Homebrew PCBs

I've just received a cheap (75 GBP) stereo dissecting microscope I ordered
for SMD assembly - I use a lot of fine pitch devices with 0.5 mm lead
spacing (not on home-made PCBs, of course).

Looking at some of my boards through it I can see that my soldering
techniques need a lot improvement - it's surprising that I can get anything
to work. 8-)

Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html

On Thu, 8 Jan 2004 14:23:23 -0000, Leon Heller <leon_heller@...> 
wrote:

> I've just received a cheap (75 GBP) stereo dissecting microscope I 
> ordered
> for SMD assembly - I use a lot of fine pitch devices with 0.5 mm lead
> spacing (not on home-made PCBs, of course).
>
> Looking at some of my boards through it I can see that my soldering
> techniques need a lot improvement - it's surprising that I can get 
> anything
> to work. 8-)
>
> Leon
> --

I'd rather not look at my boards then ;-)

do you solder them with hot air? i suppose that is best?

maybe baking in a oven is better...

Has anyone built one yet? we discussed that some time ago?
maybe some time i would like to have one......

ST

----- Original Message ----- 

From: "Stefan Trethan" <stefan_trethan@...>
To: <homebrew_pcbs@yahoogroups.com>
Sent: Thursday, January 08, 2004 3:49 PM
Subject: Re: [Homebrew_PCBs] Microscope / smd soldering


> On Thu, 8 Jan 2004 14:23:23 -0000, Leon Heller <leon_heller@...>
> wrote:
>
> > I've just received a cheap (75 GBP) stereo dissecting microscope I
> > ordered
> > for SMD assembly - I use a lot of fine pitch devices with 0.5 mm lead
> > spacing (not on home-made PCBs, of course).
> >
> > Looking at some of my boards through it I can see that my soldering
> > techniques need a lot improvement - it's surprising that I can get
> > anything
> > to work. 8-)
> >
> > Leon
> > --
>
> I'd rather not look at my boards then ;-)
>
> do you solder them with hot air? i suppose that is best?

I recently got a refurbished Metcal soldering station with a 'mini hoof' tip
for drag soldering fine pitch parts. That make it quite easy. The microscope
is for getting the chip correctly positioned and tacked down by the corner
leads.

Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html

>
> I recently got a refurbished Metcal soldering station with a 'mini hoof' 
> tip
> for drag soldering fine pitch parts. That make it quite easy. The 
> microscope
> is for getting the chip correctly positioned and tacked down by the 
> corner
> leads.
>
> Leon
> --

The trick with hot air or ovens is that it aligns the part itself.
you just need to place it in about the right spot and the surface tension
of the solder will align it properly.

Stefan

----- Original Message ----- 

From: "Stefan Trethan" <stefan_trethan@...>
To: <homebrew_pcbs@yahoogroups.com>
Sent: Thursday, January 08, 2004 5:36 PM
Subject: Re: [Homebrew_PCBs] Microscope / smd soldering


>
> >
> > I recently got a refurbished Metcal soldering station with a 'mini hoof'
> > tip
> > for drag soldering fine pitch parts. That make it quite easy. The
> > microscope
> > is for getting the chip correctly positioned and tacked down by the
> > corner
> > leads.
> >
> > Leon
> > --
>
> The trick with hot air or ovens is that it aligns the part itself.
> you just need to place it in about the right spot and the surface tension
> of the solder will align it properly.


I've thought of doing that, but the Metcal tip makes it much quicker. They
have an tech note on the technique:

http://www.metcal.com/tips/minihoof.html

I've used a similar technique in the past with an ordinary soldering station
and tip, using lots of flux and solder, then cleaning up with desoldering
braid.

Leon
--
Leon Heller, G1HSM
Email: aqzf13@...
My low-cost Philips LPC210x ARM development system:
http://www.geocities.com/leon_heller/lpc2104.html

>
> I've thought of doing that, but the Metcal tip makes it much quicker. 
> They
> have an tech note on the technique:
>
> http://www.metcal.com/tips/minihoof.html
>
> I've used a similar technique in the past with an ordinary soldering 
> station
> and tip, using lots of flux and solder, then cleaning up with desoldering
> braid.
>
> Leon

I see..

still the method with the oven seems quite fast to me..

they just apply a line of solder paste across all the pins and
it sucks itself where it belongs.

I once did a smd board with that oven method, it used no ics, only 1206 and 
0804.
you have to apply a small drop of solder paste on each pad seperately here, 
i think it was still much faster than soldering with a iron.

If you have a board with, say 5, 100 pin ics it may save quite some time.

sure, the solder paste is relatively expensive.
that keeps me from using the method.

but i really think it is very convenient if you need it often.


Stefan

I tend to use both.  The caps and other "jellybeans" get hot air 
soldered, while I still use the solder iron "drag" technique to get 
the fine pitch ic's down.  It's difficult to do 805 ceramic caps with 
an iron; they tend to develop cracks if not heated correctly.

BTW, I just got my mono video microscope yesterday.  I thought the 
200x would be too high, but it actually works pretty well for what I 
want to do with it.  On my 100pin tqfp's it shows 10 or so pins on 
the screen at a time, and actually has a little focal depth.   For 
$35, it's not too bad; although I'd trade anyone who wanted to swap 
their stereo bench microscope anytime.

http://www.compgeeks.com/details.asp?invtid=BMC2150-PB

-Dal