Ask HN: How to improve PCB prototyping iteration time?

Most of the comments strongly advise against moving to Shenzhen.

Having prototyped in both places I’ll make some arguments for. I’ll preface it’s only worth it if you’re beyond the limits of what American facilities can do and it's a step function in workflow and getting setup. There is an acceptable cultural tunnel vision in our field that developed in the 1980s for "how to do things" and hasn't changed much beyond "4 layer pcb on FR4 with surface mount components" - going against that grain requires an interdisciplinary mindset - as in "make a functioning circuit on a piece of toast" level of creativity[1].

If you’re building wearable tech there’s a strong chance you’ll need to make flex pcbs sooner or later. Those are comically cheap in China and stupid expensive stateside.

Especially when you start pushing the boundaries - there’s so much low hanging fruit for experimenting with your PCBs when you’re in the factory making them. Most US manufacturers will only let you use one color for a solder mask. In Shenzhen we pioneered using full RGB to print any graphic on your pcb back in 2017. Even on top of the chips themselves. It’s now pretty easy to source. This is literally just by being on the factory floor and saying “hey can you do step 5 before you do step 4? - we want to take the boards to this other factory across town first” And they say “sure”. Likewise if you want to mount your parts sideways or upside down to save space. Or say, take a literal sea shell through a copper PVD machine and mill away some traces and mount some chips. They do not care and will gladly take your money and make it happen.

One time we couldn’t find a single vendor in the US or Europe who would embed chips in the middle of pcb layers[2]. This was a weekend project for one of our Chinese vendors - who also had never done this but it sounded like fun so she said “no problem”.

Can get turnaround on prototype boards with assembly for free once you have a cm or just $50 if you don’t. One American vendor comically insisted one couldn’t mix flex and rigid boards for one of our designs for less than $10k. In China it cost me $80. Likewise we mounted chips to non-traditional media like credit cards with no sweat.

Any chip we wanted was available through HQB or TaoBao when Digikey was still backed up on Covid.

Test fixtures (the laser cut jigs that you program and test pcbs) are $100. Stateside they were half as useful and $2000.

You’re one blue Buick minivan ride from Guanzhou where all the garments in the world are made. Being at the intersection of these two cities is a strategic advantage.

Cost of living is cheap.

It will make you a better engineer by exposing you to the dirty business of manufacturing first hand. I'll go so bombastically hyperbolic and say not moving to Shenzhen as an EE is like not moving to Nashville as an aspiring country musician.

In China the saying goes “anything is possible, nothing is easy.” I’d mostly agree with this but also point out that price is completely-orthogonal-to-possible in China, absolutely not in the US, and straight up forbidden in Germany.

[1] https://talk.dallasmakerspace.org/t/breadboard-electronics/1...

[2] https://twitter.com/pmg/status/1248148053795540992/photo/1

p.s. If you enjoyed this comment, you may also enjoy my "So you want to start a factory?" reply on a post from a few days ago [3]

[3] https://news.ycombinator.com/item?id=40001222

floxy · a year ago

>you’ll need to make flex pcbs sooner or later. Those are comically cheap in China and stupid expensive stateside.

OSH Park does flex:

https://docs.oshpark.com/services/flex/

paulgerhardt · a year ago

No purple, no stiffeners, 12+ day turn, 4mil thickness(!), but yes I understand one can wait and get boards more cheaply from OSH or shipped from China. I’m more trying to address the “hey let’s go to the factory this weekend and try something never before done” kind of use case which they don’t do.

TaylorAlexander · a year ago

I really want to develop a product in Shenzhen some time. During the height of covid lockdowns in China I got a little concerned about personal safety as a possible visitor. But I also know millions of foreigners visit every year and our news distorts everything coming from China. Do you ever have concerns about personal safety or unexpected government action there?

paulgerhardt · a year ago

My threat model is probably not yours and my threat model in China is not my thread model in the US is not my threat model in South Africa. But if I had to pick one point, I'd say most people I've met who haven't worked in China over-index on political risk and under-index on driving risk.

For some data, in 2019 about 3 million Americans went to China and the number detained for political reasons (and not working for the US government or journalism) was probably in the single digits?

In the US I've driven about 600,000 miles and been in one traffic accident. In China I've ridden about 30,000 miles and been in 6 traffic accidents.

Plenty of other things people have gone on at length about things that are just different risks in both places.

HeyLaughingBoy · a year ago

It occurs to me that this is the kind of question that /u/SexyCyborg would probably have a good answer for if she hadn't been forced to get off Twitter by her local Chinese police. I think she had an account here, maybe she's still around?

I miss Naomi's tweets!

RohKo · a year ago

Banger. Confirmed my suspicions about flex PCBs and the viability of European manufacturing (unviable). Being able to shoot to Gaungzhou would also be useful. I've got a couple more questions - I'll dm you on twitter.

wferrell · a year ago

Thank you for this great post.

This is exactly what prototype PCB manufacturers are for. If you're in the Bay area, SF Circuits (and a dozen others) will give you 24h/48h turnaround times. This is a highly commoditized service. Even the generic manufacturers like PCBway have options you can purchase for faster turnaround if you meet the constraints.

Don't move to Shenzhen. You don't have the social connections for that and it'd just give you a bunch of new problems.

the__alchemist · a year ago

I am guessing, based on previous research into similar services, that this costs 20x more and doesn't do assembly. Is this accurate?

AlotOfReading · a year ago

Some do assembly, some don't. Depends on the house and each one will have slightly different constraints on what they'll assemble. As for costs, it balances out with the costs of slower iteration. When EEs don't have fast turnaround (or too short schedules) they start loading all their little experiments onto the iterations they do have and you can end up with bloated BOMs, overspecified parts, and "good enough".

michaelt · a year ago

Right, but JLCPCB pricing is like $5 for 5 boards. Maybe less. So paying 20x as much is still only $100.

You don't get many engineer hours for $100.

RohKo · a year ago

Lol that's defo true - I'm driven to this thought as lead times are super frustrating!

AlotOfReading · a year ago

You mention in another comment that you're London based. PCBTrain is probably a better suggestion for that locale [0].

[0] https://www.pcbtrain.co.uk/

stingrae · a year ago

Sure but it comes at a huge cost penalty.

mrbungie · a year ago

Moving to Shenzen also comes with cost penalties of many kinds. Bigger penalties than just shelling out more money to local companies.

DHaldane · a year ago

Without knowing exactly what you are working on, here are a few ideas:

1. Figure out if you can do fewer slow iterations. What's driving the need for a full PCBA run for each iteration? Might be able to split out to rigid assembly and flex for example.

2. Run more experiments in parallel. If you have multiple ideas or variations to test, design them all and fabricate them all. Flex antenna? Make like 30 parametric variations.

If design then becomes the bottleneck, then automate that next.

krasin · a year ago

I would like to give this response a signal boost, based on the fact that the comment author knows a lot about PCB design, prototyping and manufacturing.

Gotcha - thanks for the advice. The IC performance on the flex circuit is a key part of the product so will figure out how to test that in a lofi manner.

gravescale · a year ago

Maybe you only need a small bit on the flex (main CPU and the DDR to prove signal integrity?), and the rest can just go on an ugly quick PCB for software validation and bringup. Stuff it with test points, current shunt points, larger parts for easy probing, add some mounting holes too fasten it to a test rig, whatever.

Then just glomp the flex down to the test PCB with some nice Samtec connectors (you can enough free samples for a small batch of test units even) or an edge connector on the stiffener.

quanto · a year ago

There are many good common sense answers in this thread: parallelize the runs, use faster (but more expensive) local runs, have a better model (physical or digital) to reduce the runs.

To answer your specific question, Shenzhen is a good place to work on hardware, but it is not like you just fly in, and people start building for you. Your own lead time (establishing yourself there) will likely be in weeks if not months. This is from my personal experience in Shenzhen and other hardware founders'.

If you want to build the prototype faster, identifying the bottleneck is a great start. Which takes most time? For up to medium complexity, PCB fab (the board itself) is the most time-consuming part. Anything more complex, it could be the SMT assembly. Each part of the entire process can be optimized: PCB fab can be done in-house quick (chemical etching, CNC machining, etc). Assembly can be optimized too (solder reflow oven, solder paste stencils, etc) on a small scale. I would estimate a batch of 5 boards of 50 SMT components each can be produced under 8 active engineer-hours. That's your entire prototype in a work day.

Do you have professional/academic training in electrical engineering? EE is no less complex than CS, and perhaps studying up the entire process will help you identify what's possible and what's the bottleneck.

> 5 boards of 50 SMT components each can be produced under 8 active engineer-hours

Far less! That's about how many boards of similar complexity I could hand-stuff and reflow in an hour!

junon · a year ago

Don't assemble via JLC. Get a good soldering iron, skillet, sand, paste, and order from mouser to do them yourself. If you're iterating errata with a full run each time you are wasting unbelievable amounts of both time and money, and you're probably not tinkering with the board enough, increasing your overall iteration count.

I assembled my own PCBs for years and once I used JLC assembly I never went back. It costs more in shipping from Digikey to pay for assembly at JLC, so you’re literally not saving money. You’re also spending more time ordering parts, and the actual assembly is a pain even if you’re skilled. Hand placing components just sucks. Plus you end up with boxes of capacitors and resistors you will never use again.

I just don’t think this really is a better way of doing things.

Do you generally limit yourself to the parts that JLC stocks? Or do you send them reels with the parts you want to use? Or will they order the parts you want? Last I looked, I don't see that they have any Microchip microcontrollers available (plus plenty of other active components and connectors).

4b11b4 · a year ago

JLC is too cheap now to do this yourself.

OP is complaining about turnaround times for development, not cost.

Also, really take a look at JLC's component prices and compare them. Some of their markup, namely for ICs, is borderline criminal.

buescher · a year ago

You’re confounding lead times on assembly services with iteration time.

If you’re bootstrapping, find a good quick turn board house and assemble the boards yourself. Get an lga-12 stencil and hot air tools, maybe a benchtop reflow oven.

talldayo · a year ago

> Strongly considering moving to Shenzen to build the prototype.

That seems like a profoundly personal decision that would have more ramifications than you expect.

Breadboarding should be possible, same with soldering together prototype PCBs as long as you're not concerned with wearing the prototype yourself. There's also (albeit expensive) circuit modelling/validation software you could try to use. I don't think many circuit designers have a workflow where they perpetually buy finished prototypes to check if they're working or not, though.

Interesting I see. I'm moving from breadboarding to PCBs because I'm using ICs which are way too small to solder by hand and I've already prototyped with their off-the-shelf dev board versions.

xargon7 · a year ago

Consider ordering reusable chunks of your circuit as PCBs instead of iterating on entire boards. You can connect the chunks with breadboards or connectors or something.

jon-wood · a year ago

How small is "too small" here? I'm by no means an expert at soldering but with some patience I can hand solder down to 0603 components, and I know people who can go much smaller than that (right down to the sort of thing where if you sneeze finding the components you just scattered around is like finding a specific grain of sand on the floor). You can get practice boards for next to nothing online if you don't want to risk damaging high value components.

mikeInAlaska · a year ago

It's just faster and easier to iterate PCBs anymore than large breadboard creations.

abetusk · a year ago

Fiber laser. Even a 20W fiber laser will ablate copper. 30W-50W are now avaiable for under $2k, maybe even dropping still.

You'll be limited to single or double sided, without vias but considering its rapid prototyping, these are the compromises to be had.

You could always try CNCing prototypes but this is fraught with trouble. Fiber lasers offer the simplicity, repeatability and speed that normal laser cuters, but with metal.

[0] https://www.youtube.com/watch?v=PoYcjyghDx4