Reference Design impee PCB Manufacturing and Assembly Recommendations


#1

I would like to build a DIY home automation system using Electric Imp and I would like to obtain a few of the imp team’s reference design hardware (Sana, Kaylee, possibly Jane and Flora).

I’m comfortable with through hole component soldering and ordering all of the parts from Digi-Key but many of the reference designs have SMT components that I don’t have the tools or experience be able to assemble with any confidence that it would actually be put together correctly when I’m done. I also have limited experience with custom PCB prototyping/manufacturing.

Does anyone have any companies they recommend for prototype (quantities of 1 or 2) PCB manufacturing and assembly? Any ideas as to how expensive this would be over the raw BOM (I don’t require any kind of rapid turn around time)?


#2

I’m working on the same thing. I’ve basically taken the April and expanded it. It will be my first board, so I wanted to start simple, and or at least with circuits that I know work. I’m using Eagle since Adafruit and Sparkfun have a lot of good libraries as well as the April schematic. I am going to have a few through hole parts, but mostly SMT. I’m hoping I can get the parts placed reasonably after the board is made. What are you using to design the board?


#3

I use dfrobot.com for all my pcb manufacturing. They are based in china and the turnaround time is excellent and you get pro quality boards in most colours.
The best part is they are cheap too. Cheaper than osh park too. I’m based in the uk so I was a bit worried the first time but so far they have been great.
Don’t be put off with smt either. With a little practice you can easily hand solder 0802 and 0602 size smt parts. Always use solder paste and get a stencil made at osh stencils. For about 70 dollars you can get a hot air reflow wand which makes smt soldering a breeze. Have a peek on eBay for an aten hot air station it’s what I use.
For a look at the quality of dr robot pcb’s search this forum for the G-imp or have a look at ingenuitymicro.com as all thier boards get made by df. Or have a look here http://www.ghielectronics.com/community/creations most of these community made boards are dfrobot too.


#4

We hand-build all our SMT boards without stencils; it’s actually not that bad.

Things that make it easier:

  • a board pre-heater. This gets the board hot from underneath, so you don’t need to add much more heat with the iron to get the solder melted. Pretty sure ours is an OKI PCT-100 from eBay, but there are likely a lot of cheaper options.
  • a hot air gun. On their own, these are not so useful (takes too long to heat things with groundplanes), but with a pre-heater they’re excellent. We have this one, but there are cheaper ones available (eg on ebay): http://www.amazon.com/X-TRONIC-MODEL-4040-Soldering-MAGNIFYING/dp/B003TC8EQS/
  • a microscope. Not really needed if you have good eyesight, but if you’re doing this a lot they’re great. Amscope have some amazing deals on these. http://www.amscope.com/lowpower-stereo-boomstand.html
  • good flux!
  • sharp point tweezers

Even for the small DFN packages like the TPS power supply, you just need to use a soldering iron to get some solder on the pads, put some flux down, pop the chip on, stick it on the preheater for a minute or two then a little hot air will see it solder itself down nicely.

For SMT discretes, just put solder on one pad, then use the tweezers and iron to solder that one leg. Now the part is not going to move, you can use solder and iron to do the other side.

Small run SMT is generally pretty expensive. You may find buying your own equipment is cheaper :slight_smile:


#5

Thanks Hugo, I’m going to take a look at that equipment. I definitely wouldn’t want to pay a lot to have SMT placed just to find out that my circuit wasn’t right. :slight_smile: As soon as I get this first board completed, I’m going to take Tom up on his offer to check things over.


#6

I’ve been doing a bunch of at-home smd soldering and I am amazed at how robust the process is - meaning easy in spite of my lack of experience. I am considering buying a pre-heater for rework (due to circuit errors mainly). For my builds, which are all builds of one or two, I have been using my hacked oven (imp-controlled).

one thing i got recently was a vacuum tweezers. I hold/pinch the vacuum hose with my left hand and run the tool with my right hand. The pencil has a hole in it that if I plug the hole the vacuum goes up - release the hole and the vacuum drops but does not completely go away. When I pinch the hose the vacuum goes to nothing and the parts fall down.

I found this to be a lot faster than the mechanical tweezers - even though I have a pretty nice one.

Hugo, thanks much for sharing the list of your tools. I’ve recently done a VQFN package with 0.5mm pitch and I had to take the borrow a microscope to check the work.


#7

@mjkuwp94 Sounds like you have some cool stuff going on. If I were to schedule a google hangout one of these nights, would you be interested in sharing? I started a Google+ community called Electric Imp Disciples, and this is the kind of information that I’m hoping to get everyone sharing. Maybe we could get Hugo to show us the Electric Imp’s board equipment.


#8

@jwehr, thanks! but time and other things would get in the way right now. I will be sharing in the ‘got imps’ when I get my next watt meter running. I found of two boards, one works and one doesn’t. To me that was a very big and lucky success and just means I need to rework the other one. I am using the same IC as the Becky board and I guess the imp team must have done theirs with the tools described above. off to shop for pre-heaters and microscopes (or put them on my Christmas list : )


#9

@Hugo I don’t suppose there are any gerbers for Becky are there?


#10

We’ve specifically not posted gerbers for Becky because it’s a socketed AC-powered device without AC isolation - ie, you don’t want to build that with an imp001 (which is what the becky uses as it was pre imp002).

The other issue is that the PSU transformer is custom wound and not available off the shelf, so it’s a bit hard to build.


#11

@deldrid1: Yes, it is difficult to assemble the SMT components at home if you don’t have the experience of these components. So, it is better to assemble it through the professionals.

I used a company called advanced assembly at work. However, you can probably have it done cheaper by overseas assemblers like bittele, goldphoenix pcb. They have sales offices in North america as well.

printed circuit board assembly china


#12

I am agree with robert that it is difficult to assemble the SMT components at home becuase I really have an experiance of doing it. So I searched for the PCB manufacturing companies who are doing that & I found this. Can anyone suggest me that should I go for it or is there any other…?
PCB manufacturing