High parts count

[composition4]

Hi all,

I'm looking at doing a small production run of a stompbox I've designed, however the parts count is over 300. I know this is ridiculously high, however I've economised the circuit as much as I can. I'm planning on avoiding SMD and keeping it mostly through-hole - the enclosure will be large enough, but just wondering if there's many effects with such a high parts count that don't use SMD, and if I should just give in and go SMD?

[thetragichero]

the heck is it, if you don't mind me asking? that's s lot of parts

[composition4]

A 3 channel preamp, most of the count is resistors and caps really... I've tried to economise the circuit as mentioned by sharing sections of the signal path for all 3 channels, etc, but just by nature of how the design works I believe I'm stuck around the 300 mark. Just after feedback on whether people think its practical with through-hole components given the parts count and if there's any other examples of high parts count stompboxes that come to mind.

Thanks
Jonathan

[stallik]

How many knobs and switches does it have? This will inform the size of the faceplate and give an idea of room available in the enclosure.
What will your customers expect or prefer regarding the final size?
Are you intending to build these yourself or farm the job out?

[composition4]

Thanks for the reply - space shouldn't be an issue as the enclosure is fairly big, and it has about 30 controls in total from knobs to switches. I'm positive I can cram the PCB in if I lay it out well enough, and I'm intending to build myself (outsourcing PCB manufacture but not populating).

I just don't know if it would be a bigger issue for me to hand-solder 300 components per stompbox or to invest in sorting out a setup which will allow me to go to SMD, hence asking if anyone has any experience in building such a high parts-count design on any scale!

[ElectricDruid]

If you're intending to populate the boards yourself, then 300 parts is going to make your final product expensive just because of the time it will take you.

If you were to go SMD, I'd recommend getting the boards populated too. Since the board would be smaller, it'll likely be cheaper, and your time will only be spent on final assembly which will be much cheaper.

I've never put together something with that many parts commercially, but I spoke to the brains behind the Monowave synth, and they told me that after putting together a run of 25 of those, they never wanted to see a soldering iron again!

[composition4]

Hmmm I was thinking a run of 50 to start off and see how it is received... I'm no mathematician but I believe that's almost double 25...

Even if I can only solder up a couple per night after my day-job I guess it's not too bad in the short term, and if it's well received and I do another/bigger run I can look into outsourcing populating the board or SMD.  What's the going rate for someone to populate a board, and how would I even find where to get someone to do it reliably?

[FiveseveN]

Yeah you're not going to hand-solder 600 SMD components per night for a month. I'd say you'd need a reflow oven for this kind of production at home. Might be a good project/investment in the long run.
One of the main points of SMD is that they can be easily populated by machines. Hell, some people even made their own pick&place bots. EEVBlog had a few videos on getting your electronics manufactured but I don't have a playlist on hand.

[vigilante397]

Hello, your friendly neighborhood SMD advocate here

I do SMD for everything because it makes things easy. I have a $200 reflow oven so I pay an extra $8 or so when I get my boards to get a stencil included, then I stencil on the paste and put the components on by hand, then pop them in the oven. This is a reasonable process for me as I am not a commercial outfit and I do small volume production (usually 1 or 2 boards at a time). 300 components is a lot, I think my most complicated board was only 100 or so. Doing one of those placing components by hand wouldn't be terrible, but if you're planning to do a run of 50, that's getting into the point at which you should look at PCB assembly services, or pick-and-place machines as mentioned before.

Hope this helps

[amptramp]

The only disadvantage with SMD is if you flex the board, joints may overstress and parts may pop off or develop breaks in the solder joint that may become faults later.  If you do SMD, make the board thick and well-supported with enough standoffs to keep flex to a minimum.

[MaxPower]

So, any takers on a 700 parts (give or take) synthesizer?

[vigilante397]

So, any takers on a 700 parts (give or take) synthesizer?

Are you looking for someone to design a board, or are you selling boards? If it's the latter I may be into it. If it's the former I may still be into it

[Scruffie]

I've done a lot of PCB populating (probably 100 component circuit boards takes me 2 hours total with all the IC's etc. at a rough guess) and I'd say soldering is the easy bit, stuffing is the time consuming part.

If it's 300 - 10k resistors, it'll be boring but you could do it, if it's 300 different values, you'll go nuts in an hour, especially when you realise you're 3 short of one value and 3 plus of another after 3 hours work and have to trace through 300 components to see where you went wrong.

[samhay]

Hmmm I was thinking a run of 50 to start off and see how it is received...

Is there a market for this? 50 seems optimistic for what must be a rather niche, and expensive effect.

[composition4]

Pretty sure there's a market, and whilst what I have is fairly different to anything else out there, it's not niche. 50 seems like a fair starting point to me, I'm happy to throw a bit of money (and a lot of my time over the past couple of years) at it... Worth the risk I think.

I reserve the right to change my mind after stuffing and soldering 50 X 300 components.

[MaxPower]

So, any takers on a 700 parts (give or take) synthesizer?

Are you looking for someone to design a board, or are you selling boards? If it's the latter I may be into it. If it's the former I may still be into it

Oh no, I meant if anyone was interested in building one. It's a project recently featured in Practical Electronics (formerly Everyday Practical Electronics). Analog and midi capable if I remember correctly.

Not so bad broken down into separate sections I guess but still pretty intimidating to me. I'll stick to mucking about with the CMOS CD series and 555s for now.

[samhay]

Pretty sure there's a market, and whilst what I have is fairly different to anything else out there, it's not niche. 50 seems like a fair starting point to me, I'm happy to throw a bit of money (and a lot of my time over the past couple of years) at it... Worth the risk I think.

I reserve the right to change my mind after stuffing and soldering 50 X 300 components.

Ok, fair enough. Good luck.

[Sooner Boomer]

I've had to make fifty copies (surface mount and thru-hole) of an instrument carried on a weather balloon.  They all had to be *perfect* because once you let go of the lanyard, that balloon is NOT coming back!

My way of getting through all  fifty, then trouble-shooting, fixing, and certifying each piece, was to do a set amount each day.  For example, I would set the task of soldering 10 resistors and capacitors on every board.  And a similar task the next day.  And so on.

How an ant eats an elephant; one bite at a time.

[bartimaeus]

Don't chase bliss pedals have hundreds of smd parts on stacked pcbs?

I'd recommend smd for this many parts. Many of the same factories that manufacture pcbs also offer population/assembly, so you could even email them advance and ask about the cost of population for the number of parts you have. Alternatively, you could get a stencil from the same factory when you get your pcbs and use solder paste. You'll still need to place each part, but with a hot plate or a hot air gun it will speed things up a bit compared to hand soldering each one.

[quad4]

I assume you've dismissed using SIP or DIP resistor arrays/networks to reduce parts count?  Capacitor arrays.  Limited values are available in this format.

Definitely makes trace layout harder and wonder if they would increase noise.