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SMD -- keeping it simple

Started by mkr5000 June 17, 2016
I don't do elaborate boards with uncommon parts and pitch etc etc.

The capacitor and resistor thing is easy enough and I'm going with 0805 for those (because of small reel sizes for one).

For a common 1n series rectifier 4001, 4002 etc I have a choice of melf, mini melf, sod 80,110,123 and 323 in my software.

Which is best for something readily available and lowest cost?

Also, of the IC choices I have it looks like either SOIC or SOP are the ones I should go with but which?

Again, for common parts -- I use optocouplers, some pic parts, nothing fancy.

I'm asking because I'm about ready to scream at the digi key catalog.

-- thanks again

On 06/17/2016 04:53 PM, mkr5000 wrote:
> I don't do elaborate boards with uncommon parts and pitch etc etc. > > The capacitor and resistor thing is easy enough and I'm going with 0805 for those (because of small reel sizes for one). > > For a common 1n series rectifier 4001, 4002 etc I have a choice of melf, mini melf, sod 80,110,123 and 323 in my software. > > Which is best for something readily available and lowest cost? > > Also, of the IC choices I have it looks like either SOIC or SOP are the ones I should go with but which? > > Again, for common parts -- I use optocouplers, some pic parts, nothing fancy. > > I'm asking because I'm about ready to scream at the digi key catalog. > > -- thanks again >
If you hand solder, the cylindrical parts have a tendency to roll away...
On Fri, 17 Jun 2016 07:53:18 -0700 (PDT), mkr5000 <mikerbgr@gmail.com>
wrote:

>I don't do elaborate boards with uncommon parts and pitch etc etc. > >The capacitor and resistor thing is easy enough and I'm going with 0805 for those (because of small reel sizes for one). > >For a common 1n series rectifier 4001, 4002 etc I have a choice of melf, mini melf, sod 80,110,123 and 323 in my software. > >Which is best for something readily available and lowest cost? > >Also, of the IC choices I have it looks like either SOIC or SOP are the ones I should go with but which? > >Again, for common parts -- I use optocouplers, some pic parts, nothing fancy. > >I'm asking because I'm about ready to scream at the digi key catalog. > >-- thanks again
MELFs are a nuisance. SOD323 is convenient, small but not too small, but won't dissipate much power. The SMB size is good for diodes that will get warm; add some copper pours to improve heat transfer. SOT23 opamps and mosfets are nice. Use SO8 amps if you have tons of room; they run cooler and are easier to probe than smaller stuff. 0805 is a nice size for resistors and caps when density permits. -- John Larkin Highland Technology, Inc lunatic fringe electronics
On Friday, June 17, 2016 at 10:53:23 AM UTC-4, mkr5000 wrote:
> I don't do elaborate boards with uncommon parts and pitch etc etc. > > The capacitor and resistor thing is easy enough and I'm going with 0805 for those (because of small reel sizes for one). > > For a common 1n series rectifier 4001, 4002 etc I have a choice of melf, mini melf, sod 80,110,123 and 323 in my software. > > Which is best for something readily available and lowest cost? > > Also, of the IC choices I have it looks like either SOIC or SOP are the ones I should go with but which? > > Again, for common parts -- I use optocouplers, some pic parts, nothing fancy. > > I'm asking because I'm about ready to scream at the digi key catalog. > > -- thanks again
Why are you using the digikey catalog? (do they still make those?) Their website has a nice search engine. George H.
I meant search but not much help on this size thing.

So John -- use SO for the IC's ? Yes, I do have plenty of room.

-- thanks   this makes it easy.

0805, SOD323 and SO ?  
mkr5000 <mikerbgr@gmail.com> writes:
> Also, of the IC choices I have it looks like either SOIC or SOP are > the ones I should go with but which?
My usual advice for SMD parts: If you're hand-soldering them, change the footprints to have the pads extend a few mm away from the part. This gives you an easy way to "drag" excess solder away from the pins, so you can fix bridges.
On Fri, 17 Jun 2016 10:50:57 -0700 (PDT), mkr5000 <mikerbgr@gmail.com>
wrote:

>I meant search but not much help on this size thing. > >So John -- use SO for the IC's ? Yes, I do have plenty of room. > >-- thanks this makes it easy. > >0805, SOD323 and SO ?
That would be easy to assemble and probe. We have a mixed stock of resistors, 1206 and 0805 and 0603 and a few oddballs. When I design a board and need, say, a 3.24K resistor, I might have to pick an 0603, because it's in stock, even though the board is mostly 0805. We should have planned better, I guess. -- John Larkin Highland Technology, Inc picosecond timing precision measurement jlarkin att highlandtechnology dott com http://www.highlandtechnology.com
On Friday, June 17, 2016 at 2:51:38 PM UTC-4, DJ Delorie wrote:
> mkr5000 <mikerbgr@gmail.com> writes: > > Also, of the IC choices I have it looks like either SOIC or SOP are > > the ones I should go with but which? > > My usual advice for SMD parts: If you're hand-soldering them, change the > footprints to have the pads extend a few mm away from the part. This > gives you an easy way to "drag" excess solder away from the pins, so you > can fix bridges.
Yeah and it gives you a landing spot for the iron tip and solder... (I use the thinnest grade rosin core solder for smd parts.) The bigger the part the better IMO. Sometimes there is no room. George H.
On Fri, 17 Jun 2016 11:51:51 -0700, John Larkin
<jjlarkin@highlandtechnology.com> wrote:

>On Fri, 17 Jun 2016 10:50:57 -0700 (PDT), mkr5000 <mikerbgr@gmail.com> >wrote: > >>I meant search but not much help on this size thing. >> >>So John -- use SO for the IC's ? Yes, I do have plenty of room. >> >>-- thanks this makes it easy. >> >>0805, SOD323 and SO ? > >That would be easy to assemble and probe. > >We have a mixed stock of resistors, 1206 and 0805 and 0603 and a few >oddballs. When I design a board and need, say, a 3.24K resistor, I >might have to pick an 0603, because it's in stock, even though the >board is mostly 0805. We should have planned better, I guess.
I just pick the part I want and even the manufacturer (most are in there). They're all stocked. I personally keep (sometimes short) reels of Panasonic (ERJ2RKF) 1% 0402 resistors for my prototypes. They're what Digikey carries. ;-)
On 17/06/2016 16:27, John Larkin wrote:
> On Fri, 17 Jun 2016 07:53:18 -0700 (PDT), mkr5000 <mikerbgr@gmail.com> > wrote: > >> I don't do elaborate boards with uncommon parts and pitch etc etc. >> >> The capacitor and resistor thing is easy enough and I'm going with 0805 for those (because of small reel sizes for one). >> >> For a common 1n series rectifier 4001, 4002 etc I have a choice of melf, mini melf, sod 80,110,123 and 323 in my software. >> >> Which is best for something readily available and lowest cost? >> >> Also, of the IC choices I have it looks like either SOIC or SOP are the ones I should go with but which? >> >> Again, for common parts -- I use optocouplers, some pic parts, nothing fancy. >> >> I'm asking because I'm about ready to scream at the digi key catalog. >> >> -- thanks again > > MELFs are a nuisance. SOD323 is convenient, small but not too small, > but won't dissipate much power. The SMB size is good for diodes that > will get warm; add some copper pours to improve heat transfer. > > SOT23 opamps and mosfets are nice. Use SO8 amps if you have tons of > room; they run cooler and are easier to probe than smaller stuff. > > 0805 is a nice size for resistors and caps when density permits.
I've tended to standardise on 0603, being of sufficient size to be handled, and was the cheaper[1] style for most Rs and Cs. [1] It was some time ago but found 0805s were generally more expensive. -- Mike Perkins Video Solutions Ltd www.videosolutions.ltd.uk