Small-volume SMD setup?

[Mike Rocket J Squirrel]

This is not a CAD question, my apologies to those with limited bandwidth.

On occasion, we need to produce small runs of boards with surface-mount
parts. We do through-hole boards by hand day in and day out, but
surface-mount tech is a mystery to me, so we offload them to a local
assembly house. I don't mind paying other folks to do stuff that we
don't want to get into, like powder-coating, painting, fabbing pcbs,
etc., but it kinda rankles me to pay to have someone build up boards
just because I don't know how to do them myself.

Are there turnkey SMD assembly systems for small-volume work? I assume
we'd need a way to screen paste onto the boards, smoosh the parts on,
then flow the solder. There -- I've shown how little I understand.

-- mike elliott

 

[Boris Mohar]

On Fri, 21 Jul 2006 06:54:32 -0700, Mike Rocket J Squirrel
<j.michael.elliott@GOLLYgmail.com> wrote:

This is not a CAD question, my apologies to those with limited bandwidth.

On occasion, we need to produce small runs of boards with surface-mount
parts. We do through-hole boards by hand day in and day out, but
surface-mount tech is a mystery to me, so we offload them to a local
assembly house. I don't mind paying other folks to do stuff that we
don't want to get into, like powder-coating, painting, fabbing pcbs,
etc., but it kinda rankles me to pay to have someone build up boards
just because I don't know how to do them myself.

Are there turnkey SMD assembly systems for small-volume work? I assume
we'd need a way to screen paste onto the boards, smoosh the parts on,
then flow the solder. There -- I've shown how little I understand.

-- mike elliott

Some have gone this route

http://www.beloev.net/gbvio.html

Google toaster oven SMD for more



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

void _-void-_ in the obvious place



--
Posted via a free Usenet account from http://www.teranews.com

 

[Paul Burke]

Mike Rocket J Squirrel wrote:

This is not a CAD question, my apologies to those with limited bandwidth.

On occasion, we need to produce small runs of boards with surface-mount
parts. We do through-hole boards by hand day in and day out, but
surface-mount tech is a mystery to me, so we offload them to a local
assembly house. I don't mind paying other folks to do stuff that we
don't want to get into, like powder-coating, painting, fabbing pcbs,
etc., but it kinda rankles me to pay to have someone build up boards
just because I don't know how to do them myself.

Are there turnkey SMD assembly systems for small-volume work? I assume
we'd need a way to screen paste onto the boards, smoosh the parts on,
then flow the solder. There -- I've shown how little I understand.

There have been several discussions of this on sci.electronics.design.
It's actually quite easy for everything down to 0603s (0402s are
possible but a bit finicky) except BGA, though for FN packages you need
to modify the footprint.


You just need a fine tipped soldering iron, an ordinary one say 2mm
chisel tip, fine tweezers, desoldering braid and a flux pen. Oh, and a
little tray to put the components in. It's really as easy as through
hole when you get used to it.

Flux all the pads before soldering- best proceed one type at a time.

(1) Discretes

Put a blob of solder on one pad (best orient the board so it's the right
pad if you're rigfht- handed). Pick the component up with the tweezers,
melt the solder blob and position the component. I find it useful to try
to pick the board up with the tweezers at this point- it checks the
joint is right. When you've positioned all the components, turn the
board round and solder the other end.

(2) SOIC

Put a blob on one corner pad - I use top right. Pick up the component
with the tweezers, melt the blob and position the component. Solder the
opposite corner, then do all the other pins.

(3) Fine pitch packages including quads.

Put a blob on one corner pad. Position the component and solder that pin
down- this can take a couple of goes until you get used to it. Then
solder down all the corners. Don't worry if pads get bridged a little.
Then using the ordinary iron, clean the tip and put a little solder on
it. Draw the tip gently across the pins with a smooth action. Finally
clean up with desoldering braid- don't be too heavy or you'll lift the pads.

(4) FN packages.

Make a hole in the underside pad big enough to insert a fine soldering
iron tip. Solder the component down as for SOIC or fine pitch (finicky
as the pins don't rprotrude much) then solder the bottom down via the
hole in the underside pad.

Nearly everything I design these days uses fine- pitch SM, and the guys
who build it for me hand- assembl;e using these techniques, with success
rate approaching 100%.

Paul Burke

 

[Chuck Harris]

Mike Rocket J Squirrel wrote:

This is not a CAD question, my apologies to those with limited bandwidth.

On occasion, we need to produce small runs of boards with surface-mount
parts. We do through-hole boards by hand day in and day out, but
surface-mount tech is a mystery to me, so we offload them to a local
assembly house. I don't mind paying other folks to do stuff that we
don't want to get into, like powder-coating, painting, fabbing pcbs,
etc., but it kinda rankles me to pay to have someone build up boards
just because I don't know how to do them myself.

Are there turnkey SMD assembly systems for small-volume work? I assume
we'd need a way to screen paste onto the boards, smoosh the parts on,
then flow the solder. There -- I've shown how little I understand.

-- mike elliott

Hi Mike,

Yes, and no. The fully automated SMD assembly systems are too expensive
to ever amortize with small runs. But for runs of 100, or so boards, you
can achieve better efficiencies manually assembling SMT boards than you can
achieve with through hole.

Go to http://www.aoyue.com/en/ArticleShow.asp?ArticleID=331 and look at the 853A,
quartz infrared preheating system. It can be used, in conjunction with a hot
air rework station such as the 2738 as a small production assembly unit.

The basic sequence of events is to apply paste to the board where the parts
are to go, and manually place the parts using a microscope, or a Mantis
viewer. Put the board on the preheater, and set the temperature to slightly
above the melting point of the solder paste alloy. Watch the process
under the scope until the solder has reflowed on all joints. If one or two
are not flowing (usually due to having a lot of heat sink area on the part,
connectors are the worst offenders...), apply a little hot air with the hot
air rework station.

It is much easier than thru hole because you don't have to prepare the parts
in any way, and you don't have to clip leads, ...

I import Aoyue equipment, mostly for my own use, but I do a limited amount
of reselling, to make the equipment available at a reasonable cost to small
companies, and hobbyists.

-Chuck Harris

 

[Spehro Pefhany]

On Fri, 21 Jul 2006 15:17:57 +0100, the renowned Paul Burke
<paul@scazon.com> wrote:

Mike Rocket J Squirrel wrote:
This is not a CAD question, my apologies to those with limited bandwidth.

On occasion, we need to produce small runs of boards with surface-mount
parts. We do through-hole boards by hand day in and day out, but
surface-mount tech is a mystery to me, so we offload them to a local
assembly house. I don't mind paying other folks to do stuff that we
don't want to get into, like powder-coating, painting, fabbing pcbs,
etc., but it kinda rankles me to pay to have someone build up boards
just because I don't know how to do them myself.

Are there turnkey SMD assembly systems for small-volume work? I assume
we'd need a way to screen paste onto the boards, smoosh the parts on,
then flow the solder. There -- I've shown how little I understand.


There have been several discussions of this on sci.electronics.design.
It's actually quite easy for everything down to 0603s (0402s are
possible but a bit finicky) except BGA, though for FN packages you need
to modify the footprint.

There are some interesting new (cheap) systems for doing BGAs too.


Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com

 

[Paul Burke]

Spehro Pefhany wrote:

There are some interesting new (cheap) systems for doing BGAs too.

Well, c'mon...

 

[Hal Murray]

You just need a fine tipped soldering iron, an ordinary one say 2mm
chisel tip, fine tweezers, desoldering braid and a flux pen. Oh, and a
little tray to put the components in. It's really as easy as through
hole when you get used to it.

You also need good eyes. I use one of the head mounted magnifying
glass things, half to make things bigger and half to let me focus
closer.

--
The suespammers.org mail server is located in California. So are all my
other mailboxes. Please do not send unsolicited bulk e-mail or unsolicited
commercial e-mail to my suespammers.org address or any of my other addresses.
These are my opinions, not necessarily my employer's. I hate spam.

 

[Brad Velander]

The problem with BGAs, is that there is no cheap manner to adequately
inspect them. Even the cheaper optical devices are pricey and suffer from
significant limitations.

--
Sincerely,
Brad Velander.

"Spehro Pefhany" <speffSNIP@interlogDOTyou.knowwhat> wrote in message
news:6aq1c29ghr870ob2fq1ung4923qk5g4ns6@4ax.com...

On Fri, 21 Jul 2006 15:17:57 +0100, the renowned Paul Burke

There are some interesting new (cheap) systems for doing BGAs too.


Best regards,
Spehro Pefhany

 

[Mike Rocket J Squirrel]

Thanks to all who replied!

-- mike elliott

 

Mike Rocket J Squirrel <j.michael.elliott@gollygmail.com> wrote:

This is not a CAD question, my apologies to those with limited bandwidth.

On occasion, we need to produce small runs of boards with surface-mount
parts. We do through-hole boards by hand day in and day out, but
surface-mount tech is a mystery to me, so we offload them to a local
assembly house. I don't mind paying other folks to do stuff that we
don't want to get into, like powder-coating, painting, fabbing pcbs,
etc., but it kinda rankles me to pay to have someone build up boards
just because I don't know how to do them myself.

Are there turnkey SMD assembly systems for small-volume work? I assume
we'd need a way to screen paste onto the boards, smoosh the parts on,
then flow the solder. There -- I've shown how little I understand.

Could possible be done with a pick and place robot. Ie first apply small dots
of resin. And then place components. Before reflow.
Catch is precision I guess with 0.5 mm pitch..

 

[Anton Erasmus]

On Fri, 21 Jul 2006 15:17:57 +0100, Paul Burke <paul@scazon.com>
wrote:

Mike Rocket J Squirrel wrote:
This is not a CAD question, my apologies to those with limited bandwidth.

On occasion, we need to produce small runs of boards with surface-mount
parts. We do through-hole boards by hand day in and day out, but
surface-mount tech is a mystery to me, so we offload them to a local
assembly house. I don't mind paying other folks to do stuff that we
don't want to get into, like powder-coating, painting, fabbing pcbs,
etc., but it kinda rankles me to pay to have someone build up boards
just because I don't know how to do them myself.

Are there turnkey SMD assembly systems for small-volume work? I assume
we'd need a way to screen paste onto the boards, smoosh the parts on,
then flow the solder. There -- I've shown how little I understand.

[Snipped]

You just need a fine tipped soldering iron, an ordinary one say 2mm
chisel tip, fine tweezers, desoldering braid and a flux pen. Oh, and a
little tray to put the components in. It's really as easy as through
hole when you get used to it.

[Snipped]

I find a "Hoof" tip works much better for SMT devices with many pins.
SOIC, TQFP and others. One positions the device as described and
solder two pins to keep it in place. Apply some flux, and then with
the "hoof" tip full of solder, solder all pins on one side in one
sweep. Surface tention and the shape of the tip prevents shorts. If
you do end up with a few, it is easy to clean up with Solder wick.
With this method it takes under a minute to hand solder a 208 pin TQFP
device. One must have PCBs with soldermask though for this method to
work.

Regards
Anton Erasmus