Homebrew PCBs

How does everyone hold down the SMT parts prior to hand soldering?

What type of adhesive is used to hold the SMT parts?

Where can I get(I am in the USA) it?

Thank you,

Martin

Hi Martin,

This is what I do. I've never had any formal training, so my technique
might not be the best, in which case, I'm sure that one of the more
knowledgeable members will correct me :)

I use liquid flux. I paint the pads with it. It's slightly tacky. If
that's not enough, then I use a pair of tweezers to apply pressure from
the top and use a very small amount of solder on the tip of the iron.
This is typically good enough for tacking purposes. You're supposed to
heat the part and apply the solder to the part, rather than putting the
solder on the tip, but with one hand holding the tweezers and one hald
holding the soldering iron, there's no hands to hold the solder.

Once the part is tacked down and everything lines up properly, I
properly solder the remaining pins, and then come back and redo the
original tack.

You can get liquid flux in a pen from Digikey. I also got a bottle from
my local electronics supplier.

--
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/ 

> -----Original Message-----
> From: mava3941 [mailto:mava3941@...] 
> Sent: Tuesday, June 15, 2004 5:43 PM
> To: Homebrew_PCBs@yahoogroups.com
> Subject: [Homebrew_PCBs] How does everyone hold down SMT parts
> 
> 
> How does everyone hold down the SMT parts prior to hand soldering?
> 
> What type of adhesive is used to hold the SMT parts?
> 
> Where can I get(I am in the USA) it?
> 
> Thank you,
> 
> Martin

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

From: "Dave Hylands" <dhylands@...>
To: <Homebrew_PCBs@yahoogroups.com>
Sent: Wednesday, June 16, 2004 5:33 AM
Subject: RE: [Homebrew_PCBs] How does everyone hold down SMT parts


> Hi Martin,
>
> This is what I do. I've never had any formal training, so my technique
> might not be the best, in which case, I'm sure that one of the more
> knowledgeable members will correct me :)
>
> I use liquid flux. I paint the pads with it. It's slightly tacky. If
> that's not enough, then I use a pair of tweezers to apply pressure from
> the top and use a very small amount of solder on the tip of the iron.
> This is typically good enough for tacking purposes. You're supposed to
> heat the part and apply the solder to the part, rather than putting the
> solder on the tip, but with one hand holding the tweezers and one hald
> holding the soldering iron, there's no hands to hold the solder.
>
> Once the part is tacked down and everything lines up properly, I
> properly solder the remaining pins, and then come back and redo the
> original tack.
>
> You can get liquid flux in a pen from Digikey. I also got a bottle from
> my local electronics supplier.

That's how I do it, as well. I use a stereo microscope for devices with
really fine pitch leads, like 0.5 mm QFP parts.

Leon

On Wed, 16 Jun 2004 00:43:26 -0000, mava3941 <mava3941@...> wrote:

> How does everyone hold down the SMT parts prior to hand soldering?
>
> What type of adhesive is used to hold the SMT parts?
>
> Where can I get(I am in the USA) it?
>
> Thank you,
>
> Martin


the glue is only needed for industrial appliation when one side is 
soldered upside down.

you can use the described solder tacking.
a member here (sorry, the name ...) has invented a ingenious tool 
consisting of a wood
plate and a steel wire spring. the pcb is placed on the plate and the 
spring is bent in an arch.
one side is fixed to the board, the other presses the part down.

I would really recommend solder paste and oven / hot air soldering.
the big advantage is the parts "self align" as they "swim" on the solder.
(solder has a high surface tension).
it is much faster and the result is better in my opinion (hand soldering 
can shock parts and damage them).
I use a heatgun, not an oven, to get best results.
you can build a simple vacuum pickup tool for placement. the paste is 
dispensed
 from a syringe.

ST

Hi Stefan 

How do you solder using a heat Gun ?
what type do you use and what temperature ?
I never used this method but if I could do it with the heat gun would 
be great. do you have some sort of " how to " guide ?
best regards
            Luis



--- In Homebrew_PCBs@yahoogroups.com, Stefan Trethan 
<stefan_trethan@g...> wrote:
> On Wed, 16 Jun 2004 00:43:26 -0000, mava3941 <mava3941@y...> wrote:
> 
> > How does everyone hold down the SMT parts prior to hand soldering?
> >
> > What type of adhesive is used to hold the SMT parts?
> >
> > Where can I get(I am in the USA) it?
> >
> > Thank you,
> >
> > Martin
> 
> 
> the glue is only needed for industrial appliation when one side is 
> soldered upside down.
> 
> you can use the described solder tacking.
> a member here (sorry, the name ...) has invented a ingenious tool 
> consisting of a wood
> plate and a steel wire spring. the pcb is placed on the plate and 
the 
> spring is bent in an arch.
> one side is fixed to the board, the other presses the part down.
> 
> I would really recommend solder paste and oven / hot air soldering.
> the big advantage is the parts "self align" as they "swim" on the 
solder.
> (solder has a high surface tension).
> it is much faster and the result is better in my opinion (hand 
soldering 
> can shock parts and damage them).
> I use a heatgun, not an oven, to get best results.
> you can build a simple vacuum pickup tool for placement. the paste 
is 

> dispensed
>  from a syringe.
> 
> ST

On Wed, 16 Jun 2004 06:51:36 -0000, luismoreira_2004 <luis.moreira@...> 
wrote:

> Hi Stefan
>
> How do you solder using a heat Gun ?
> what type do you use and what temperature ?
> I never used this method but if I could do it with the heat gun would
> be great. do you have some sort of " how to " guide ?
> best regards
>             Luis
>

350 to 400 degree, 20-30cm over the board, vertical, on low volume setting
to prevent blowing the parts away.

I use a expensive steinel lcd but for this porpose i think a cheaper would 
do (distance
sets temp.)

no time now for details, must leave, will write in the evening.

(if you say i must i will write a few html pages about the things i repeat 
1000 times here...)

ST

Gentelmen,

Thank you all.. You got my wheels turnning.

I need to go play with PCBs,Solder,SMT parts & Flux...

Martin