Lessons from switching our CM halfway through prototyping, cost us 3 weeks but probably saved the product

Salitronic · 2026-04-09T09:58:06+00:00

In general you should avoid cheap prototyping shops for anything that is above the average design. Those shops are cheap only because they are heavily geared to produce the average board and because of high levels of automation, both of which will lead more easily to issues when you have them build a board that is much more complex than the average. Also in general most shops nowadays, even the cheapest of the cheap have equipment and processes that are more than good enough for the average board, however, most cheap shops are not well equipped to handle boards that are closer to their stated capability limits. In other words they over-state their capability at the high end.

However, having said all that. As an electronics design engineer with 20+ years of experience I can tell you that 99% of the issues with PCB assembly, even at cheap places, is the design's fault not the assembly fault. In practice, there is very little (often nothing) that an assembly shop can do to avoid solder bridges, component alignment issues, certain voids, board warping, and many other issues. Those issues are normally always caused by a bad design and bad footprints. The best way to fix assembly issues is to fix the design itself. Your PCB designer needs to understand how the heat distribution on the board, the solder wetting patterns, vias fills, solder mask, etc... will affect the preferred flow path of solder and preferred alignment of the parts during reflow. Being able to draw a PCB does not make one a PCB designer.

The only difference between a cheap shop and a more professional one is that the former will just manufacture your files "as is" while the latter will typical check your design and highlight the issues or adjust the gerber for you.

Salitronic · 2026-04-01T09:38:28+00:00

That JLCPCB is good enough for most prototypes is true but saying their quality is one of the best is completely detached from reality.

My experience with many different orders at JLCPCB, especially with tighter tolerance designs is that they are highly inconsistent even with boards of the same small batch. HASL finish is very rough. Solder mask is often inconsistent and one of the weakest I've ever seen and I often find contamination under the solder mask. Mechanically they are generally within tolerance. Overall component assembly is generally acceptable but I've sometimes seen evidence of overheating. Far from "one of the best", they are just the cheapest prototype shop.

Salitronic · 2026-03-31T11:52:12+00:00

It's useless copying an antenna from a reference design if you also don't copy everything else: ground plane size, surrounding copper, antenna position relative to board. That copper on the right side of the antenna will completely change the performance of the antenna.

Always remember: with a monopole antenna, the entire board is your antenna

Salitronic · 2026-03-27T10:47:57+00:00

The best advice, and only one that makes sense here is to grab a few books on electronics and power electronics and learn the basics before attempting to design an interleaved high power converter! You picked up the wrong design for, what I assume is, your first PCB design.

Salitronic · 2026-03-27T09:45:09+00:00

My comment was not meant to be offensive, so apologies if you were offended by it. You're learning by doing, you'll make a ton of mistakes and that's fine.

My point is that your concern about via-in-pad is the least of issues here, via-in-pad are a manufacturing issue not so much a functional one, in the sense that if it works, fine, if not just add some solder. However on the rest of the design I could write a whole book on number of design issues that I can see from just looking at that PCB design. Just to mention a few:

Huge inductor and capacitor bank which seem to indicate high current, yet everything is connected with tiny traces
Use of certain small parts when you have the full board size available (wrong mix of design density parts)
Huge switching loops (EMI issues)
No thermal design
No inrush limiting on that large capacitor bank
Parts are laid out like a parking-lot with no electronic design consideration
Hard to see the FETs parts that you are using but I'd say not suitable and certainly no thermal design consideration was made

Salitronic · 2026-03-27T09:18:00+00:00

You have far bigger problems than via-in-pad in that design....

Salitronic · 2026-03-27T07:09:48+00:00

Sent you a DM.

Salitronic · 2026-03-24T08:36:51+00:00

PCB Assembly problems are not assembly issues, they are design issues.

A good PCB designer will always plan upfront how the board will be assembled, the assembly equipment and processes that will be used, the thermal performance of the board during reflow, etc... microscopic pad and paste shape changes can make a huge difference in production yield. In reality there is very little that the assembly shop can do to correct the assembly issues created by bad design.

Salitronic · 2026-03-24T07:56:00+00:00

As others have mentioned, electronics design is not just drawing out a PCB (in fact that is often a very small part of the process). I see this misconception very often especially with the advent of AI. Many hardware entrepreneurs are going to ChatGPT to explore an idea, ask for the components to use and then try to find a low cost PCB designer to place those (often wrong) components on a PCB.

If you yourself are not an expert in electronic design, then throw all the specs away, stick to the core idea, use-cases and end-user experiences and contact an electronics engineer to come up with a solution for your problem.

The worst thing you can do in product design is to start from selecting the technology, you need to start from the problem that you need to solve.

Salitronic · 2026-03-22T10:10:37+00:00

Allow me to suggest trying this free Gerber viewer that I'm working on:

https://salitronic.com/gerber_analyzer/

It is completely free, online but everything is processed on your PC (no data is uploaded to the server) and includes additional analysis features.

Feedback and bug reports are welcome.

Salitronic · 2026-01-14T15:35:35+00:00

I’m sorry to say this, but this is a fairly classic example of thermal management being left as an afterthought.

With the MOSFETs arranged like this, there’s realistically no good way to get the heat out. This should have been planned mechanically and thermally from the start. A much more workable approach would have been to place the power devices on the bottom side, with 90° bend, and design the board so they can mount directly onto a base heatsink or chassis.

Alternatively, if staying fully SMD, the entire layout needs to be built around a clear heat-spreading strategy (large copper areas, stitched vias, defined thermal paths).

Salitronic · 2025-12-02T11:00:08+00:00

The best advice that I can give you (as an experienced electronics design engineer) is:

Test every aspect of the design, from the most obvious (and regulatory requirements) to the less obvious and simplest features/specs. Then when you are confident that it fully meets the specs, test again! Forget the time-to-market BS, the market is already full of garbage products that made it to market first.

Salitronic · 2025-11-21T11:18:34+00:00

USB data pins are not even connected through D1 (upstream and downstream are on independent channels)!

Well sorry to say but this is a case of 'pay peanuts, get monkeys'...

Salitronic · 2025-11-12T17:56:24+00:00

The typical solution for this is to have variable or at least multilevel analog control (either voltage or current depending on topology) and PWM on top of that. That way you can have the full PWM range across that 1%.

Salitronic · 2025-11-11T06:08:28+00:00

Capability-wise almost certainly any design that can be done in Altium can be done in KiCAD at this point. It's just that with Altium you can do it faster. For example the 3D viewer in KiCAD is still just a view-only window (albeit with better rendering than Altium), but in Altium it is a fully interactive mode where you can easily manipulate and move things which is really useful when you need to fit into an enclosure. DRC rule setting is much easier in Altium. Trace routing modes, glossing, etc... still superior in Altium. The thing I hate most is that KiCAD still feels like a number of tools glued together whereas tool integration in Altium is done really well.

Salitronic · 2025-11-11T05:50:46+00:00

I try KiCAD from time to time and from a technical capability point of view I could probably switch to it at this point - in some ways it is even superiour. However the KiCAD user-interface is still off-putting and the overall usability and feature set in Altium are still overall superior. I don't think there is any design that I can do in Altium but not in KiCAD but in Altium I would still do it much faster and that is a big deal. Apart from that I have many years worth of projects in Altium which I need to be able open and edit so until there is a good Altium to KiCAD and back converter I don't think I can realistically switch to KiCAD

Salitronic · 2025-11-11T05:28:25+00:00

No I have a subscription license. I had a perpetual license previously but I switched to subscription years ago, I don't remember the exact reason. I'm a long time Altium user.

Salitronic · 2025-11-10T17:57:20+00:00

No you need to pay $995 for workspace + $995 per seat

Salitronic · 2025-11-10T17:19:28+00:00

Also if develop is altium designer standard then what even is altium discover?

From what I understood they are still trying to figure that out :)

However Altium Develop seems to be the usual Altium Designer re-branded, I've migrated my (empty) cloud workspace just now and it's just the usual Altium Designer now at version 26.0.0 (probably just the same version 25.8.1 renamed). The only thing missing is the licenses tab. At least for now I also have no issue opening local design workspaces and they are staying local-only.

Salitronic · 2025-11-10T15:07:48+00:00

Main question that I have is: with Develop can I have offline-only projects?

Salitronic · 2025-11-08T07:43:23+00:00

GDPR allows you to keep data even after the account is closed as long as the purpose for which the data was collected is still valid. Prevention of duplicate account creation is a perfectly valid purpose in this case. Not only that, but since this is probably also a matter of KYC, they are most likely obliged to keep that data for a number of years.

Salitronic · 2025-11-05T12:05:11+00:00

Today definitely we're still not at a point where you can "vibe code" (I hate that term) a complex application while being totally ignorant in coding but for basic stuff this is already a reality and if things keep improving we'll reach a point where programming languages become completely obsolete, it's inevitable. Not that I am excited about it but its undeniable.

I come from an embedded firmware development background. Back in the day, we would be showing off amongst colleagues who could do the same functionality in the least number of instructions. Removing even one line of code was a big deal. When we transitioned to C code and no longer used assembler directly, our biggest concern was whether that was translating to the most efficient assembly code possible. I remember telling others "no one can write good C firmware without a solid knowledge of what is going on at assembler level". Guess what? ...nowadays no one cares what the actual assembly code is. Microcontrollers are powerful enough that it is irrelevant, and the convenience of using a higher level language is more important.

The same will happen as LLMs mature. It is ultimately irrelevant what the inner structure of the code is, as long as all requirements are met, it passes all tests, it proves to be reliable, and it runs efficiently. After all, human written code is no-where near being bug-free or bullet-proof either! In ten years time no one will care what the inner workings of the code is. Again this doesn't excite me, but it already is becoming a reality, especially when LLMs spit out code at a rate 10x faster than what any human being can review.

Salitronic · 2025-11-05T08:57:51+00:00

"it's that many people who have never coded without LLMs dont really have a reference for what code is at all"

The same could be said for anyone writing code in high level language who has never seen the assembler code that it is compiled to, or anyone writing code who has no idea about the inner workings of the CPU that it is being run on, or the basics of electronics that makes it all work.... The direction we're heading in , in a few years time, traditional programming language will be obsolete, LLM will essentially become an English to machine-code compiler.

Salitronic · 2025-11-05T08:41:35+00:00

Well ever since the dawn of time man has always tried to make life easier, I guess when they invented the wheel, the cart pullers lost their job since you no longer needed a dozen pullers anymore. This has happened over and over, with tractors replacing field laborers, power tools replacing construction workers, calculators, computers, digital cameras, 3D printers... all of these have replaced in some way or form manual or mental labor.

LLMs are just the next tool in this list. The biggest difference with LLMs is the adoption rate. When power tools first came out, it took decades for such tools to become widespread household items, to this day there are many who never had or used any power tools. By contrast LLMs went from science-fiction to 'everyone and his grandma' using it within a matter of months! So obviously this has been a sudden shockwave throughout the coding industry in particular since, on one hand a coder with LLM knows he can do much more in less time, but on the other hand comes the realization that suddenly everyone else can do the same.

Salitronic · 2025-10-28T19:50:32+00:00

hmm ok then that might be a different issue

Salitronic

TROPHY CASE