Homebrew PCBs

I've just made a PCB which uses a Mega8 AVR in the LQFP package. I don't tin 
my boards, and usually solder the leads of that sort of chip one at a time 
after fluxing the pads with a flux pen. This time I thought I'd try 
drag-soldering, although I wasn't sure how well it would work without any 
solder mask. Instead of the flux pen I used Warton Future HF Rework Jelly on 
each row of leads after tacking down two opposite corners of the chip. With 
a Metcal hoof tip (larger than the mini-hoof I use for fine-pitch devices) I 
drag-soldered each row, and only had one bridge. The Rework Jelly is more 
active than the flux in the pen, and I got very neat joints - much better 
than I can achieve by soldering the leads one at a time.

Leon
--
Leon Heller, G1HSM
Suzuki SV1000S motorcycle
leon.heller@...
http://www.geocities.com/leon_heller

Problem is once you get the hang of it you are just going to hate
mounting SMT caps and resistors because you can do a 40-80 pin IC
faster than a couple of SMT resistors or caps

Don't discount the 'toater oven' method of reflow where you can mount
and solder all your SMT devices in one shot .... One caveat though, I
haven't tried it on an unmasked board so I can't say how it works in
that situation

JR

--- In Homebrew_PCBs@yahoogroups.com, "Leon Heller" <leon.heller@...>
wrote:
>
> I've just made a PCB which uses a Mega8 AVR in the LQFP package. I
don't tin 
> my boards, and usually solder the leads of that sort of chip one at
a time 
> after fluxing the pads with a flux pen. This time I thought I'd try 
> drag-soldering, although I wasn't sure how well it would work
without any 
> solder mask. Instead of the flux pen I used Warton Future HF Rework
Jelly on 
> each row of leads after tacking down two opposite corners of the
chip. With 
> a Metcal hoof tip (larger than the mini-hoof I use for fine-pitch
devices) I 
> drag-soldered each row, and only had one bridge. The Rework Jelly is
more 
> active than the flux in the pen, and I got very neat joints - much
better 

> than I can achieve by soldering the leads one at a time.
> 
> Leon
> --
> Leon Heller, G1HSM
> Suzuki SV1000S motorcycle
> leon.heller@...
> http://www.geocities.com/leon_heller
>

From a former collegue who has wide experience from components and testing of the same, I got a warning on soldering ceramic SMD caps. Never poke the soldering iron on the cap as this will cause micro-cracks that later will let humidity into the cap and at a later instant (the most critical of course) the cap will go dead, explode or start to conduct like crazy.

  ----- Original Message ----- 
  From: jr_dakota 
  To: Homebrew_PCBs@yahoogroups.com 
  Sent: Tuesday, October 10, 2006 1:17 AM
  Subject: [Homebrew_PCBs] Re: Surface-mount soldering


  Problem is once you get the hang of it you are just going to hate
  mounting SMT caps and resistors because you can do a 40-80 pin IC
  faster than a couple of SMT resistors or caps

  Don't discount the 'toater oven' method of reflow where you can mount
  and solder all your SMT devices in one shot .... One caveat though, I
  haven't tried it on an unmasked board so I can't say how it works in
  that situation

  JR

  --- In Homebrew_PCBs@yahoogroups.com, "Leon Heller" <leon.heller@...>
  wrote:
  >
  > I've just made a PCB which uses a Mega8 AVR in the LQFP package. I
  don't tin 
  > my boards, and usually solder the leads of that sort of chip one at
  a time 
  > after fluxing the pads with a flux pen. This time I thought I'd try 
  > drag-soldering, although I wasn't sure how well it would work
  without any 
  > solder mask. Instead of the flux pen I used Warton Future HF Rework
  Jelly on 
  > each row of leads after tacking down two opposite corners of the
  chip. With 
  > a Metcal hoof tip (larger than the mini-hoof I use for fine-pitch
  devices) I 
  > drag-soldered each row, and only had one bridge. The Rework Jelly is
  more 
  > active than the flux in the pen, and I got very neat joints - much
  better 
  > than I can achieve by soldering the leads one at a time.
  > 
  > Leon
  > --
  > Leon Heller, G1HSM
  > Suzuki SV1000S motorcycle
  > leon.heller@...
  > http://www.geocities.com/leon_heller
  >



   

[Non-text portions of this message have been removed]

At 4:18 pm (PDT) Mon Oct 9, 2006, jr_dakota wrote:
>[snip]
>Don't discount the 'toater oven' method of reflow where you can mount
>and solder all your SMT devices in one shot

Just a 'heads up' for our UK readers that Lidl is offering
an Electric Grill and Oven for £19.99 in its Weekly Specials
on Monday 16th October, 2006.

Details and picture:
  http://newsletter.lidl.co.uk/c/r?EMID=09500E301MHST03RE2DQ401K6KCEQ

3 heat settings - choose from upper, lower or combined heat for perfect 
cooking results.
  Temperature regulator from 100°C - 250°C. 60 minute timer. 1,380 watt.
Includes non-stick coated baking tray, 2 chrome plated grill racks and a 
pair of tongs.
Oven capacity (L): 15. Available in white or silver. Size (cm): 34.3 x 43 x 30.
3 year manufacturer's warranty. Price per item £ 19.99

Caveat emptor -I make no warranty that it is fit for SMT or any other 
purpose ;-)
but Lidl specials are usually good quality and value for money


Regards, LenW

H Len

> Just a 'heads up' for our UK readers that Lidl is offering
> an Electric Grill and Oven for \ufffd19.99 in its Weekly Specials
> on Monday 16th October, 2006.
>

Thanks for the heads up on the toaster oven. Will take a look on Monday. I
hope the offer is on here as they do vary from store to store.

Couldnt verify the offer for myself as the Lidl website is a pile of ****

Everytime I tried to view offers for the 16th Oct it asked for my postcode
which I entered. It then chucked me back to the 12th Oct and if I selected
16th it asked for my postcode again.

They dont even know where there stores are !!!!

They show two for Great Yarmouth but we only have one, the addresses given
are for the old closed one and the new replacement one but the maps for both
are wrong. The new store shows as being on the retail park that the old one
was on but in the site occupied by McDonalds. The old store shows as being
on a different retail park between the old and new stores on the site
occupied by Comet.

Dont you just love websites like that :(

Hope I can get on with SMT stuff, my eyesight is geting so bad that I need a
magnifying glass to read the numbers on ordinary DIP chips now, got some SMT
samples that are so small they look as if they just have one very wide flat
pin on each side :(

Regard

Keith

"Keith Doxey" <ukha@...> writes:

> Hope I can get on with SMT stuff, my eyesight is geting so bad that
> I need a magnifying glass to read the numbers on ordinary DIP chips
> now,

I've got a magnifying visor I use with 2.5x and 3.75x optics for it.
It's an OptiVisor, made by Donegan Optical Co in the USA.  Woodcraft
sells them.  The 2.5x is about right for most work; the 3.75x is for
the tiniest parts.

> got some SMT samples that are so small they look as if they just
> have one very wide flat pin on each side :(

I'm starting to get "old eyes" but with the visor I can still hand
solder down to 01005 caps (16 mil x 8 mil):

http://www.delorie.com/pcb/smd-challenge/proto-boards.html
http://www.delorie.com/pcb/smd-challenge/fp-pix/

Len Warner wrote:
> Just a 'heads up' for our UK readers that Lidl is offering
> an Electric Grill and Oven for \ufffd19.99 in its Weekly Specials
> on Monday 16th October, 2006.
> 
> Details and picture:
>   http://newsletter.lidl.co.uk/c/r?EMID=09500E301MHST03RE2DQ401K6KCEQ

Neat. Let's see... \ufffd20 for the oven, about the same again to build a clone of 
Elektor's temperature controller, two days of lunch breaks to port the T-con 
firmware to run on a PIC...

And about \ufffd50 for the tub of solder paste. Ouch.

> Caveat emptor -I make no warranty that it is fit for SMT or any other 
> purpose ;-)

The big questions are:
   - How fast can it heat up (no real way to speed that up other than adding 
more heating elements, or add some thermal insulation around the oven)
   - How fast can it cool down (add a fan from a fan-assisted oven to speed 
that up)
   - How hot will it go if you bypass the thermostat?
   - How long does it take to reach that temperature?

> but Lidl specials are usually good quality and value for money

Hm, I'll take your word for it.

-- 
Phil.                         |  (\_/)  This is Bunny. Copy and paste Bunny
ygroups@...         | (='.'=) into your signature to help him gain
http://www.philpem.me.uk/     | (")_(") world domination.

Another 'heads up' for our UK readers.

This time, Wilkinson ["Wilko"] is offering a toaster oven,
in its January sale - three on display in my local store.

Details below from www.wilko.co.uk, search for OVEN.

Mini Oven - Sabichi - Product ID:0228912/5
White, 9 Litre capacity
Regular price £14.99, sale £10.00.

Can be used for baking, grilling and toasting
[Looks a reflow mod candidate too :-) ]

Bimetal thermostat control from 70-220 deg C
[plus full CW 'toast' = full on? - manual claims 250]
Clockwork minutes timer with auto switch off
Removable crumb tray, baking pan and wire racking
[nice slide-out action linked to drop-front glass door]

230/120V (1200WATTS)
[silica-tube element top & bottom, dual voltage claim
makes me suspect 120V elements but I didn't notice
a voltage select switch: rating label reads 1300W]


Regards, LenW

Again for our UK readers...

Found this forum, a follow-up to the Elektor toaster-oven
controller article, which includes temperature profile
measurements on an Argos Hinari oven.

There is also mention of some success using a _toaster_
on its side (no, you don't pop-out the cooked board ;-)

http://www.elektor-electronics.co.uk/default.aspx?tabid=29&forumid=16&postid=697&view=topic

Elektor Forums > SMD Reflow Oven (January 2006)
Topic > Components in the UK? (2 pages, 32 posts)

(If link doesn't work for you, drill down from home page)

Compared to the Wilko Sabichi, the Hinari is smaller,
which may be good for its max temperature and has
its controls (timer & one-two element switch but no
thermostat) underneath rather than RHS, which might
be better if you want to make a conveyor oven.

OTOH it costs twice as much as the Wilko sale price.

Having seen the Wilko one - though only a picture of the
Argos one - I'm more attracted by the Wilko Sabichi.

If one uses triac phase control it won't matter much if
the elements turn out to be 2x120V in series and could
even allow some over-running, though a power limiting
protection circuit might be advisable.


Regards, LenW