, but never realized FR-4 did that to it as well. I actually have everything here to try to reproduce that, but never thought of trying.
arhi, the wave tips look cool, and I can definitively see the point of those and how they work for controlling the solder. I may have to see if I can pick one of those up for my iron some time soon. That and some finer solder. My tool bench started out for through hole and is only slowly being converted to smd over time.
Everybody here has been quite helpful.
Thank you,
Alex
brian, those videos were neat, I have seen solder do that on soldermask when I spill paste on it, but never realized FR-4 did that to it as well. I actually have everything here to try to reproduce that, but never thought of trying.
arhi, the wave tips look cool, and I can definitively see the point of those and how they work for controlling the solder. I may have to see if I can pick one of those up for my iron some time soon. That and some finer solder. My tool bench started out for through hole and is only slowly being converted to smd over time.
Everybody here has been quite helpful.
Thank you,
Alex
Title: Re: soldering tqfp-144
Post by: arhi on October 11, 2011, 02:01:16 pm
Post by: arhi on October 11, 2011, 02:01:16 pm
donno what kind of test you made but try repeating your test without flux and you'll see lot lack helping a great deal if it's between pads. of course when you do it properly with a lot of flux who cares about what's between them :D
Title: Re: soldering tqfp-144
Post by: arhi on October 11, 2011, 02:08:44 pm
Post by: arhi on October 11, 2011, 02:08:44 pm
[quote author="alextm"]I think I should be able to solder this without too much trouble. [/quote]
just use a lot of flux and you are safe :D and don't make a common mistake of using super fine tip ...
[quote author="alextm"]the wave tips look cool, and I can definitively see the point of those and how they work for controlling the solder. I may have to see if I can pick one of those up for my iron some time soon. That and some finer solder.[/quote]
isn't required but does help a lot. having some wick is helpful too :D
The major problem with 0.5mm pitch is to properly align the part on the board and that's where quality of pcb is important. It is way easier to position part on a good board then on a shitty one
just use a lot of flux and you are safe :D and don't make a common mistake of using super fine tip ...
[quote author="alextm"]the wave tips look cool, and I can definitively see the point of those and how they work for controlling the solder. I may have to see if I can pick one of those up for my iron some time soon. That and some finer solder.[/quote]
isn't required but does help a lot. having some wick is helpful too :D
The major problem with 0.5mm pitch is to properly align the part on the board and that's where quality of pcb is important. It is way easier to position part on a good board then on a shitty one
Title: Re: soldering tqfp-144
Post by: alextm on October 11, 2011, 02:17:53 pm
Post by: alextm on October 11, 2011, 02:17:53 pm
> The major problem with 0.5mm pitch is to properly align the part on the board and that's where quality of pcb is important. It is way easier to position part on a good board then on a shitty one
Oh yes, placing the parts is the most annoying part of soldering. It took me a while after the first time I tried soldering tqfp-0.8 and failed badly to even attempt anything quad again. Thankfully that was several months ago.
I also do have wick and use it constantly.
> don't make a common mistake of using super fine tip
I don't think that will be a problem ;)
Oh yes, placing the parts is the most annoying part of soldering. It took me a while after the first time I tried soldering tqfp-0.8 and failed badly to even attempt anything quad again. Thankfully that was several months ago.
I also do have wick and use it constantly.
> don't make a common mistake of using super fine tip
I don't think that will be a problem ;)
Title: Re: soldering tqfp-144
Post by: sdixon on October 11, 2011, 06:50:34 pm
Post by: sdixon on October 11, 2011, 06:50:34 pm
[quote author="arhi"]
You can find mini wave tips for all iron brands. I used them with HAKKO, SOLOMON, ISKRA, WELLER .. so mostly every brand out there sell also this type of tips. Some don't have the "dent" and have flat circular surface. Those work also pretty good (I prefer ones with dent)[/quote]
I recently went on a search for mini-wave style tips for Hakko or Aoyue irons. What I found was that they are not available for sale in the USA, for patent reasons. In fact, the Hakko site says specifically that their mini-wave style tips are not for sale in the USA. Turns out that Pace has a patent on this style tip and, in the US, you can only get that style tip for Pace equipment. It must be only a US patent since the mini-wave style tips seem to be available elsewhere in the world. Note that by mini-wave style, I mean the ones with the "dent" as Arhi calls it. The flat faced tips are easily available.
In case it isn't apparent, the mini-wave style is supposed to be better for drag soldering because the "dent" serves as a reservoir for solder.
You can find mini wave tips for all iron brands. I used them with HAKKO, SOLOMON, ISKRA, WELLER .. so mostly every brand out there sell also this type of tips. Some don't have the "dent" and have flat circular surface. Those work also pretty good (I prefer ones with dent)[/quote]
I recently went on a search for mini-wave style tips for Hakko or Aoyue irons. What I found was that they are not available for sale in the USA, for patent reasons. In fact, the Hakko site says specifically that their mini-wave style tips are not for sale in the USA. Turns out that Pace has a patent on this style tip and, in the US, you can only get that style tip for Pace equipment. It must be only a US patent since the mini-wave style tips seem to be available elsewhere in the world. Note that by mini-wave style, I mean the ones with the "dent" as Arhi calls it. The flat faced tips are easily available.
In case it isn't apparent, the mini-wave style is supposed to be better for drag soldering because the "dent" serves as a reservoir for solder.
Title: Re: soldering tqfp-144
Post by: arhi on October 11, 2011, 10:03:43 pm
Post by: arhi on October 11, 2011, 10:03:43 pm
I also have for both HAKKO and SOLOMON only ones with flat head as the "dented" ones were not available (ordered via ebay.com but they arrived from far east). Did you manage to find "dented" ones somewhere else (PRC for e.g. ?). The flat ones work great, dented ones would obviously work even better :). Btw I have no idea how to call that "dent" properly in English, so whoever has enough knowledge of English language please step in :D. I don't think "hole" is proper, puddle also ..
Title: Re: soldering tqfp-144
Post by: sdixon on October 11, 2011, 10:32:55 pm
Post by: sdixon on October 11, 2011, 10:32:55 pm
[quote author="arhi"]I also have for both HAKKO and SOLOMON only ones with flat head as the "dented" ones were not available (ordered via ebay.com but they arrived from far east). Did you manage to find "dented" ones somewhere else (PRC for e.g. ?). The flat ones work great, dented ones would obviously work even better :). Btw I have no idea how to call that "dent" properly in English, so whoever has enough knowledge of English language please step in :D. I don't think "hole" is proper, puddle also ..[/quote]
Your english is just fine. I wasn't trying to criticize your choice of words at all. Dent is OK although indentation would probably be more correct but certainly longer.
I never did find any tips except the flat ones (except for tips for Pace irons). Dave Jones (http://www.eevblog.com/2011/07/18/eevbl ... face-mount (http://www.eevblog.com/2011/07/18/eevblog-186-soldering-tutorial-part-3-surface-mount)) has a nice video on surface mount soldering and he also says the indented tips are really the best (he calls the indentation a "well", which sort of makes sense since it holds solder). Of course, he is in Australia and can apparently buy those tips there...
Your english is just fine. I wasn't trying to criticize your choice of words at all. Dent is OK although indentation would probably be more correct but certainly longer.
I never did find any tips except the flat ones (except for tips for Pace irons). Dave Jones (http://www.eevblog.com/2011/07/18/eevbl ... face-mount (http://www.eevblog.com/2011/07/18/eevblog-186-soldering-tutorial-part-3-surface-mount)) has a nice video on surface mount soldering and he also says the indented tips are really the best (he calls the indentation a "well", which sort of makes sense since it holds solder). Of course, he is in Australia and can apparently buy those tips there...
Title: Re: soldering tqfp-144
Post by: arhi on October 11, 2011, 11:04:36 pm
Post by: arhi on October 11, 2011, 11:04:36 pm
I had no feeling you was criticizing it, it's just that I think that "dent" ain't really the proper word and it was the best choice I could come up with :D ... well does sound better then a "puddle" what was my initial choice :D :D :D
maybe we can storm some Australian online seller to send us those tips :D ...
maybe we can storm some Australian online seller to send us those tips :D ...
Title: Re: soldering tqfp-144
Post by: sdixon on October 11, 2011, 11:50:03 pm
Post by: sdixon on October 11, 2011, 11:50:03 pm
Dimpled is a good choice of word for this.
I'm not sure you can punch a dimple of the appropriate size in a flat tip face. If you look at these tips, the dimple is pretty deep and also I think you might damage the plating on the tip, which would destroy it.
I'm not sure you can punch a dimple of the appropriate size in a flat tip face. If you look at these tips, the dimple is pretty deep and also I think you might damage the plating on the tip, which would destroy it.
Title: Re: soldering tqfp-144
Post by: sdixon on October 12, 2011, 12:26:46 am
Post by: sdixon on October 12, 2011, 12:26:46 am
[quote author="arhi"]
maybe we can storm some Australian online seller to send us those tips :D ...[/quote]
It would be nice to find some place which sold them via mail. Of course it might also be possible that Dave Jones just has a Pace iron and that is why he can get the dimpled tips...
maybe we can storm some Australian online seller to send us those tips :D ...[/quote]
It would be nice to find some place which sold them via mail. Of course it might also be possible that Dave Jones just has a Pace iron and that is why he can get the dimpled tips...
Title: Re: soldering tqfp-144
Post by: brian on October 12, 2011, 11:56:49 am
Post by: brian on October 12, 2011, 11:56:49 am
I did a quick follow up experiment to the one I posted about before. For my purposes what I did before was what matters as I do reflow with the paste I used. I do get bridging at times and I wanted to know if it was going to make any difference to have a mask between pins. My conclusion there remains as stated, for how I solder the mask should not matter.
My follow up experiment attempted to address two items:
First does Pb/Sn wet differently (on these materials) than Sn/Ag/Cu?
Second does the flux matter?
What I did was the following:
I took Pb/Sn and SAC and melted them into balls on a PCB.
I moved the balled to a flux free area then smashed them flat as they cooled so they would not be spherical.
I next moved the flat solder to FR4 and mask materials and heated the board up.
All of them turned into spheres again without flux. This means they don't really wet either surface well.
I also moved the solder ball around the surface of each material with each type of alloy. The Pb/Sn subjectively wets both FR4 and the mask better than SAC and would leave streaks if played with long enough. (Rather than always remaining a sphere without flux.) This could mean the oxide can stick or that the flux changes the surface termination. The SAC alloy was a lot less likely to stick to either surface, but did stick eventually to both. I should note the board was degrading at this point from it being on the hot plate so long.
My best guess based on this limited data is that:
The flux helps the solder stick to itself better allowing it to ball up and dewet better. The flux may also change the surface termination, however this would probably interfere with wetting metal joints, so the former seems more likely.
Pb/Sn alloys seem to wet both surfaces much better than SAC alloys.
Solder sticking to FR4 is certainly possible particularly if the board is locally degrading from the temperature.
All alloys and surfaces studied have a contact angle that is greater than 90 degrees (spheres form).
FR4 may wet marginally better without flux than mask material, particularly with Pb/Sn. This may account for the anecdotal reports of the mask being better as most people likely use Pb based solder at home. For SAC the difference is pretty negligible.
My follow up experiment attempted to address two items:
First does Pb/Sn wet differently (on these materials) than Sn/Ag/Cu?
Second does the flux matter?
What I did was the following:
I took Pb/Sn and SAC and melted them into balls on a PCB.
I moved the balled to a flux free area then smashed them flat as they cooled so they would not be spherical.
I next moved the flat solder to FR4 and mask materials and heated the board up.
All of them turned into spheres again without flux. This means they don't really wet either surface well.
I also moved the solder ball around the surface of each material with each type of alloy. The Pb/Sn subjectively wets both FR4 and the mask better than SAC and would leave streaks if played with long enough. (Rather than always remaining a sphere without flux.) This could mean the oxide can stick or that the flux changes the surface termination. The SAC alloy was a lot less likely to stick to either surface, but did stick eventually to both. I should note the board was degrading at this point from it being on the hot plate so long.
My best guess based on this limited data is that:
The flux helps the solder stick to itself better allowing it to ball up and dewet better. The flux may also change the surface termination, however this would probably interfere with wetting metal joints, so the former seems more likely.
Pb/Sn alloys seem to wet both surfaces much better than SAC alloys.
Solder sticking to FR4 is certainly possible particularly if the board is locally degrading from the temperature.
All alloys and surfaces studied have a contact angle that is greater than 90 degrees (spheres form).
FR4 may wet marginally better without flux than mask material, particularly with Pb/Sn. This may account for the anecdotal reports of the mask being better as most people likely use Pb based solder at home. For SAC the difference is pretty negligible.
Title: Re: soldering tqfp-144
Post by: arhi on October 12, 2011, 12:53:59 pm
Post by: arhi on October 12, 2011, 12:53:59 pm
[quote author="sdixon"]
has a Pace iron and that is why he can get the dimpled tips...[/quote]
I was looking at pictures of the PACE stations and they look exactly like Weller stations... any correlation between the two you know off?
[quote author="brian"]
First does Pb/Sn wet differently than Sn/Ag/Cu?
[/quote]
In my very limited experience with SAC it bridges way less then standard 60/40 solder. I had other type of issues with it so I stopped using it but wrt soldering fine pitch parts it was actually easier then "regular" solder (I always preheat the pcb before working on it with soldering iron, heard it helps, never tried without preheating it) - that's of course with soldering iron - I never tried the solder paste that's snagcu
has a Pace iron and that is why he can get the dimpled tips...[/quote]
I was looking at pictures of the PACE stations and they look exactly like Weller stations... any correlation between the two you know off?
[quote author="brian"]
First does Pb/Sn wet differently than Sn/Ag/Cu?
[/quote]
In my very limited experience with SAC it bridges way less then standard 60/40 solder. I had other type of issues with it so I stopped using it but wrt soldering fine pitch parts it was actually easier then "regular" solder (I always preheat the pcb before working on it with soldering iron, heard it helps, never tried without preheating it) - that's of course with soldering iron - I never tried the solder paste that's snagcu
Title: Re: soldering tqfp-144
Post by: arupbsk on October 12, 2011, 09:49:55 pm
Post by: arupbsk on October 12, 2011, 09:49:55 pm
I'll call the tip a 'cavity tip'.
Title: Re: soldering tqfp-144
Post by: brian on October 14, 2011, 03:36:38 am
Post by: brian on October 14, 2011, 03:36:38 am
Leave it to getting on the front page to point out a mistake. If you saw my videos it looks like I was in error and that both the copper and non-copper areas had mask on them. Opps. I should probably refrain from such things past 2 AM!
I did repeat the SAC paste with flux on the edge of 4 PCBs stacked together (sure to be free of mask). It still didn't wet the surface. However I don't want to mislead anyone with the video post so those videos will be pulled tomorrow.
So I still think it will dewet FR4 (at least with flux and SAC) but a more definitive result will have to wait until I have an appropriate PCB!
I did repeat the SAC paste with flux on the edge of 4 PCBs stacked together (sure to be free of mask). It still didn't wet the surface. However I don't want to mislead anyone with the video post so those videos will be pulled tomorrow.
So I still think it will dewet FR4 (at least with flux and SAC) but a more definitive result will have to wait until I have an appropriate PCB!
Title: Re: soldering tqfp-144
Post by: Sjaak on October 14, 2011, 09:10:24 am
Post by: Sjaak on October 14, 2011, 09:10:24 am
Just to step in the discussion about soldermask (a bit late)
I guess if you have soldermask between the pins, you have a little barriere between the pins (the soldermask). DUnno if that makes a big difference in soldering, but I guess it will help.
I guess if you have soldermask between the pins, you have a little barriere between the pins (the soldermask). DUnno if that makes a big difference in soldering, but I guess it will help.
Title: Re: soldering tqfp-144
Post by: bearmos on October 14, 2011, 01:54:45 pm
Post by: bearmos on October 14, 2011, 01:54:45 pm
[quote author="arhi"]In my very limited experience with SAC it bridges way less then standard 60/40 solder. I had other type of issues with it so I stopped using it but wrt soldering fine pitch parts it was actually easier then "regular" solder[/quote]
I had read somewhere (trade mag perhaps) that lead free solder is the *only* way to solder some of the super fine-pitch components - since it doesn't wet as well, you wind up with fewer bridges, whereas leaded solder would simply bridge the connections. Ironically enough, these same fine pitch components are the same area where tin whiskers present the biggest issue - they create(d) bridges after the board is assembled! I think the tin whiskers fiasco is sorted out by now (I'm currently designing boards under a RoHS exemption), but I think NASA probably still prefers the leaded variety of solder.
I had read somewhere (trade mag perhaps) that lead free solder is the *only* way to solder some of the super fine-pitch components - since it doesn't wet as well, you wind up with fewer bridges, whereas leaded solder would simply bridge the connections. Ironically enough, these same fine pitch components are the same area where tin whiskers present the biggest issue - they create(d) bridges after the board is assembled! I think the tin whiskers fiasco is sorted out by now (I'm currently designing boards under a RoHS exemption), but I think NASA probably still prefers the leaded variety of solder.
Title: Re: soldering tqfp-144
Post by: arhi on October 14, 2011, 02:01:59 pm
Post by: arhi on October 14, 2011, 02:01:59 pm
AFAIK anything that goes into space is still leaded becase lead free solder grow whiskers at increased rate when in space (donno if it's the lack of gravitation or something else, but I remember seeing a movie while back showing in real time how they grow and make bridges).
Donno if whiskers issue is solved as I know there is a number of lead free soldering mixtures today ... I'm using leaded solder at home - I do try to use rohs components but I do solder them with lead...
Donno if whiskers issue is solved as I know there is a number of lead free soldering mixtures today ... I'm using leaded solder at home - I do try to use rohs components but I do solder them with lead...
Title: Re: soldering tqfp-144
Post by: rsdio on October 16, 2011, 12:40:10 pm
Post by: rsdio on October 16, 2011, 12:40:10 pm
[quote author="bearmos"]Ironically enough, these same fine pitch components are the same area where tin whiskers present the biggest issue - they create(d) bridges after the board is assembled! I think the tin whiskers fiasco is sorted out by now (I'm currently designing boards under a RoHS exemption), but I think NASA probably still prefers the leaded variety of solder.[/quote]
I did some brief online research about leaded and lead-free solder, and the consensus I seemed to find was that the problems are not present with the good quality lead-free solder. The real problem is the cheap stuff.
Of course, now I'm looking at Silver solder, buy Fry's Electronics is always sold out every time I go. I think that jewelry makers are buying it up. I also notice that Sunstone Circuits will finish a board with RoHS Silver solder at no extra charge compared to Tin Lead.
Problem is, you don't want to mix types of solder, so you'd better coordinate from PCB fab to assembly to repair.
I did some brief online research about leaded and lead-free solder, and the consensus I seemed to find was that the problems are not present with the good quality lead-free solder. The real problem is the cheap stuff.
Of course, now I'm looking at Silver solder, buy Fry's Electronics is always sold out every time I go. I think that jewelry makers are buying it up. I also notice that Sunstone Circuits will finish a board with RoHS Silver solder at no extra charge compared to Tin Lead.
Problem is, you don't want to mix types of solder, so you'd better coordinate from PCB fab to assembly to repair.