M
mkr5000
Guest
If my boards have 1206 pads and the assembler wants to use 0805 parts, do I need to change the PCB art or will the 1206 pads be ok? Anyone run into this?
THANKS.
THANKS.
U
Uwe Bonnes
Guest
mkr5000 <mikerbgr@gmail.com> wrote:
If you design for manufacturing (DFM), use fitting pads.
--
Uwe Bonnes bon@elektron.ikp.physik.tu-darmstadt.de
Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt
--------- Tel. 06151 1623569 ------- Fax. 06151 1623305 ---------
If you design for manufacturing (DFM), use fitting pads.
--
Uwe Bonnes bon@elektron.ikp.physik.tu-darmstadt.de
Institut fuer Kernphysik Schlossgartenstrasse 9 64289 Darmstadt
--------- Tel. 06151 1623569 ------- Fax. 06151 1623305 ---------
P
Piglet
Guest
On 22/03/2020 13:25, mkr5000 wrote:
In general no it will not work but it depends on the 1206 footprint you
have used. You will have to check. I had this situation for a limited
time when the 1206 part designed-in was unavailable and we got by by
hand placing a 0805 substitute at an angle but it was not pretty.
piglet
In general no it will not work but it depends on the 1206 footprint you
have used. You will have to check. I had this situation for a limited
time when the 1206 part designed-in was unavailable and we got by by
hand placing a 0805 substitute at an angle but it was not pretty.
piglet
W
Winfield Hill
Guest
mkr5000 wrote...
I have created 1206 and 1210 footprints that include pad
extensions for 0805, allowing for assembly flexibility.
It does limit the trances running between the pads.
--
Thanks,
- Win
I have created 1206 and 1210 footprints that include pad
extensions for 0805, allowing for assembly flexibility.
It does limit the trances running between the pads.
--
Thanks,
- Win
R
Rick C
Guest
On Sunday, March 22, 2020 at 9:25:57 AM UTC-4, mkr5000 wrote:
Isn't the assembler responsible for the result?
Why does he want to make this change? Why does he care what size parts are used??? Seems odd, smaller parts have more problems with tombstoning although I don't know this is an issue with 0805 parts.
I've asked assembly houses to go in the other direction. I've had to make part changes and didn't want to change the art work putting an 0805 on 0603 pads.
Without some justification I wouldn't permit the change. I'm wondering though why you used 1206 parts when they were available in 0805 packages. Usually the engineer is trying to save board space. I guess your design is not tight.
--
Rick C.
- Get 1,000 miles of free Supercharging
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Isn't the assembler responsible for the result?
Why does he want to make this change? Why does he care what size parts are used??? Seems odd, smaller parts have more problems with tombstoning although I don't know this is an issue with 0805 parts.
I've asked assembly houses to go in the other direction. I've had to make part changes and didn't want to change the art work putting an 0805 on 0603 pads.
Without some justification I wouldn't permit the change. I'm wondering though why you used 1206 parts when they were available in 0805 packages. Usually the engineer is trying to save board space. I guess your design is not tight.
--
Rick C.
- Get 1,000 miles of free Supercharging
- Tesla referral code - https://ts.la/richard11209
L
legg
Guest
On Sun, 22 Mar 2020 06:25:50 -0700 (PDT), mkr5000 <mikerbgr@gmail.com>
wrote:
You'll get tombstoning in reflow, if you just direct sub
in the fab line.
If you're doing just s few, or doing it manually, you can
get away with it, by checking each and evry one of them.
RL
wrote:
You'll get tombstoning in reflow, if you just direct sub
in the fab line.
If you're doing just s few, or doing it manually, you can
get away with it, by checking each and evry one of them.
RL
C
Clive Arthur
Guest
On 22/03/2020 13:25, mkr5000 wrote:
time, if 0805 has sufficient power dissipation, if it's just a very
small run, if there are no tracks between 1206 pads, if changing the
artwork is a major issue, then I'd probably go for it but make sure the
boss approves in writing or audio recording.
--
Cheers
Clive
If he wants 0805 because he has stock and it will save you money and
time, if 0805 has sufficient power dissipation, if it's just a very
small run, if there are no tracks between 1206 pads, if changing the
artwork is a major issue, then I'd probably go for it but make sure the
boss approves in writing or audio recording.
--
Cheers
Clive
Guest
Piglet <erichpwagner@hotmail.com> wrote in
news:r57tij$hf9$1@dont-email.me:
Take two at half value each and stand up a tee pee for series final
value hand soldered applications. For manufacturing, not.
And yes, it still meets IPC-A-610 rev f.
Not suitable for production numbers UNLESS you REALLY trust the
soldering skills of that assembler and he or she does them all.
news:r57tij$hf9$1@dont-email.me:
Take two at half value each and stand up a tee pee for series final
value hand soldered applications. For manufacturing, not.
And yes, it still meets IPC-A-610 rev f.
Not suitable for production numbers UNLESS you REALLY trust the
soldering skills of that assembler and he or she does them all.
Guest
Clive Arthur <cliveta@nowaytoday.co.uk> wrote in news:r589e5$9im$1
@dont-email.me:
Hmmm... there is a business in that form of "signature" methinks.
@dont-email.me:
Hmmm... there is a business in that form of "signature" methinks.
Guest
Rick C <gnuarm.deletethisbit@gmail.com> wrote in
news:33e6d6c4-688f-469e-ad48-2f502b889dfc@googlegroups.com:
Stupid question. Hand assembly on SMT requires top soldering
skills. That buck stops at the person whom put said solderer in the
seat.
> Why does he want to make this change?
Obviously the 1206 part is not available. A tech or engineer might
want a change for an electrical reason, but this request is from an
assembler, asking if it is OK to put an 0805 part onto a 1206 pad is
a valid question for a proto or small number run being hand
assembled. Unless dissipation comes into it. That would be why he
asked, because he doesn't want a hot spot to occur. It depends also,
one would guess, on the pad gap the layout package used had.
See above.
Pretty sure he is talking about hand assembly and hand soldering.
If he is talking about programming a picker/placer with an undersized
part, it is a no go right out of the stencil wiper.
I got no impression he was talking about a build house. He said
"my assembler".
> Without some justification I wouldn't permit the change.
Machine assembled means no way it would fly. The answer is a
definite no.
Doubtful, but dissipation may be a factor in this scenario. Likely
a factor in the assembler asking about it.
Likely an older design, becasue we could certainly do any board
smaller with today's 0402 and 0201 stuff, so more must come into play
here than PCB real estate.
> I guess your design is not tight.
Never got the notion that he might not have the part?
Since he referenced still being in layout, he could shrink a
shitload of parts. not enough info to say.
news:33e6d6c4-688f-469e-ad48-2f502b889dfc@googlegroups.com:
Stupid question. Hand assembly on SMT requires top soldering
skills. That buck stops at the person whom put said solderer in the
seat.
> Why does he want to make this change?
Obviously the 1206 part is not available. A tech or engineer might
want a change for an electrical reason, but this request is from an
assembler, asking if it is OK to put an 0805 part onto a 1206 pad is
a valid question for a proto or small number run being hand
assembled. Unless dissipation comes into it. That would be why he
asked, because he doesn't want a hot spot to occur. It depends also,
one would guess, on the pad gap the layout package used had.
See above.
Pretty sure he is talking about hand assembly and hand soldering.
If he is talking about programming a picker/placer with an undersized
part, it is a no go right out of the stencil wiper.
I got no impression he was talking about a build house. He said
"my assembler".
> Without some justification I wouldn't permit the change.
Machine assembled means no way it would fly. The answer is a
definite no.
Doubtful, but dissipation may be a factor in this scenario. Likely
a factor in the assembler asking about it.
Likely an older design, becasue we could certainly do any board
smaller with today's 0402 and 0201 stuff, so more must come into play
here than PCB real estate.
> I guess your design is not tight.
Never got the notion that he might not have the part?
Since he referenced still being in layout, he could shrink a
shitload of parts. not enough info to say.
Guest
Winfield Hill <winfieldhill@yahoo.com> wrote in
news:r5816t0uim@drn.newsguy.com:
Isolation value reduction too (for 1206), but that doesn't matter
since one is slappin' an 0805 down anyway.
news:r5816t0uim@drn.newsguy.com:
Isolation value reduction too (for 1206), but that doesn't matter
since one is slappin' an 0805 down anyway.
J
Jasen Betts
Guest
On 2020-03-22, mkr5000 <mikerbgr@gmail.com> wrote:
well the kind of fit, but When I tried that I got some tombstones about one in 400 parts
this is probably worse with taller parts.
--
Jasen.
well the kind of fit, but When I tried that I got some tombstones about one in 400 parts
this is probably worse with taller parts.
--
Jasen.
T
Tim Williams
Guest
Same pad gap dimension according to IPC SM-782. But 782 is deprecated, so
if you're following IPC-7351B you may have pin-touching-soldermask errors.
As long as the 0805 reaches, it'll probably work. Tombstoning is rare on
such large parts.
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/
"mkr5000" <mikerbgr@gmail.com> wrote in message
news:7e939326-6319-466b-8522-9290c01b39b5@googlegroups.com...
if you're following IPC-7351B you may have pin-touching-soldermask errors.
As long as the 0805 reaches, it'll probably work. Tombstoning is rare on
such large parts.
Tim
--
Seven Transistor Labs, LLC
Electrical Engineering Consultation and Design
Website: https://www.seventransistorlabs.com/
"mkr5000" <mikerbgr@gmail.com> wrote in message
news:7e939326-6319-466b-8522-9290c01b39b5@googlegroups.com...
Guest
"Tim Williams" <tiwill@seventransistorlabs.com> wrote in
news:r5dc2o$t50$1@dont-email.me:
Strange since the term came from a time when the SMT parts were
even larger than 1206, and 0805, and certainly was viable through
that period as well. The thing is that when they are that large, the
gap is large enough for a dab of adhesive, so no tombstoning.
It definitely happens in a small contract shop where they might
choose to continue using some old paste after it has expired to save
cash.
Seeing how many parts pop in reflow usually teaches them the
reality of their attempt to save money.
news:r5dc2o$t50$1@dont-email.me:
Strange since the term came from a time when the SMT parts were
even larger than 1206, and 0805, and certainly was viable through
that period as well. The thing is that when they are that large, the
gap is large enough for a dab of adhesive, so no tombstoning.
It definitely happens in a small contract shop where they might
choose to continue using some old paste after it has expired to save
cash.
Seeing how many parts pop in reflow usually teaches them the
reality of their attempt to save money.