PCB Assembly Costs - Page 1
Forum section: electronics / projects

author: XaviPacheco
author_rank: Regular Contributor
timestamp: July 16, 2018, 05:49:47 pm
content: Hello,I'm working on a first PCB prototype for personal use. I don't plan to make much of them for that reason. Does any of you deal with PCB assembly companies? I mean, do you usually assemble the boards by your own, or let a company make it for you? I requested an assembly quotation in a Chinese company and the unit prices of components are higher than the supplier prices, i.e, mouser or digikey. So the total assembly cost (when they assemble a minimum of 5 sets) is insanely expensive. They say that they purchase from their components factory, which is more reliable and the goods are high quality. When they purchase, the shipping cost and Customs tax will be a little high. So the unit price will be a little high.I intend to assemble through hole components by myself, and SMD components by the company.I would like to hear your viewpoints.

author: ajb
author_rank: Super Contributor
timestamp: July 16, 2018, 09:36:21 pm
content: For one or two boards the cost of contract assembly is only worthwhile if the board is not practical to assemble by hand. With only a few boards the cost of setup, machine programming, DFM review, part sourcing, and general overhead will significantly overshadow the BOM cost in most cases. On a larger job those costs get spread out more, so the piece price drops accordingly.How many components are we talking and what sort of packages? Anything 0603/TSSOP and up is doable without magnification if you have reasonably good eyesight. You can even get away without a stencil if necessary (though you will definitely need solder wick).Smaller than that and you start really wanting a stencil and a microscope--a proper stereo microscope is preferred, but a $30 USB one will usually get the job done too. There are people who assemble BGAs by hand, but those are obviously more difficult than you'd want to start with.(FWIW, personally I'd rather assemble SMT by hand than through-hole, it's much easier and faster once you get the hang of it)

author: XaviPacheco
author_rank: Regular Contributor
timestamp: July 16, 2018, 09:45:17 pm
content: Actually, the only package that worries me is this onehttps://www.mouser.com/datasheet/2/196/Infineon-TLI4970-D050T4-DS-v01_01-EN-1227870.pdfThe others I can assembly them by hand. They are usually SOIC-8, 0805 and 0603.

author: KL27x
author_rank: Super Contributor
timestamp: July 16, 2018, 09:57:20 pm
content: Take cost of quote and compare it to the cost of a hot air station and a microscope, a half dozen extra of these $6.00 chips and bare boards, plus 10 hours of setup and learning how to do this yourself.This is 0.8mm pitch, which is quite small. But IME, you don't need paste or stencil to do things like this unless it's a huge heatsink board. It's actually easier to flux, tin with an iron, flux again, pin the chip over the tinned pads with tweezers, and hit with hot air. The more flux the better. Too much solder isn't a bad thing, either. Just push the chip down with tweezers and the excess solder will squeeze out. Either into little beads or onto w/e pads overhang the chip outline.If you have this connected to big plane/pour, then it gets more expensive. You probably have to oven reflow or buy a preheater that will heat it from the bottom while you shoot the hot air from the top.Stencil pasting a footprint like this is not easy. It's a pain in the rear even when you know how to do it, correctly. It takes a lot of time and work and cleanup. It might not be worth it. But if you can do it with a $30.00 hot air gun and regular solder and flux, then it might be worth a shot.

author: Lord of nothing
author_rank: Super Contributor
timestamp: July 16, 2018, 10:28:39 pm
content: I will buy some Model Trains wo come with crappy Light for the Car.I will light every single Compartment by an LED who can turn off and on remote.For that I need an some PCB. What coult that cost?

author: ajb
author_rank: Super Contributor
timestamp: July 17, 2018, 12:37:19 am
content: Quote from: XaviPacheco on July 16, 2018, 09:45:17 pmThat's totally hand assembly territory. Even that leadless package shouldn't be too bad.My personal preference for most leadless packages, if I'm not stencilling them, is to use a soldering iron to pillow the pads, then apply paste flux and reflow. I find it's easier to get the right amount of solder that way, as long as you're careful with the amount of solder on the thermal pad, if present. This technique also works well for rework, where it may bot be possible to place a stencil.Generally, though, if there are more than a handful of fine pitch parts, I prefer a metal stencil.

author: b_force
author_rank: Super Contributor
timestamp: July 17, 2018, 11:31:36 am
content: Quote from: ajb on July 17, 2018, 12:37:19 amI don't see why that would be hand assembly territory?I have used weirder shaped packages in the past.What I do recommend is shipping your own parts to the assembly company.Especially the critical components.It's not the first you will get dodgy fake parts otherwise.I have ordered quantities as low as 100pcs.

author: XaviPacheco
author_rank: Regular Contributor
timestamp: July 17, 2018, 12:09:03 pm
content: I always buy my parts at Mouser or Digikey. And, if they are fake or not, I don't know. But they always seem to be good quality and do the job.

author: Gibson486
author_rank: Frequent Contributor
timestamp: July 17, 2018, 01:29:14 pm
content: It is not going to be cheap. You may be able to get it "cheap" if you use PCBway or something, but I am talking in relative terms. Another try would be smallbatchassembly.com, but again, it is still gonna cost at least $250 per board (labor only). However, they hand place stuff as well. The only other place that i have found is twistedtraces.com. They have a coop assembly process that supposedly really cuts down cost, but every time I try to use it, they give me a quote for regular assembly (probably because I email them from my company email).You are not only paying for labor, but you are paying for a stencil as well and they do not get their stencils from OSHstencil. If you do find a place that does it cheap, make sure they accept tubes in their machine, otherwise, you will needs to make your parts machine ready (ie order more parts than you need).

author: Gibson486
author_rank: Frequent Contributor
timestamp: July 17, 2018, 01:40:34 pm
content: Quote from: XaviPacheco on July 16, 2018, 09:45:17 pmThat should not be too bad. I will give you a tip (aside from getting a thin tip)....make the solder pads big enough so you can solder it by hand. This usually means to make them a little longer than specified on their datasheet. that way, you can just place the tip on the pad and let the heat do the work. Another possibility is to just have some one solder that one part for you. If you use PCBway, they will just solder one part, but you will wait at least 2 weeks for it. Most other assembly companies may just give you a no quote.

author: b_force
author_rank: Super Contributor
timestamp: July 17, 2018, 02:05:40 pm
content: Quote from: Gibson486 on July 17, 2018, 01:29:14 pm$250 a board? Nah.Most PCB services also have an assembly service these days.Just send them a quote, although a lot of times you can even use their calculator on the website.Most expensive are the tooling costs.Have a look at PCBWay for example, depending on the amount of parts somewhere around $200-400 for 100pcsSo that's around 2-4 bucks a board, With higher quantities prices go down very quickly to like less than a dollar a piece.

author: Gibson486
author_rank: Frequent Contributor
timestamp: July 17, 2018, 03:33:56 pm
content: Quote from: b_force on July 17, 2018, 02:05:40 pmWell, I did mention PCbway. I have used them. I am not really sure how they get the prices so low. My only complaint is the turn time with assembly. If they say it will take 5 days, it takes 10. PCB fab is usually not an issue though. Also, them pricing an assembly without actually seeing it worries me sometimes. I have only used them for very simple designs, which the OP may very well be doing.

author: b_force
author_rank: Super Contributor
timestamp: July 17, 2018, 03:37:40 pm
content: Quote from: Gibson486 on July 17, 2018, 03:33:56 pmPCBWay was just an example, there are many others.I personally never care about turn times and so on.For hobby projects, I just see whenever they arrive, for professional projects I mostly plan 2-4 weeks for it anyway

author: Gibson486
author_rank: Frequent Contributor
timestamp: July 17, 2018, 03:45:11 pm
content: Quote from: b_force on July 17, 2018, 03:37:40 pmThe only overseas company I have used extensively is Bilttele. They are definitely not as cheap as PCBway, though.

author: KL27x
author_rank: Super Contributor
timestamp: July 18, 2018, 02:23:11 am
content: Quote1. It only "works" on DIL parts that are easy to solder, anyway. On quads, extra long pads just means it's easier to inadvertently solder it on incorrectly, with bridges and misalignment, then you need to fix it.*2. It only works on parts with exposed sidepad, which this part does not have.3. So it's a bad hack that is almost never helpful, IME. On any part with sidepad, the standard footprint is almost always optimal for hand soldering, IMO, with just enough exposed pad to solder to and to prevent or greatly reduce inadvertent misalignment before you get "too far" (where you need to pull out the hot air to fix your mistake).*when you are soldering the part, the part is covering one end of the pads. So what is easier? Eyeballing ~1 mm of exposed pad all around, particularly on the side you're soldering in order to end up pretty much centered and straight? Or eyeballing ~10mm of exposed pad and having to turn the part and look at the sides before you go beyond the initial tack? The standard footprint gives me plenty of pad to solder the part super crooked (but still funcitonal). If I can't get solder to stick on one side, it's because the part is too misaligned. Longer pads can only create more problem.