[sdiy] pros and cons of SMT in DIY (was: Re: New Oakley Flanger/Chorus module)

[Tom Farrand]

"Magnet wire" might very well be wire-wrap wire.  This repair technique is
common and often uses a Loctite-brand 444 "Tak Pak".  That bit of kit
incorporates a gel CA glue and a rapid evaporating chemical accelerant.
One end of a repair wire is soldered where needed.  The wire is routed
along an appropriate path and is tacked every 40-50mm or so.  Wherever a
"corner" is made in the routing, a tack is also placed at each corner
(usually).  When the wire reaches its final destination it is stripped and
soldered at the proper termination point.  The accelerant speeds up the
gluing time to a few seconds each ... complete repairs are made quickly.

There are other similar solutions available for immobilizing added
conductors.  These repairs are generally quite rugged if the PCB is cleaned
of contaminants before tacking the wire down.  The better the board is
cleaned the better adhesion of the CA.

This kind of repair is suitable for industrial use ... we use it all the
time and I am unaware of any such repair having failed if applied
competently.  YMMV.

Tom Farrand






On Fri, May 19, 2017 at 8:06 PM, cheater00 cheater00 <cheater00 at gmail.com>
wrote:

> Magnet wire is mechanically fragile and does not survive long unless you
> leave the device completely alone. It's fine for testing or debugging but
> that's all. IMO not good for a piece of musical equipment that gets played
> or even... moved.
>
> On Wed, 17 May 2017 20:20 matt holland, <matt at mattholland.org> wrote:
>
>> if i understand you right, new traces on an smd board is not a problem.
>> just get yourself some thin gauge magnet wire and use a little hot glue for
>> strain relief. i do it at work all the time when boards need rework or when
>> wiring out little pin header test point jigs.
>>
>> On Mon, May 15, 2017 at 2:19 PM, cheater00 cheater00 <cheater00 at gmail.com
>> > wrote:
>>
>>> If you want to keep the same circuit topology (traces), smd is fine. If
>>> you want new traces, smd is a world of pain, and th is perfectly fine due
>>> to structural integrity that can hold a daughter pcb.
>>>
>>> On Sun, 14 May 2017 20:08 Michael Zacherl, <sdiy-mz01 at blauwurf.info>
>>> wrote:
>>>
>>>> Hi Roman,
>>>> changed the subject ...
>>>>
>>>> On 14.May 2017, at 19:35 , Roman <modular at go2.pl> wrote:
>>>>
>>>> > I dare to disagree, SMD alows for better piggybacking IMHO. It's so
>>>> easy to piggyback any passive component, just hold it on top and heat one
>>>> side, solder from the bottom one will be enough to hold it in place, so now
>>>> you can easily do the other side both hands. That's very useful in
>>>> development, and you actually can't tell at first glance there is something
>>>> added on top.
>>>> > I've done 3-layer piggybacking in 0402 sometimes.
>>>>
>>>> I can see your point and I’m afraid I wasn’t specific enough in my
>>>> posting:
>>>> I virtually (still) have no SMDs around in my drawers, so it’s through
>>>> hole components I’m talking about. And the 1/4W resistors and film caps are
>>>> quite recognisable when glued on.
>>>> But it’s doable, mostly.
>>>>
>>>> > Dnia 13 maja 2017 21:51 Michael Zacherl <sdiy-mz01 at blauwurf.info>
>>>> napisał(a):
>>>> >
>>>> > The only thing I found harder with SMT is to modify existing designs.
>>>> Leads from through hole components better allow piggybacking parts IMHO.
>>>> But that shouldn’t be a reason not to go SMT.
>>>>
>>>> --
>>>> http://mz.klingt.org
>>>>
>>>>
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