EEVblog2: When you REALLY don't want to pay for a Double Sided PCB - Page 1
Forum section: electronics / general

author: golden_labels
author_rank: Super Contributor
timestamp: March 01, 2025, 07:12:19 pm
content: I can understand, why the designer goes for a single-layer board. But could anybody explain to me, why did they go forfourdifferent models of a 0Ω link?

author: coppercone2
author_rank: Super Contributor
timestamp: March 01, 2025, 07:33:14 pm
content: Hmm so you don't need to flip it over or take it out of the chassis to fix it, nice. Instead of a 16 layer cluster fuckin case it went over your head though, which it likely did for cost crazed developers, this is likely NOT a reliable solution because it has so many unnecessary bonds compared to a copper monolithI think its OK when its a few jumper wires because it means your almost there. What you are seeing in that video is a psycho ass cost solution.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 01, 2025, 08:00:08 pm
content: The layout does not look very intelligent - probably should have got away with less than half the jumpers. Maybe they want it to look complicated.They may want the physical size for a mechanical reason - though it does not really look that way. Otherwise 1/3 the size and double sided could well be cheaper.

author: Bud
author_rank: Super Contributor
timestamp: March 01, 2025, 08:29:04 pm
content: The cost of pic-n-place machine time, solder paste , jumpers, and the job setup and quality control was less than cost of a double-side PCB ?

author: coppice
author_rank: Super Contributor
timestamp: March 01, 2025, 08:31:24 pm
content: You see things like that in a lot of white goods - things like washing machines. They'll do almost anything to stick with phenolic boards.

author: golden_labels
author_rank: Super Contributor
timestamp: March 01, 2025, 10:08:43 pm
content: Neither sticking to FR-2 boards, nor trying to avoid the cost of multi-layer board explains a design, which requires four different rolls of 0 Ω links in the pick-and-place machine. This would increase the cost.I may rationalize the need for two: inductance or current capacity considerations. But four?

author: nctnico
author_rank: Super Contributor
timestamp: March 02, 2025, 12:21:13 am
content: Quote from: coppice on March 01, 2025, 08:31:24 pmI can imagine that having vias might be considered bad due to corrision by water / moisture in white goods and conformal coating costs more than having a single sided board. Then again I agree the layout of this board doesn't look very intelligent and the number of jumpers is very extreme. OTOH, I have seen boards in old TVs with lots of wire jumpers as well.

author: wraper
author_rank: Unknown
timestamp: March 02, 2025, 12:38:00 am
content: What a fucking lazy layout. They substituted layout optimization with the amount of jumpers. No way this board needs this many. It would need 1/5th at most, and more like 1/10th if layout was done properly. This stupid board has like 5 jumpers per single LED or button which are basically the only functional things besides the IC that drives them.

author: langwadt
author_rank: Super Contributor
timestamp: March 02, 2025, 12:39:19 am
content: Quote from: Bud on March 01, 2025, 08:29:04 pmmaybe completely skipping the drilling and plating steps does make the board much cheaper, but yeh it is hard to imagine how the cost of jumpers/solder/errors doesn't cost more that you save

author: Smokey
author_rank: Super Contributor
timestamp: March 02, 2025, 12:56:08 am
content: I've seen through hole boards with TONS of jumper link wires before. This kind of thing..https://i.sstatic.net/twMh0.jpg

author: themadhippy
author_rank: Super Contributor
timestamp: March 02, 2025, 01:17:27 am
content: Quoteyep,to the uninitiated wow look at all the chips in this thing it must be good

author: schmitt trigger
author_rank: Super Contributor
timestamp: March 02, 2025, 02:16:26 am
content: If I am going to take a wild guess… perhaps the company had purchased a gazillion 0 ohm jumpers that became excess inventory. Thus someone descended from the corporate headquarters and with a firm voice commanded: USE THEM!

author: Smokey
author_rank: Super Contributor
timestamp: March 02, 2025, 02:26:56 am
content: Quote from: schmitt trigger on March 02, 2025, 02:16:26 amLets say $0.03 per component placement for assembly cost... That's an extra $3 for 100 components on the board. .. per board...A full reel of 5000 0805 0Ohm jumpers is only $16https://www.digikey.com/en/products/detail/stackpole-electronics-inc/RMCF0805ZT0R00/1756901plus if you find yourself with extra inventory, that's what parts brokers are for

author: Jay_Diddy_B
author_rank: Super Contributor
timestamp: March 02, 2025, 04:35:29 am
content: Hi,This is an audio product. Those are not 0resistors.Those are low-distortion, super-conducting audio interconnects. The  are extra super-conducting, the [ 0 ] are merely super-conducting. The elaborate pattern is patent pending super flux cancellation.Jay_Diddy_B

author: sleemanj
author_rank: Super Contributor
timestamp: March 02, 2025, 04:40:42 am
content: Quote from: Smokey on March 02, 2025, 02:26:56 amEven JLC is only 0.0017 per SMT joint for the standard assembly process.I wouldn't be surprised if their amortised cost was 1/10th that including the resistor for this board.

author: coppercone2
author_rank: Super Contributor
timestamp: March 02, 2025, 04:46:26 am
content: Does anyone else feel like this is the reason you wished you went into accounting instead of engineering? When someone thinks that white good PCB manufacturing costs and quality are reasonable goals for 'engineering prototypes' and low scale production? Like when your developing something for a particle accelerator or chemical plant and you get asked why are you making this so expensivereal life engineering : the same questions that this topic starter is asking are asked about quantity : 5/year . I already can't wait for the christmas pizza party

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 02, 2025, 10:36:52 am
content: Quote from: coppice on March 01, 2025, 08:31:24 pmYes that's still common in many devices. Even switching power supplies.

author: Whales
author_rank: Super Contributor
timestamp: March 02, 2025, 10:53:53 am
content: I think this is awesome. I hope the guy who designed it had fun. Maybe they had an edict from above? Better to make the most of it and have fun than to do it begrudgingly.

author: jnk0le
author_rank: Regular Contributor
timestamp: March 02, 2025, 11:45:59 am
content: Wouldn't it be a kind of a design that prevents 1:1 chinese copies?BTW, what is part number of that qfn chip?

author: coppice
author_rank: Super Contributor
timestamp: March 02, 2025, 06:48:33 pm
content: Quote from: SiliconWizard on March 02, 2025, 10:36:52 amIn SMPSes its more common to have a main phenolic board full of chunky through hole parts, and a little FR4 daughter board with surface mount controller circuitry.

author: rsjsouza
author_rank: Super Contributor
timestamp: March 02, 2025, 07:34:38 pm
content: I have been doing some FR-1 single layer designs lately and I also can't understand how this can offset an extra layer of copper. Sure, 0Ω resistors are dirt cheap and dual layer usually allows designers to place parts on both sides (which increases assembly costs), but certainly this seems to make sense for those million+ production runs.

author: golden_labels
author_rank: Super Contributor
timestamp: March 02, 2025, 08:36:21 pm
content: Ok, a next guess.What I can get from a 1080p video is of quality not good enough for effortless reverse engineering. But even a rudimentary analysis suggests it makes no sense. Lines doing unneeded loops around other traces. The entire left side seems to be a tangled mess of jumps serving no purpose, given the other end’s position is unconstrained.Could it be a major auto-router fail? Perhaps one of those newfangled smortnet routers? Maybe originally solved for a 2-layer board and then manually corrected with links?Though this still doesn’t explain using four different 0 Ω link types.Quote from: jnk0le on March 02, 2025, 11:45:59 amI was thinking about a scrambling attempt too. It’s not an effective method of hiding information, but either the designer or the ordering party could be unaware of that. It’s not hard to imagine a situation: a smart person offers to naïve businessperson a “PCB nobody can copy.” A pretty common scam.

author: wraper
author_rank: Unknown
timestamp: March 02, 2025, 10:04:45 pm
content: ^I have a feeling someone just wanted to prank their employer or cause monetary damage while technically doing their job.

author: tszaboo
author_rank: Super Contributor
timestamp: March 02, 2025, 11:46:34 pm
content: Quote from: Smokey on March 02, 2025, 02:26:56 amAnd that's digikey pricing. I remember seeing a purchase order for millions of 100nF capacitors and it was 7 EUR per reel. So if we work with these prices, that 50 odd component is about 10 cents. When you own the assembler, and you produce it in two shifts, then your production line can do anywhere in the range of a thousand boards a day, and the SMT line is never the bottleneck, it's the human operators.So yes, single sided will be cheaper.For this board, something doesn't make sense. Almost as if they had some sort of diode encoding for the keys to be able to detect them separately, and then someone replaced those diodes with 0 ohm resistors. Loosing the ability to decode multiple keypresses at the same time.

author: wraper
author_rank: Unknown
timestamp: March 03, 2025, 12:03:56 am
content: Quote from: tszaboo on March 02, 2025, 11:46:34 pmDon't forget these mostly are 1206 and assembly cost. Not to say barely any of these jumpers are actually needed, it's simply a ridiculous design. I think you can get away with <5 jumpers if actually bothered to make a nice layout. There are barely any parts on this board beside jumpers. Looks like April Fools' that actually got into production.

author: tszaboo
author_rank: Super Contributor
timestamp: March 03, 2025, 03:29:06 pm
content: Quote from: wraper on March 03, 2025, 12:03:56 amWhen you sell hundreds of thousands of board a year, you have your own pick and place machine.Often times it's dedicated to just one product. And often times it's not the bottleneck, that's going to be the manual steps. Human takt times of 30 seconds mean that you can assemble ~200.000 boards in one year in one shift. While a pick and place machine can be done with such a board very quickly. Then it doesn't really matter how many parts you have on the board, if the machine finishes quicker than the human, it has to wait. And you cannot set up the pick and place to do something else, because storing days worth of production is cumbersome, and changing the machine has it's own risk. I've seen it, just changing one single resistor meant that an engineer had to take apart the entire board and measure every single component by hand.I know we are not used to these numbers, but the cost calculations on a dedicated production line are very different. The cost price of the production line for this PCB could be about the same as 1 day of the sale price of the product. Then you run the same board on the same line hopefully for a few years.

author: AndyC_772
author_rank: Super Contributor
timestamp: March 03, 2025, 03:44:28 pm
content: Quote from: golden_labels on March 01, 2025, 07:12:19 pmIt's just possible that the designer was simply unqualified to do the job.I've worked with people before who were employed as engineers, but lacked fundamental understanding of how PCBs are designed and manufactured. They made odd design choices that weren't motivated by some unseen but important priority or specification - they were just plain wrong.Occasionally we see products like this - not designed by a competent engineer with unexpected priorities or outside influences, but instead, designed by someone who simply doesn't know any better. The designer in this particular case might just be someone who doesn't know what a multi layer PCB even is.

author: tszaboo
author_rank: Super Contributor
timestamp: March 03, 2025, 03:58:40 pm
content: Quote from: wraper on March 02, 2025, 10:04:45 pmActually after watching this video for the third time, maybe you are right.The reference designators for the jumpers are "JKE" with an O printed on the top of it...I've never seen JKE used for reference designators, also it's 2 character too long...

author: AndyC_772
author_rank: Super Contributor
timestamp: March 03, 2025, 05:54:38 pm
content: Jumper, Known Excessive

author: wraper
author_rank: Unknown
timestamp: March 03, 2025, 06:42:37 pm
content: Quote from: tszaboo on March 03, 2025, 03:58:40 pmNice catch, if combined with marking on a jumper you get JOKE.

author: temperance
author_rank: Super Contributor
timestamp: March 03, 2025, 07:42:15 pm
content: You can find similar constructions in hifi equipment from early 2000's. I had for example a mini disk player and the complete control board consisting of 3 or 4 large TQFP's, some smaller chips,...all on a single layer board with 0R SMD jumpers on the bottom side and wire links as regular trough hole. The AD/DA board and the remaining control interface was also assembled onto FR-1 board with a mixture of SMD and trough hole components.Let's say you have a piece of equipment with one or two large boards and e few smaller ones. That's what you typically see in consumer equipment. A small PCB for the power switch, on other one for the incoming mains and fuses, an other one for the front panel controls,...If you do this with FR4, you need equipment to cut the panel into small pieces unless you used milling to separate the boards. With FR1 you can just snap the boards into pieces by hand and the required cut outs are punched. In TV's and the like you often find pieces of FR1 used as spacers, cable retainers,... all broken of from the same panel.I can imagine wave soldering being faster than reflow soldering and you don't need to maintain stencils and control a paste printer which will act up sooner or later. But I have no idea about the number of solder defects for reflow versus wave soldering SMD components.But maybe the truth is very different. Those unknown to us Japanese CAD systems with libraries with DIL packages which for the PCB as well as the schematic can't do double sided boards yetThey are working on that.

author: Smokey
author_rank: Super Contributor
timestamp: March 03, 2025, 07:46:58 pm
content: Back from the cave man etch-your-own-boards days, I remember doing single sided layouts is actually often harder and requires more layout skills to make it all work than multi-layer boards (it's significantly easier to drop a via to an inner layer and/or put some parts on the bottom).If this was a joke, someone spent quite some time laying out out the joke.

author: wraper
author_rank: Unknown
timestamp: March 03, 2025, 07:52:33 pm
content: Quote from: Smokey on March 03, 2025, 07:46:58 pmNot a problem when you are paid by the hour.

author: wraper
author_rank: Unknown
timestamp: March 03, 2025, 10:24:17 pm
content: Does anyone see some pattern? Maybe if rotated? I have a small suspicion different jumper type placement might be not random.

author: nctnico
author_rank: Super Contributor
timestamp: March 03, 2025, 10:32:00 pm
content: I don't see any pattern. If anyone does, please enlighten usBut I hope it is not like playing songs in reverse and claiming to hear the devil speaking.Dave definitely has stumbled upon something interesting.

author: Whales
author_rank: Super Contributor
timestamp: March 05, 2025, 01:46:23 am
content: Maybe they have multiple 0-ohm feeders in their PnP as a time optimisation, and it just so happens they have a mix of reels.

author: ballsystemlord
author_rank: Frequent Contributor
timestamp: March 05, 2025, 02:45:09 am
content: That's a great trouble shooting video, Dave. I didn't guess the trace at any point in time. Thumbs up for sure.I think that instead of a jumper wire, you should have used a 1206 0ohm resistor for consistency.Thanks for the cool video!

author: elektryk
author_rank: Regular Contributor
timestamp: March 05, 2025, 12:19:52 pm
content: Quote from: jnk0le on March 02, 2025, 11:45:59 am"Code obfuscation" in hardware world...

author: Langdon
author_rank: Frequent Contributor
timestamp: March 05, 2025, 01:44:03 pm
content: Quote from: golden_labels on March 01, 2025, 07:12:19 pmStrangely enough, that's pretty common.I've seen PCBs with 4 dfferent kinds of 0 ohm resistors.I will post pictures and description if I still have them (I might have alrady taken them to the scrap yard).

author: thm_w
author_rank: Super Contributor
timestamp: March 05, 2025, 10:35:38 pm
content: Using JLC prices:- 10c of parts (0 ohms)- 42c for assembly (0.3c per part, about 140 parts)- 43c per PCB (assuming the size is 10x12cm)JLC doesn't charge any less for 1-layer PCB, so no way to estimate that.Based on JLC prices, its cheaper to go with a 2 layer board and eliminate that ~52c in parts and assembly.Quote from: Whales on March 05, 2025, 01:46:23 amExactly, the P&P could have 4 or 8 heads. So having multiple reels keeps all of the heads going instead of only running one at a time, probably twice as fast if not more.

author: Sensorcat
author_rank: Regular Contributor
timestamp: March 06, 2025, 12:22:40 am
content: Thank you for this really interesting repair video! For me, the lesson learned is that optical inspection of PCBs can't be overestimated. Why? Because many repair attempts suffer from lack of documentation, while reverse-engineering requires excessive time. But without any insight into the design, it would have been possible in principle to find this. Also, it could be wise to clean any PCB that is dirty while doing the optical inspection. I know, I know, in this case, the broken track was very hard to spot, but given the sheer number of failure modes that alter the look of a PCB, I will put even more emphasis on optical inspection in the future.Regarding the odd design, I would like to add this to the explanation guesswork: There could have been a change in the design, late in the project, and an attempt was made to change as little as possible, because the project/product manager said so. For instance, it is conceivable that the original design had less switches or LEDs. Then, 2 days before HW design freeze, the designer was told to add switches. No time for optimization, only pseudo-optimization. Or there is a series of similar products, and this design is a valid cost minimization of the whole product range.

author: Langdon
author_rank: Frequent Contributor
timestamp: March 06, 2025, 01:15:46 am
content: Quote from: golden_labels on March 01, 2025, 07:12:19 pmI assume the four different models are rated for different current.In theory, it's irrelevent, but in reality, a 0Ω resistor is acually more like 0.0001Ω or something.

author: EEVblog
author_rank: Unknown
timestamp: March 06, 2025, 01:26:34 am
content: Quote from: langwadt on March 02, 2025, 12:39:19 amI think you'd be surprised how much cheaper, especially when you are a huge consumer company with a close direct relationship with the manufacturers

author: thm_w
author_rank: Super Contributor
timestamp: March 06, 2025, 01:29:09 am
content: Quote from: Langdon on March 06, 2025, 01:15:46 amNothing in this circuit would be anywhere near the current rating of a 0805 or 1206 0 ohm resistor.The official ratings for some cheap panasonics are, 0805/1206 = 2A (4A peak). But they generally won't blow up until you hit ~10A peaks.

author: wraper
author_rank: Unknown
timestamp: March 06, 2025, 01:43:48 am
content: Quote from: thm_w on March 05, 2025, 10:35:38 pmCost is irrelevant because almost none of those jumpers are actually needed. The only purpose they serve is to create spaghetti monster. It's like how many jumpers do you need to connect a dozen of LEDs and a few switches?

author: thm_w
author_rank: Super Contributor
timestamp: March 06, 2025, 10:12:47 pm
content: Quote from: wraper on March 06, 2025, 01:43:48 amUnless you have proof this board can be easily done with 0 jumpers, I'd want a realistic number of parts to compare cost to. 20 jumpers? 40?We also need someone to give the cost of a single layer board in this size. Google says its going to be 20-30c per board, but real data would be nice.

author: wraper
author_rank: Unknown
timestamp: March 06, 2025, 10:21:50 pm
content: Quote from: thm_w on March 06, 2025, 10:12:47 pmLike <5. And if MCU firmware/pinout are optimized for PCB routing, probably none at all because switches and a few other SMT parts can be routed underneath. When I was still etching PCBs myself I routed more complicated boards with no jumpers at all.

author: coppercone2
author_rank: Super Contributor
timestamp: March 06, 2025, 10:34:14 pm
content: And its just a bad decision because everyone of those parts can tomb stone, have a cracked solder joint, delaminate, etc.

author: thm_w
author_rank: Super Contributor
timestamp: March 06, 2025, 11:50:12 pm
content: Found 51pc sold of these boards on aliexpress, so its a common failure mode:https://www.aliexpress.us/item/3256805458779154.htmlTwo boards:- 40-HPB350-KEI1G the on in this thread with the crazy jumpers- 40-HPB350-KYI1G this one seems to have a reasonable number of jumper links, but no micro, so less connectionsMade and probably designed by Daysun:https://www.daysun.net.cn/en/index.aspxIt looks too good to be autorouted, but the jumpers may be some kind of automated addition in their layout software. Since they make a lot of these type of designs.You can start to see the logic: most of their button/LED boards are single sided, so they could have decided that from the start, told layout dude what to do, without thinking it through. Layout dude isn't going to risk criticizing bosses decisions.

author: tom66
author_rank: Super Contributor
timestamp: March 09, 2025, 10:55:24 pm
content: Quote from: golden_labels on March 01, 2025, 07:12:19 pmI have seen this happen - though not quite on such a bad scale as this - when designs are merged and copied across from other projects. We ended up with a board with 0201, 0402 and 0603 decoupling caps. All were eventually rationalised to 0201 common parts. It can also happen when an engineer manually enters in part details rather than using a part management system, or mistakenly selects multiple types of the same value, and then they end up with different parts on the BOM. It should be caught in the BOM review stage, but if they mark them differently "JUMPER 1206", "0 OHM 1206", "0 OHM RES 3216M", "0 OHM JUMPER 5% TOL" etc. etc. And if there's pressure to get a product out in time for e.g. Xmas sales period, then things get missed like this.Quote from: AndyC_772 on March 03, 2025, 03:44:28 pmOr, they were told by management it 'had to be single layer' to save costs because that's how they've always done it, and in some cases, that is an appropriate way to control costs. But they didn't appreciate their field enough to go, "hang on, this doesn't make any sense." Or they didn't feel senior enough to speak up. Happens a lot! We practice a policy where I work where every decision by the most senior member of the team can be critiqued, it helps avoids bad decisions like this.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 10, 2025, 08:40:29 am
content: Having the PCB single sided makes sense. What does not make much sense is having 2 seprate PCBs directly side by side and having so many 0 ohm jumpers. Even without alloing for pin swaps and related software adjustments it should not take much more than 1 jumper per LED+switch.Even if done in steps to replace older versions or include other variants it makes little sense - there is not much difference in designing the slightly larger (if needed at all) to include the odd adapert PCB that is in between.For the number of jumpers it looks like a true beginner doing a bad job or bored layout person trying to get the most jumpers on a PCB. Handling the jumpers in the PCB software may not be the most efficient way - it may not be high priority in the software.

author: rsjsouza
author_rank: Super Contributor
timestamp: March 12, 2025, 11:45:22 am
content: Quote from: golden_labels on March 01, 2025, 07:12:19 pmIn one of my last designs I had not much board space and needed to use different sizes of zero ohm resistors whenever I needed to jumper over many tracks at once. Having several 0603 (one per jumpered track) was very space consuming, since a 1206 can jump up to four 0.2mm tracks with 0.2mm track-to-track and track-to-pad clearance (I couldn't use thinner tracks on my design).

author: Eagcress88
author_rank: Contributor
timestamp: April 08, 2025, 10:24:15 am
content: Quote from: temperance on March 03, 2025, 07:42:15 pmI agree that FR1 was super practical for mass production! Snapping boards by hand saved time and cost in consumer electronics back then!

author: 5U4GB
author_rank: Super Contributor
timestamp: April 09, 2025, 12:10:50 pm
content: Quote from: golden_labels on March 01, 2025, 10:08:43 pmWell, they went with 0 ohms where possible but had to use a few 000's for higher precision.