[EE] Hand soldering fine pitch packages

classic Classic list List threaded Threaded
12 messages Options
Reply | Threaded
Open this post in threaded view
|

[EE] Hand soldering fine pitch packages

Bob Blick-5
What I describe may already be a common practice, but it's something I've just recently started doing.

When hand soldering an IC, something like a 0.5mm pitch LQFP, I would usually tack a couple of pins down, maybe brush on a little liquid flux, solder the rest of the pins as best I could, then clear all the shorts and even the soldering out with solder wick. Then clean the flux off and inspect.

But lately what I do is skip the soldering part, just go straight to the solder wick. The wick needs to have some solder on it. In other words, apply the solder with the product meant to remove solder.

Anyway, I've found it to be faster and cleaner, and uses less solder and less solder wick.

And, of course, buy the most expensive solder wick you can find.

Cheers,
Bob
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Reply | Threaded
Open this post in threaded view
|

Re: [EE] Hand soldering fine pitch packages

Randy Dawson
What works for me, is the liquid flux, the water soluble stuff that smells like citrus.
Tack the corner pins, as you suggest.

Then you can 'rake' the iron down the side of the package, no solder required if the PCB is tined.
Solder surface tension solders all the pins without shorts.

Randy

________________________________
From: [hidden email] <[hidden email]> on behalf of Bob Blick <[hidden email]>
Sent: Thursday, September 24, 2020 11:30 AM
To: Microcontroller discussion list - Public. <[hidden email]>
Subject: [EE] Hand soldering fine pitch packages

What I describe may already be a common practice, but it's something I've just recently started doing.

When hand soldering an IC, something like a 0.5mm pitch LQFP, I would usually tack a couple of pins down, maybe brush on a little liquid flux, solder the rest of the pins as best I could, then clear all the shorts and even the soldering out with solder wick. Then clean the flux off and inspect.

But lately what I do is skip the soldering part, just go straight to the solder wick. The wick needs to have some solder on it. In other words, apply the solder with the product meant to remove solder.

Anyway, I've found it to be faster and cleaner, and uses less solder and less solder wick.

And, of course, buy the most expensive solder wick you can find.

Cheers,
Bob
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Reply | Threaded
Open this post in threaded view
|

Re: [EE] Hand soldering fine pitch packages

Neil
In reply to this post by Bob Blick-5
That's mostly what I do for SSOP's and LQFP's... tack, align/tweak,
flood solder, wick, then de-flux.
I don't even add flux anywhere because I'm flood soldering.
Some years ago, I went through an eval of several different wicks (as
I've done for solders, solder pastes, tweezers, flush cutters, etc ;) )
and found one that worked great without adding flux... Techspray 1821
(for no-clean flux).  I don't know if it's the most expensive, but it's
the functionally best one I've found for my uses.

Cheers,
-Neil.




On 9/24/2020 2:30 PM, Bob Blick wrote:

> What I describe may already be a common practice, but it's something I've just recently started doing.
>
> When hand soldering an IC, something like a 0.5mm pitch LQFP, I would usually tack a couple of pins down, maybe brush on a little liquid flux, solder the rest of the pins as best I could, then clear all the shorts and even the soldering out with solder wick. Then clean the flux off and inspect.
>
> But lately what I do is skip the soldering part, just go straight to the solder wick. The wick needs to have some solder on it. In other words, apply the solder with the product meant to remove solder.
>
> Anyway, I've found it to be faster and cleaner, and uses less solder and less solder wick.
>
> And, of course, buy the most expensive solder wick you can find.
>
> Cheers,
> Bob

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Reply | Threaded
Open this post in threaded view
|

Re: [EE] Hand soldering fine pitch packages

K S-7
In reply to this post by Bob Blick-5
I flood (like really flood) the entire row with solder, let it set, then
place the PCB on its edge so the row is now vertical and slowly remelt the
solder from top to bottom. The surface tension collects the excess on the
way down and usually, for a 0.4mm pitch, only the last 2 or 3 pins require
a touch-up with wick. For all four rows of a 120 pin QFP this usually takes
a lot less time than the aligning part. Extra flux not usually required.
Make sure you don't drop the molten blob of solder at the end on other
parts of the board.
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Reply | Threaded
Open this post in threaded view
|

Re: [EE] Hand soldering fine pitch packages

Bob Blick-5
Give my method a try sometime. It uses far less solder and solder wick, but the real advantage for me is less cleanup. Flood filling adds a lot of burned flux. With my method, you only need to use a little bit of flux, and the solder on the wick has no remaining flux. And while you are dragging the wick, it's doing the soldering and pulling some of the fresh hot flux away.

Anyway, I suggest giving it a try. So far I haven't decided which direction to face the wick works best, facing in, out, or sideways from the part.

Friendly regards, Bob

________________________________________
From: [hidden email] <[hidden email]> on behalf of K S
Sent: Thursday, September 24, 2020 2:49 PM
To: Microcontroller discussion list - Public.
Subject: Re: [EE] Hand soldering fine pitch packages

I flood (like really flood) the entire row with solder, let it set, then
place the PCB on its edge so the row is now vertical and slowly remelt the
solder from top to bottom. The surface tension collects the excess on the
way down and usually, for a 0.4mm pitch, only the last 2 or 3 pins require
a touch-up with wick. For all four rows of a 120 pin QFP this usually takes
a lot less time than the aligning part. Extra flux not usually required.
Make sure you don't drop the molten blob of solder at the end on other
parts of the board.
--

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Reply | Threaded
Open this post in threaded view
|

Re: [EE] Hand soldering fine pitch packages

Neil
I run the length of the wick across all the pins, then drag the
soldering tip across the wick, while lifting the wick perpendicularly
away from pins.
But NEVER sliding the wick on the pins, as that will catch the pins and
bent them very easily.




On 9/24/2020 6:24 PM, Bob Blick wrote:

> Give my method a try sometime. It uses far less solder and solder wick, but the real advantage for me is less cleanup. Flood filling adds a lot of burned flux. With my method, you only need to use a little bit of flux, and the solder on the wick has no remaining flux. And while you are dragging the wick, it's doing the soldering and pulling some of the fresh hot flux away.
>
> Anyway, I suggest giving it a try. So far I haven't decided which direction to face the wick works best, facing in, out, or sideways from the part.
>
> Friendly regards, Bob
>
> ________________________________________
> From: [hidden email] <[hidden email]> on behalf of K S
> Sent: Thursday, September 24, 2020 2:49 PM
> To: Microcontroller discussion list - Public.
> Subject: Re: [EE] Hand soldering fine pitch packages
>
> I flood (like really flood) the entire row with solder, let it set, then
> place the PCB on its edge so the row is now vertical and slowly remelt the
> solder from top to bottom. The surface tension collects the excess on the
> way down and usually, for a 0.4mm pitch, only the last 2 or 3 pins require
> a touch-up with wick. For all four rows of a 120 pin QFP this usually takes
> a lot less time than the aligning part. Extra flux not usually required.
> Make sure you don't drop the molten blob of solder at the end on other
> parts of the board.
> --
>

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Reply | Threaded
Open this post in threaded view
|

Re: [EE] Hand soldering fine pitch packages

K S-7
In reply to this post by Bob Blick-5
> Give my method a try sometime. It uses far less solder and solder wick,
>

I did actually use this method prior to what I do now, and continue to use
it for rework if I can't be bothered reworking a whole row - the method I
described only works well on whole rows. I really saturate the wick with
solder and keep the end nicely trimmed.

The main reason I went to the method I described is because I find it gives
neater and fuller fillets of solder with greater uniformity - the finished
product looks better than a reflowed part. The wicking method, to me at
least, seems to leave thinner and less rounded fillets, and the consistency
is very dependent on wicking time, etc. I'm sure with enough care this is
all cosmetic and none of it matters.

It also depends on what else is around the part. The wicking method is
sometimes hampered by proximate parts right near the row of pins, the
"surface tension vs gravity method" is sometimes hampered by complex
happenings at either end of the row.

>
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Reply | Threaded
Open this post in threaded view
|

Re: [EE] Hand soldering fine pitch packages

Manu Abraham-2
In reply to this post by Bob Blick-5
Hi Bob,

On Fri, Sep 25, 2020 at 12:03 AM Bob Blick <[hidden email]> wrote:
>
> What I describe may already be a common practice, but it's something I've just recently started doing.
>
> When hand soldering an IC, something like a 0.5mm pitch LQFP, I would usually tack a couple of pins down, maybe brush on a little liquid flux, solder the rest of the pins as best I could, then clear all the shorts and even the soldering out with solder wick. Then clean the flux off and inspect.
>
> But lately what I do is skip the soldering part, just go straight to the solder wick. The wick needs to have some solder on it. In other words, apply the solder with the product meant to remove solder.
>
> Anyway, I've found it to be faster and cleaner, and uses less solder and less solder wick.


There 's one more aspect you might not have realized. With that procedure,
even when you have components with oxidized pins, the solder process is easier.
The heat + the abrasive effect of the wick does the trick most of the times.
Tacking a few pins at some points do help improve how much abrasion you can
cause though.

Cheers,

Manu

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Reply | Threaded
Open this post in threaded view
|

Re: [EE] Hand soldering fine pitch packages

madscientistatlarge
In reply to this post by K S-7
What are people doing for parts with a thermal pad?  I.e. can one just put a dab of solder paste on the pad or is it mandatory to use a stencil?


Sent with ProtonMail Secure Email.

‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
On Thursday, September 24, 2020 4:59 PM, K S <[hidden email]> wrote:

> > Give my method a try sometime. It uses far less solder and solder wick,
>
> I did actually use this method prior to what I do now, and continue to use
> it for rework if I can't be bothered reworking a whole row - the method I
> described only works well on whole rows. I really saturate the wick with
> solder and keep the end nicely trimmed.
>
> The main reason I went to the method I described is because I find it gives
> neater and fuller fillets of solder with greater uniformity - the finished
> product looks better than a reflowed part. The wicking method, to me at
> least, seems to leave thinner and less rounded fillets, and the consistency
> is very dependent on wicking time, etc. I'm sure with enough care this is
> all cosmetic and none of it matters.
>
> It also depends on what else is around the part. The wicking method is
> sometimes hampered by proximate parts right near the row of pins, the
> "surface tension vs gravity method" is sometimes hampered by complex
> happenings at either end of the row.
>
> >
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist



--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Reply | Threaded
Open this post in threaded view
|

Re: [EE] Hand soldering fine pitch packages

Neil
I put a large via/hole under the chip and solder that from the back.
Just a bit more challenging to remove, even with hot air.

Cheers,
-Neil


On 9/25/2020 12:58 PM, madscientistatlarge wrote:

> What are people doing for parts with a thermal pad?  I.e. can one just put a dab of solder paste on the pad or is it mandatory to use a stencil?
>
>
> Sent with ProtonMail Secure Email.
>
> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> On Thursday, September 24, 2020 4:59 PM, K S <[hidden email]> wrote:
>
>>> Give my method a try sometime. It uses far less solder and solder wick,
>> I did actually use this method prior to what I do now, and continue to use
>> it for rework if I can't be bothered reworking a whole row - the method I
>> described only works well on whole rows. I really saturate the wick with
>> solder and keep the end nicely trimmed.
>>
>> The main reason I went to the method I described is because I find it gives
>> neater and fuller fillets of solder with greater uniformity - the finished
>> product looks better than a reflowed part. The wicking method, to me at
>> least, seems to leave thinner and less rounded fillets, and the consistency
>> is very dependent on wicking time, etc. I'm sure with enough care this is
>> all cosmetic and none of it matters.
>>
>> It also depends on what else is around the part. The wicking method is
>> sometimes hampered by proximate parts right near the row of pins, the
>> "surface tension vs gravity method" is sometimes hampered by complex
>> happenings at either end of the row.
>>
>> --
>> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
>> View/change your membership options at
>> http://mailman.mit.edu/mailman/listinfo/piclist
>
>

--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Reply | Threaded
Open this post in threaded view
|

Re: [EE] Hand soldering fine pitch packages

Sean Breheny
In reply to this post by madscientistatlarge
It definitely can be done without a stencil.

On Fri, Sep 25, 2020 at 12:59 PM madscientistatlarge <
[hidden email]> wrote:

> What are people doing for parts with a thermal pad?  I.e. can one just put
> a dab of solder paste on the pad or is it mandatory to use a stencil?
>
>
> Sent with ProtonMail Secure Email.
>
> ‐‐‐‐‐‐‐ Original Message ‐‐‐‐‐‐‐
> On Thursday, September 24, 2020 4:59 PM, K S <[hidden email]> wrote:
>
> > > Give my method a try sometime. It uses far less solder and solder wick,
> >
> > I did actually use this method prior to what I do now, and continue to
> use
> > it for rework if I can't be bothered reworking a whole row - the method I
> > described only works well on whole rows. I really saturate the wick with
> > solder and keep the end nicely trimmed.
> >
> > The main reason I went to the method I described is because I find it
> gives
> > neater and fuller fillets of solder with greater uniformity - the
> finished
> > product looks better than a reflowed part. The wicking method, to me at
> > least, seems to leave thinner and less rounded fillets, and the
> consistency
> > is very dependent on wicking time, etc. I'm sure with enough care this is
> > all cosmetic and none of it matters.
> >
> > It also depends on what else is around the part. The wicking method is
> > sometimes hampered by proximate parts right near the row of pins, the
> > "surface tension vs gravity method" is sometimes hampered by complex
> > happenings at either end of the row.
> >
> > >
> >
> > --
> > http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> > View/change your membership options at
> > http://mailman.mit.edu/mailman/listinfo/piclist
>
>
>
> --
> http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
Reply | Threaded
Open this post in threaded view
|

Re: [EE] Hand soldering fine pitch packages

Isaac Marino Bavaresco-2
In reply to this post by madscientistatlarge
>>What are people doing for parts with a thermal pad? I.e. can one just put a dab of solder paste on the pad or is it mandatory to use a stencil?


With the soldering iron I apply a dab of solder to the board's and the IC"s thermal pads. Then I use a hot air gun to heat the board from below, and with tweezers I hold the IC in front of the nozzle until it is hot enough, then I place it over its place on the board, adjusting its position and pressing it down a little. The excess solder just forms a ball at the border of the body.

When the IC is correctly positioned, I turn the gun off and wait a little, until the solder solidifies, then I solder the regular pads around the IC.

Cheers,
Isaac
--
Enviado de meu dispositivo Android com K-9 mail. Desculpe-me pela brevidade.
--
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist