I'd be interested in comments on practical experience with mechanical
alignment of 5mm through-hole LEDs with and without "stoppers".

Far away from here, where I can't get involved directly, and with at
least one layer between me and the people doing the work, 20k x 6 =3D
120k 5mm LEDs are about to get assembled into 20k PCBs.
I can within reason stipulate what procedures are used but information
chain is slow and cumbersome so understanding options helps speed
things up.

_______________

LEDs are to be wave soldered. LEDs may be being machine or hand
inserted. Leads may be being trimmed and bent before soldering, or
just trimmed, or ... .

The LEDs have "stoppers", small protrusions on the leads which
position them about 10mm above the PCB surface when correctly
installed.

A recent small batch of assembled LEDs that I saw samples of had some
at unacceptable angles to the vertical wrt horizontal PCB. It was
claimed that this was caused by bending after manufacture but
inspection indicates that LEDs were misaligned during soldering. Lead
cinching during assembly and prior to soldering MAY allow LEDs to be
correctly aligned depending on tightness of cinch etc.

LED leads are 0.5mm square so a 0.7mm hole is acceptable but close to minim=
um.

LEDs inserted into holes may "rock" from side to side on stoppers.
Maximum rock angle depends on hole diameter. 0.7mm (sensible minimum)
limits rock to a modest angle. Say 10 - 15 degrees max.

Manufacturer wants to slot board so LEDs sit hard on board and
stoppers are bypassed. I am very resistant to this suggestion as slot
for leads 9about 1.2mm x 0.6mm for 0.5mm square lead) not only is an
invitation to disaster soldering wise, but allows so much mechanical
slop that LED alignment is still not guaranteed.

Questions

1:  Presumably a typical pick and place machine that can handle 5mm
LEDs will also cut and cinch LED leads well enough for them to be
aligned when using stoppers. Yes?

2. How common is pick and place capability for 5mm LED package?

3: I'd assume that LEDs wave soldered without cinching would be a
disaster whether using stoppers or sitting LEDs on PCB.
    I'd assume that solder wave would tend to push LEDs up and also
tilt them at an angle as the wave passed. Also that some flotation may
occur.
    Yes?

3.  If LEDs were hand inserted prior to wave soldering I'd assume that
use of a manual cut and cinch tool would be a minimum in order to
stabilise LEDs from wave soldering process.
Yes?

Based entirely on circumstantial information it appears that the
manufacturer MAY be using manual insert, trim without cinch, wave
solder.
If so I'd like to change that to include either auto insert with cut
and bend or manual cut and bend.

Any other thoughts welcome.




      Russell
--=20
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