hybridfree/eevblog-posts huggingface dataset:
SOT23 with "WRS" marking..then "72" on its side? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: August 22, 2023, 09:35:08 am
content: Hi,Do you know what component this is?..SOT23 with "WR5" marking..then "72" on its side? "72" in smaller letters.It looks like only pins 1 and 3 are connected in.......taking 3 to be the one pin "on its own"...is it a 6v2 zener?________________________________________Also what about "Z1W" on a SOT23?...its pins 1 and 2 are connected together________________________Also "1GW" on a SOT23.......is it a BC847C?________________________Also "A6W" on a SOT23.......?... is it a BAS16?

author: Kean
author_rank: Unknown
timestamp: August 22, 2023, 10:07:17 am
content: Some possibilities, but not guaranteed... though these ones are reasonably familiar to me.WR5: BZX84-B6V2Z1W: BZX84-C4V71GW: BC847CA6W: BAS16As found onhttps://smd.yooneed.one/

author: Zero999
author_rank: Super Contributor
timestamp: August 22, 2023, 10:36:34 am
content: This list I found doesn't have WRS, but WRs, which is says is a PNP transistor. I agree with Kean that it's moe likely a zener diode.https://www.sos.sk/pdf/SMD_Catalog.pdf

author: Faringdon
author_rank: Super Contributor
timestamp: August 22, 2023, 02:10:05 pm
content: Thanks,Do you knowSMA diode marked"RM72"?(Has kind of intertwined chain links logo thing...Which is the vishay logo)

author: Kean
author_rank: Unknown
timestamp: August 22, 2023, 02:47:57 pm
content: You'll need to make some effort. SMD markings are only a guide as they are often reused on similar parts.For a diode, try using the diode check feature on your DMM to see if it is a standard rectifier or Schottky type. To see if it is a Zener or TVS you'll want to try a low current limited supply.I have battery powered boost converter I made over 20 years ago for testing Zeners, it plugs into a DMM and generates about 100V DC with a short-circuit current of about 15mA. I usually run it from a mostly drained 9V battery so the output is a bit weaker.Did you even look at the links provided?
Solder balls occur when running T962 desktop reflow oven - Page 1
Forum section: electronics / general

author: hjfosse
author_rank: Newbie
timestamp: August 11, 2023, 02:28:10 pm
content: We are using a T962 for assembling smaller PCBAs in our workshop. We see that solder balls occur when running what we think is correct heating profile for the solder paste (Profile 5, paste type T3) I see that the solder balls can be caused by a lot of different factors. Any suggestions on what to try first?

author: asmi
author_rank: Super Contributor
timestamp: August 11, 2023, 10:24:47 pm
content: What kind of paste is it? These balls tend to occur if temperature is too high, or if it ramped up too quickly.

author: DavidAlfa
author_rank: Super Contributor
timestamp: August 12, 2023, 10:05:08 am
content: Yeah it sounds like it's heating too fast, the flux will boil and spread all over.

author: jmelson
author_rank: Super Contributor
timestamp: August 12, 2023, 11:00:14 pm
content: I used to see this stuff all the time. Once I switched to GC10 paste, I very rarely saw the balls. Wonderful stuff! (I'm soldering in a toaster oven, too!)Jon

author: hjfosse
author_rank: Newbie
timestamp: August 18, 2023, 06:32:26 am
content: Thanks for the suggestions. We will try ramping down the heating profile. Will also test out the GC10 paste.

author: RoGeorge
author_rank: Super Contributor
timestamp: August 18, 2023, 06:44:48 am
content: Could be the low quality of the soldering paste, improperly stored or expired.Once I've tried the much cheaper soldering paste used for fitting construction copper pipes. That paste is also made of small solder balls mixed with flux, just that when heated it was spraying solder balls all over the PCB.
Which pad is cathode? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: October 01, 2023, 02:58:20 pm
content: Hi,Please could i check, the page 4 appears to suggest that big pad is cathode?https://www.diodes.com/assets/Datasheets/ds30784.pdf

author: isometrik
author_rank: Regular Contributor
timestamp: October 01, 2023, 03:01:49 pm
content: Look at the "Package Outline Dimensions" on page 4. The thick vertical bar is the cathode... and it does correspond to the larger pad.
help finding DIN43650 (solenoid valve) pcb mount hardware  - Page 1
Forum section: electronics / general

author: solarfern1
author_rank: Newbie
timestamp: August 17, 2023, 03:05:45 am
content: Hi all,I'm looking to source these solenoid valve connectors to re-create this out of production PCBA, has anyone come across custom metal contacts like this before ?I can mostly just find moulded or complete cable assemblies, i'd like to find the female pins as well as the male tall onesany suggestions would be greatly appreciatedCheers,Randal

author: ajb
author_rank: Super Contributor
timestamp: August 18, 2023, 02:51:47 pm
content: Hmm, the U-shaped pins might be tricky, but there are PC-mount quick-connect terminals all over the place that could work with flat terminals.Keystonewould probably be a good place to start.If you're doing enough volume, you could look into getting custom stampings made. The production cost on the parts is low, but you need to make enough of them to amortize the tooling cost to a reasonable level.
PCB stickers/laser engraving for double sized PCBs - Page 1
Forum section: electronics / general

author: Prometheuz_ZAT
author_rank: Newbie
timestamp: August 14, 2023, 08:37:31 am
content: Hello,I'd like to know how are PCB assebly lines working with stickers/engraved serial numbers. For a single sided PCB that's simple, it's just somewhere on the TOP side and assembly machines scan it. But what about double sided ones? Those of you that work in PCB assebly lines and are scanning serial numbers, do you have just one sticker and an extra scanner searching for the sticker on the bottom side? Or do you have a sticker on each side with the same information in it?If we use just one sticker I have to figure out a way to scan it from the BOT side.Any information is going to be very helpful.

author: Jackster
author_rank: Frequent Contributor
timestamp: August 14, 2023, 08:57:34 am
content: Quote from: Prometheuz_ZAT on August 14, 2023, 08:37:31 am2 cameras. 1 top, 1 bellow.

author: Gribo
author_rank: Frequent Contributor
timestamp: August 14, 2023, 03:31:28 pm
content: 2 Industrial barcode scanners that can cover an entire panel, top and bottom. Yes, these are basically cameras these days.
Clearance from isolated LV secondary to earthed metal chassis? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: August 13, 2023, 02:06:40 pm
content: Hi,If you have an offline isolated SMPS, to full reinforced insulation level....and the vout is 24v...how far do the nets of that isolated secondary need to be from the earthed metal chassis?Surely if they are 1mm away from the chassis thats fine?
3mm Gap between  TO220 and HEATSINK - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: August 23, 2023, 11:43:19 am
content: Hi,We have a metal tabbed TOPswitch TO220 (6 pin) mounted vertically, tho' its 3mm from the metal heatsink which is vertical behind it........we have a screw hole in the heatsink which is same height as for TO220.How would we best fill this 3mm gap?Its the switching FET of a 90-265VAC flyback of 80W max.

author: wraper
author_rank: Unknown
timestamp: August 23, 2023, 12:00:19 pm
content: Place a 3mm thick aluminum shim between them.

author: Matt-Brown
author_rank: Regular Contributor
timestamp: August 23, 2023, 01:45:56 pm
content: Form the leads on the to part so it has "dog legs", then solder that into the board and no more gap

author: tggzzz
author_rank: Super Contributor
timestamp: August 23, 2023, 04:01:09 pm
content: Quote from: wraper on August 23, 2023, 12:00:19 pmOr to improve conductivity, use a BeO shim

author: wraper
author_rank: Unknown
timestamp: August 23, 2023, 04:15:35 pm
content: Quote from: tggzzz on August 23, 2023, 04:01:09 pmCopper would be better and way cheaper. Not to say that BeO is carcinogenic and good luck getting it these days. EDIT: Oh, I guess it's cunning plan how to get rid of woods.

author: tggzzz
author_rank: Super Contributor
timestamp: August 23, 2023, 04:30:51 pm
content: Quote from: wraper on August 23, 2023, 04:15:35 pmDrat. I've been rumbled

author: TimFox
author_rank: Super Contributor
timestamp: August 23, 2023, 04:34:28 pm
content: A short list, derived from different manufacturers' tables.The thermal conductivity values depend on temperature and material properties, especially variations in ceramic poly-crystalline structure.Yes: BeO is a serious inhalation health hazard.One of my professors lost a lung due to berylliosis contracted during the Manhattan Project.All conductivity values are metric: W m-1K-1(not to be confused with mK milliKelvin).The metal values are for pure material: alloys like steel have much less conductivity.Metals:Silver 420Copper 400Gold 310Aluminum 240Iron 70CeramicsBeO 280AlN 230SiC 100Al2O345For any of these materials used to fill a 3 mm gap, it is useful to use thermal grease (or equivalent) on both interfaces to fill microscopic air gaps between surfaces that increase the thermal resistance.
SMT550 Problem - Page 1
Forum section: electronics / general

author: stefangem
author_rank: Newbie
timestamp: June 06, 2023, 06:26:16 am
content: HelloThis machine SMT550 is driving me crazy.One component is empty and I want to turn it off. I do that with a hook off. This is ok, the component is now without assemblingBUTI bought a component and want to activate it again.NO CHANCE.The machine ignores it no matter what I do.regrouping doesn't work either or I'm doing it wrong.How exactly do you group or have another Idea to activate the component?RegardsStefan

author: sinewave
author_rank: Unknown
timestamp: June 06, 2023, 01:00:36 pm
content: Explain in more detail as I'm struggling to understand what you are referring to?

author: alexig
author_rank: Contributor
timestamp: June 06, 2023, 02:26:52 pm
content: In SMT Run tab, you need to go into the settings and enable the tick box there for the part

author: eflyersteve
author_rank: Contributor
timestamp: August 07, 2023, 03:48:18 pm
content: I have a new SMT-550X and am having the same issue. When running my first boards, I was having issues with two components. I chose to skip those two components. I have corrected the issue but no matter what I do, those parts are ignored when assembling. It isn't even attempting to place these two parts on this assembly even though other assemblies they are placed. For the life of me I can't find where to correct this issue. I've checked in the SMT run settings and have found nothing corrects this issue. Any suggestions would be greatly appreciated. I suppose I could re-build the program from scratch but don't want to.Edit to add: I can move this part to a different feeder location and it works. Still have no idea how to get two of my feeder locations to function though.

author: alexig
author_rank: Contributor
timestamp: August 10, 2023, 03:01:12 pm
content: I've skipped parts before and have re-enabled them without problems. Strange that you had to move it to a different feeder location. Did you see the part checkboxes in the SMT run settings?You could try to reach out to their support rep Ekko via Skype on live:191983573
GreenPCB  - Page 1
Forum section: electronics / general

author: xavier60
author_rank: Super Contributor
timestamp: July 13, 2023, 12:10:17 am
content: Anyone know where their PCBs are manufactured?https://greenpcb.com.au/pcb-fabrication/standard-pcb/A mention of "China" here,https://www.electronicsonline.net.au/content/assembly/product/greenpcb-pcb-manufacturing-and-assembly-901794084

author: Mangozac
author_rank: Frequent Contributor
timestamp: July 13, 2023, 01:02:56 am
content: Why don't you just ask them?

author: mengfei
author_rank: Regular Contributor
timestamp: July 13, 2023, 01:28:19 am
content: this should give you some ideai see chinese writings but could be thailand but most likely...

author: stone
author_rank: Contributor
timestamp: August 09, 2023, 03:34:19 pm
content: factory in china
Paste mask expansion for PTH pad? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: August 09, 2023, 08:56:31 am
content: Hi,Do you agree, paste mask expansion is irrelevant for a PTH pad?PTH pads dont get paste put on them.

author: Psi
author_rank: Super Contributor
timestamp: August 09, 2023, 09:13:03 am
content: Normally yes. Unless you decide you want paste on them.For example maybe you are doing via-in-pad and you want paste there because a BGA is going on top.
Sourcing this harness / connector - Page 1
Forum section: electronics / general

author: brandon.arnold
author_rank: Contributor
timestamp: July 25, 2023, 06:20:43 pm
content: May I ask if anyone can source this harness / connector part? I have looked all over and emailed the folks at their page a couple weeks back to no response. I would love to have the original parts on-hand before I go modding it.

author: thm_w
author_rank: Super Contributor
timestamp: July 25, 2023, 10:02:05 pm
content: What is the pitch?Looks like JST SM:https://www.pcboard.ca/jst-sm-2-pin-connector-setCan get them from digikey, amazon, aliexpress, etc.

author: brandon.arnold
author_rank: Contributor
timestamp: July 26, 2023, 09:03:38 pm
content: Whoa. I think that's it! 2.5mm pitch would not surprise me at all. Thanks, @thm_w!

author: stone
author_rank: Contributor
timestamp: August 03, 2023, 08:48:17 am
content: SM2.54

author: tooki
author_rank: Super Contributor
timestamp: August 07, 2023, 06:02:49 am
content: Quote from: stone on August 03, 2023, 08:48:17 amNope. AliExpress and other Chinese sites routinely misname many 2.50mm pitch connectors as 2.54mm. JST SM is 2.50, not 2.54mm.

author: stone
author_rank: Contributor
timestamp: August 07, 2023, 02:00:53 pm
content: This male and female connector is called SM2.54 in China. The actual spacing is 2.5mm. The unit price of 2P to 12P also ranges from US$0.05 to US$0.25
Cheaper way to make a Rigid-Flex board? - Page 1
Forum section: electronics / general

author: Gabe_from_Onda
author_rank: Newbie
timestamp: May 22, 2023, 04:56:02 pm
content: Hi,I'm looking to make a PCB that pretty much has to include a flexible PCB section or connect to separate flexible PCBs. It's still in the R&D stage but I'm only expecting to sell ~50 of the product per year, so there's not a lot of economies of scale even once it hits the market. The section that's going to have surface mount components is only ~10mm x 25mm. The flexible section only needs to have a 2" bend radius.Would it end poorly if I just ordered a flexible PCB with a 0.8mm rigid backing on the SMT area and removed the cover film from that entire area? It would save a bit of cash, but I'm worried it would end up breaking. The other options I see would be to put FPC connectors on a rigid board and connect separate FPC boards, or to just shill out the cash for a properly made rigid-flex PCB.

author: langwadt
author_rank: Super Contributor
timestamp: May 22, 2023, 07:08:44 pm
content: you can get solderable flat flex

author: stone
author_rank: Contributor
timestamp: August 05, 2023, 04:53:18 am
content: 1.You can use this rigid-flex design.2.use this welding method
Finding actual Chinese manufacturer for bulk ordering - Page 1
Forum section: electronics / general

author: phil from seattle
author_rank: Super Contributor
timestamp: July 11, 2023, 06:37:36 pm
content: I see a lot of modules for sale from various AliExpress stores. Often times many stores have exactly the same modules for sale, offered at single unit pricing. If I wanted to buy more than a few, say 100, they offer a 1 or 2% discount. How do I go about finding the actual manufacturer or upstream distributor to get a better price at higher volume? I've tried messaging the various stores for pricing on a larger number of units but never get any response. TaoBao or similar? Maybe I'm not asking the right way? Any pointers on how to go about doing this would be greatly appreciated.

author: Microcheap
author_rank: Frequent Contributor
timestamp: July 11, 2023, 08:05:55 pm
content: I think you are looking for some site like Alibaba:www.alibaba.comor Made in China:www.made-in-china.comthose are focused on wholesale and are the easiest way to find manufacturers and a lot of trading companies to order in volume from China.Just bare in mind that these kind of sites don't work quite the same way as Aliexpress or eBay, normally the prices listed there are just to grab your attention. You will have to contact the company for a quotation as the real prices will depend on a number of factors (volume, personalization and so on).

author: edavid
author_rank: Super Contributor
timestamp: July 11, 2023, 08:17:49 pm
content: I thinkhttp://www.icstation.commay be close to what you want. They do offer quantity discounts on the standard modules.

author: Kean
author_rank: Unknown
timestamp: July 12, 2023, 12:09:03 pm
content: Often the actual manufacturer is not setup or able to deal directly, so a middleman/distributor is needed.Alibaba is the best place to start as mentioned above, but is not a simple shopping cart site but rather a way to negotiate and setup a trade agreement with escrow facility. I have used it a few times with no problems, but often I find it is just easier to find a good seller on AliExpress and after a trial order or two chat with them about bulk pricing. Other times, I've managed to find the original manufacturer based on the markings/labels on the device, tracked down their website and contact details, and then negotiated directly typically using PayPal for a little extra security.

author: phil from seattle
author_rank: Super Contributor
timestamp: July 12, 2023, 03:02:21 pm
content: Thanks for the suggestions. Very helpful.

author: stone
author_rank: Contributor
timestamp: August 03, 2023, 02:37:37 pm
content: What module are you looking for. Many online sales are not factories.
Melf resistors roll off the pads - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: July 22, 2023, 11:51:44 am
content: Hi,We have been told not to use MELF resistors, MMA0204, MMB0207 because they "roll about"...surely they get stuck in the solder paste and dont role?https://www.vishay.com/docs/28713/melfprof.pdf

author: Siwastaja
author_rank: Super Contributor
timestamp: July 22, 2023, 12:25:19 pm
content: Quote from: Faringdon on July 22, 2023, 11:51:44 amWould I agree? Yes, I would.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: July 22, 2023, 07:51:47 pm
content: They don't role for me. I passed their role on to pulse rated chips or THTs.If you're having problems, consider a glue step. More of a wave than reflow thing though.Tim

author: Matt-Brown
author_rank: Regular Contributor
timestamp: July 26, 2023, 01:21:50 pm
content: You can also have the stencil for paste designed witha u shape, the inside of the U stops the parts from rolling and as the solder melts it still goes onto the part and rest of the pad

author: Neilm
author_rank: Super Contributor
timestamp: July 26, 2023, 06:25:12 pm
content: Quote from: Matt-Brown on July 26, 2023, 01:21:50 pmI have done that when using MELF components in the past and have not had any issues with them rolling off

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 26, 2023, 07:35:30 pm
content: Use Duck Tape.
Neoden Frameless printer. Any users? - Page 1
Forum section: electronics / general

author: TankSparks
author_rank: Contributor
timestamp: July 21, 2023, 10:40:35 pm
content: Neoden Frameless printer. Any users?I can't find any video on it. Can't see how hard it is to use and how the PCB board mounts.Anybody else make frameless printers.

author: lutkeveld
author_rank: Regular Contributor
timestamp: July 22, 2023, 10:54:55 am
content: I have one. It's of decent quality.Mounting the board is a bit annoying and time consuming, but not different from many other manual printers.Adjusting the position (x, y, rotation) is quite smooth.Tensioning the stencil is okay, but overall it is better to get a pre-tensioned stencil, especially for small feature size.The main upside is that frameless stencils are cheaper (both in production, as in shipping). Over the long run, it pays out if you do any volume.If your volume is not that high, I would just go with a cheaper printer for framed stencils.

author: TankSparks
author_rank: Contributor
timestamp: July 25, 2023, 01:48:53 am
content: Why is it annoying to mount the board? Any pictures of the board mounted. Does the board require holes?

author: MR
author_rank: Regular Contributor
timestamp: July 25, 2023, 03:21:34 am
content: https://spide-smt.nl/portfolio-item/sd300/i use this one for prototype runs, I have no problems with frameless stencils I use to order them in a size that fits.Lately we did a large panel that almost used the entire size of the stencil printer and it also worked.The tensioning of the stencil more or less only depends on the strength of the spring which is used on both sides of the printerDoes the neoden use springs?If not I'd add them it's the key of having the stencil firm inside the printer, they're not so expensive and can be sourced just about everywhere (including a lock).I'm using a microscope to adjust the printer and match the QFNs, those 10$ microscopes can also do the job and verify the location.I would definitely recommend to use a microscope if you use this kind of stencil printer.

author: lutkeveld
author_rank: Regular Contributor
timestamp: July 26, 2023, 01:51:24 pm
content: Quote from: TankSparks on July 25, 2023, 01:48:53 amIts visible on their product pictures. Due to the way its designed you need to (un)tighten four relatively long bolts.Once tightened you are constrained to a relatively small area of movement, so you need to make your sure your stencil openings already line up with the PCB quite well. If its off too much, the X/Y adjustment will not be enough to make sure they line up.With the common 'put four PCBs around it and fix your stencil using tape' method, you have support on all sides of the PCB.With the neoden, once your squegee applies pressure outside the PCB contour, the part on the PCB might lift and cause smearing.Not saying its a bad product, I would buy it again for the volume im doing, but it has some downsides.With some effort and a 3D printer the mounting can maybe be done better, so with support on all sides and faster (un)loading speed.Have not taken the time to look into this DIY option yet.
Companies that can work with ceramic substrates  - Page 1
Forum section: electronics / general

author: Rayuela
author_rank: Newbie
timestamp: June 19, 2023, 12:02:53 pm
content: Hi Everyone,The attached picture shows a Blackrock connector commonly used in different Brain computer interfaces. I need to search for a company that can make a PCB or ceramic substrate job that will allow vias or pads to be metalized from one layer to the other with a pad size of 200-300µm and with a pitch between pads of 500µm.

author: PCBprototyping
author_rank: Contributor
timestamp: June 19, 2023, 12:51:20 pm
content: LaserMicronics is LPKF's company for services on LPKF's equipment, try them.LPKF manufactures UV laser systems, like ProtoLaser U4, that are capable of cutting ceramic boards.They also have via plating system, 0.2 mm via is the minimum size.

author: Rayuela
author_rank: Newbie
timestamp: June 20, 2023, 07:03:21 am
content: Thank you mate! I'll give them a try

author: stone
author_rank: Contributor
timestamp: August 09, 2023, 04:04:32 pm
content: Ceramic substrate
Multiple reference designator assignment - Page 1
Forum section: electronics / general

author: mushu326
author_rank: Newbie
timestamp: July 20, 2023, 09:07:17 pm
content: Hi,Recently I've been seeing multiple reference designators assigned to a single location. Designer mentioned that 1 refdes per flavor of the board, which is unacceptable to me.The designers are off-shores and I forgot what standard to educate them that it should only be 1 reference designator per location on the board. Can anyone chime in?

author: ajb
author_rank: Super Contributor
timestamp: July 21, 2023, 04:24:52 am
content: where are you seeing these reference designators? In a placement file? In a PCB CAD file? In the silkscreen on a board? Are these different designators for two parts of which only one is fitted at a time in the same footprint?
Inductor  silk screen and alignment - Page 1
Forum section: electronics / general

author: stephen Jones
author_rank: Newbie
timestamp: July 18, 2023, 03:18:14 pm
content: I have an inductor on a switch mode PSU, it is square with no polarity, and its pads are not visible from above. When I create the silk screen for the inductor how do I make sure its fitted by our manufacturer in the correct orientation and not 90 degrees rotated. Obviously they could just turn it over and check the pads and the obvious silk screen shape is a square but could that get us into trouble? Any pointers appreciated

author: ajb
author_rank: Super Contributor
timestamp: July 18, 2023, 04:20:04 pm
content: Getting that sort of thing right is pretty much PCB Assembly 101. The manufacturer will need to verify component orientation out of the tape versus the footprint anyway, since in-tape orientation varies and they don't immediately know what the 0° orientation of your footprints are. Any decent manufacturer will contact you to clarify anything that isn't pretty obvious. If the inductor has any markings at all that show its orientation, like printed text, the manufacturer may use those for verification--many optical inspection systems can read component text to verify correct orientation and fitment, so they would be programming that as part of the job setup anyway.

author: Matt-Brown
author_rank: Regular Contributor
timestamp: July 19, 2023, 07:01:07 pm
content: When we build a first prototype for a customer we put double sided tape on the boards. Then we palce the parts and then engineering (me) picks the parts off and verifies every single rotation. We then use that now known good board to make an AOI program. When the assembly goes to production mode that aoi program verifies all the parts are correct
Where to put the flipper?  - Page 1
Forum section: electronics / general

author: loki42
author_rank: Frequent Contributor
timestamp: July 19, 2023, 01:25:16 pm
content: I'm the proud owner of a board flipper that I got for free... I am however not the proud owner of any idea where to put it in the line or really what to do with it. I got it thinking it for be useful as a conveyor anyway with flipping off but... if you're doing dual side boards where do you put it? After oven before unloader? Or before printer after destacker / start of line loader? I'm not sure how else they are used...

author: SMTech
author_rank: Frequent Contributor
timestamp: July 19, 2023, 03:49:14 pm
content: If it were me ... before the unloader but after Reflow/AOI. But this all depends on your line setup, and workflow, the end makes more sense to me than the beginning tho'
Smallest VIA size on pcbway without extra cost - Page 1
Forum section: electronics / general

author: mrburns
author_rank: Contributor
timestamp: July 15, 2023, 06:39:43 pm
content: I was unable to find out the answer from the pcbway website that what is the smallest VIA size on pcbway without extra cost. This question is related to my other post on the beginners forum:https://www.eevblog.com/forum/beginners/(pcb-review-request)-pi-zero-breakout-for-sensors-3-30v-regulated-input/

author: ataradov
author_rank: Super Contributor
timestamp: July 15, 2023, 06:53:34 pm
content: At least If you try to place the order, you are given multiple options. 0.25 mm is the smallest at the same price. At 0.2 mm you get a significant bump on prototype quantities. The increase is less significant on the large quantity orders. And at 0.15 mm, the price increase is even more significant.

author: DavidAlfa
author_rank: Super Contributor
timestamp: July 15, 2023, 07:02:45 pm
content: Same as jlcpcb, 0.3mm drill hole, I used 0.4mm vias without problem.Checkthis pictureout for details.Good luck soldering the TPS55289!Why choose a so complicated device/footprint?The're gazillions of buck converters capable switching 24V into 5V 500mA, and you have enough free space in that board for several football fields :-).

author: mrburns
author_rank: Contributor
timestamp: July 15, 2023, 09:26:27 pm
content: Quote from: DavidAlfa on July 15, 2023, 07:02:45 pmI will order the PCB with all SMDs assembled. I hope that they are able to pull that off.As of why this decided to go with this device is that Im really looking forward to test and experiment with the I²C interface of that chip. For this and future use.So if I try to keep the VIA diameter at 18mil and I put hole size to 10mil would they be able to do it without extra cost?
Better stand for Hakko FR-301 desoldering tool? - Page 1
Forum section: electronics / general

author: 6SN7WGTB
author_rank: Regular Contributor
timestamp: July 04, 2023, 06:59:27 pm
content: Not convinced by the looks of the Hakko C1100 - unless people here would recommend?If not, any better recommendations?Thanks

author: AnalogAficionado
author_rank: Newbie
timestamp: July 04, 2023, 11:50:33 pm
content: I bought one. It's... OK. Not great (and not pretty), but it gets the job done.Seemed like a better option to me than the Hakko 633-01 other people sometimes recommend, which looks too lightweight. At least the C1100 has a weighted base.Curious if anyone's tried both, since I haven't had a chance to compare them in person.
Peelable hot melt adhesive as a conformal coating? - Page 1
Forum section: electronics / general

author: e100
author_rank: Frequent Contributor
timestamp: August 15, 2023, 03:43:36 pm
content: Otherwise known as 'credit card glue', 'glue dots' or 'fugitive glue' , the little blobs of glue that temporarily stick your bank card to the sheet of paper that arrives in the post.Has anyone tried to use something like this as a moisture barrier on PCBs that can still be removed later on due to its fugitive nature?

author: Jackster
author_rank: Frequent Contributor
timestamp: August 15, 2023, 04:05:07 pm
content: Booger glue does not work well with high humidity so won't protect your electronics from moister.AFAIK it actually absorbs moister so would be worse than no conformal coating.I have a new CC at home still in the letter. Ill rinse it in water and see what happens.

author: thm_w
author_rank: Super Contributor
timestamp: August 15, 2023, 09:02:18 pm
content: https://www.gluegunsdirect.com/2013/01/what-glue-is-used-to-stick-credit-business-cards-to-letters/I don't know of anything that is easily removeable. There is re-enterable compound which dave has mentioned multiple times.There are also nano coatings, which provide some protection for the board but will easily burn away.https://www.paryleneconformalcoating.com/conformal-coating-education-center/nano-coatings/

author: jpanhalt
author_rank: Super Contributor
timestamp: August 15, 2023, 09:12:41 pm
content: All conventional hot melt is easily peelable with a little isopropyl alcohol. I have never needed to do that with booger glue, but it is likely to work there too.

author: SMTech
author_rank: Frequent Contributor
timestamp: August 16, 2023, 12:23:55 pm
content: What about a potting gel? Something like thishttps://www.raytech.it/en/product/low-voltage/fillers/gel/magic-gel

author: e100
author_rank: Frequent Contributor
timestamp: August 17, 2023, 05:29:49 am
content: Quote from: SMTech on August 16, 2023, 12:23:55 pmit's a low viscosity liquid so you need to build a dam to keep it in place until it cures.I was looking for something that you could selectively apply using a glue gun.

author: SMTech
author_rank: Frequent Contributor
timestamp: August 17, 2023, 01:17:50 pm
content: There are many variants, who knows maybe some of them start out more viscous than others.. Of course they are best used inside an enclosure or... eww.Quite a few encapsulating/conformal/underfill compounds require a damming boundary laid down first.
Sending cut-tape parts to China for assembly - Page 1
Forum section: electronics / general

author: davekeck
author_rank: Contributor
timestamp: July 05, 2023, 03:41:19 am
content: Hi all,I'm outsourcing board assembly to China (NextPCB) for the first time. Of the parts required for assembly, I'm sending them 17 parts, and they're sourcing 24 parts.The parts that I'm sending are in cut-tape form, which I know is not ideal. NextPCB's website suggests they accept cut-tape (not totally clear though), and when I double-checked (and triple-checked) with their support staff, I got some conflicting answers (language barrier + non-technical folks?) so I don't have high confidence that they accept cut-tape.I'm eager to have this assembly go smoothly so I was looking for some advice from more experienced folks: should I send cut-tape parts or put the cut-tape on reels (including leaders + trailers) and send reels? The risk of sending cut-tape parts is that they don't accept cut-tape, or they waste lots of parts due to missing leaders. The risk of reeling them myself is I'm a noob and my splice could jam their machine, or I could make some other noob mistake in reeling. (And good-quality splice tape seems scarce and expensive.)Also it seems like NextPCB must deal with cut-tape since they source from Mouser and Digi-Key, who don't offer reeling service for all of their parts...Thanks!

author: Kean
author_rank: Unknown
timestamp: July 05, 2023, 05:27:29 am
content: I've never dealt with NextPCB but I'd suggest that any CM will have plenty of experience with cut tape, and thus I'd let them deal with it. I've done this with various (local to me) CMs with no complaints... but probably some swearing behind the scenes. If you don't have experience with splicing cut tape then you are likely going to make life even more difficult for them.Just be sure to supply additional components. I aim for at least 50pcs of jellybean parts like SMT resistors/caps/diodes, and 5 pcs of any larger semiconductors. More if possible, with the exception of expensive parts. If they run out, then you'll likely get a short supply of finished goods.

author: MLGBZDSB
author_rank: Contributor
timestamp: July 06, 2023, 02:17:21 am
content: NextPCB is good, some of my old client cooperated with them!Certificate from China
Manage inventory of components - Page 1
Forum section: electronics / general

author: VEGETA
author_rank: Super Contributor
timestamp: June 23, 2023, 09:48:46 pm
content: Hello,I am about to get some components from Alibaba suppliers, components are nice according to my needs. mainly just connectors like RCA and DSUB15... cost a lot less than usual. a sample is coming soon.however, i want to buy in bulk and send to my suppliers as needed since alibaba suppliers are kinda pain to talk to, due to language barrier and slow response sometimes.I thought of using my account in nextsmartship but support told me stuff need to have individual barcode on each component which is painful.. a suggestion from them is to define the item as one box, and i let my alibaba supplier send say 100 connector in 1 box with a barcode on the box... shipping company will treat it as 1 item with quantity of 1. and i ship the entire box.I was hoping of a solution better than this if you can... besides the idea of taking the items to me since customs and stuff will be hard.
Advice on solder flux/paste - Page 1
Forum section: electronics / general

author: sacentre
author_rank: Contributor
timestamp: June 20, 2023, 02:53:35 pm
content: I've been using these low-cost rosin based soldering fluxes for years (see photos) with the traditional 60/40 solder for general electronics assembly - mostly just hobby kits, occasional repair work and recently some smt assembly etc (I haven't yet tried using solder paste with hot air for soldering ICs).Since I'm about to order a fresh supply, I thought I'd ask first if anyone had any views about "better" alternatives. I see a huge range of prices for flux pastes and liquids etc. I'm assuming there's a reason for this and wonder if there's anything to be gained from paying more for a different type or brand.Right now though I've no idea exactly what advantage a "better" flux would offer since my experience is limited - improved flow? cleaner joints?Can anyone advise?TIA

author: David Hess
author_rank: Super Contributor
timestamp: June 20, 2023, 04:22:20 pm
content: Some work better than others, but there is no way to know which without testing.Kester's 44 (now 1544?) flux in liquid and paste is excellent but no longer generally available.

author: thm_w
author_rank: Super Contributor
timestamp: June 20, 2023, 09:14:35 pm
content: I don't know about "better" but its more convenient to have the paste flux in a syringe. I use either the generic noclean amtech clones or the MG chemicals paste.https://mgchemicals.com/products/soldering-supplies/soldering-flux/soldering-flux-paste/https://www.aliexpress.us/item/4000258887808.htmlBig clive mixes up his own liquid version with IPA in a little dropper bottle. Thats probably the cheapest liquid option.

author: asmi
author_rank: Super Contributor
timestamp: June 21, 2023, 03:20:31 pm
content: I use this flux:https://www.chipquik.com/store/product_info.php?products_id=310004Highly recommend, works like charm, and is easy to wash away after soldering!

author: tooki
author_rank: Super Contributor
timestamp: June 22, 2023, 06:57:01 pm
content: Quote from: sacentre on June 20, 2023, 02:53:35 pmThe Felder flux you show is NOT for electronics! Zinc chloride fluxes are for coarser electrical and mechanical work only. Do not use them on stranded wire.

author: wraper
author_rank: Unknown
timestamp: June 22, 2023, 07:37:18 pm
content: Good fluxes for electronics never come in tin jars. Either not good or not suitable for electronics at all.

author: wraper
author_rank: Unknown
timestamp: June 22, 2023, 07:43:05 pm
content: https://www.felder.de/products/metal-construction-industry/soft-soldering/fluxes-for-cu-cu-alloys/loetfett-243100501.htmlQuoteAnd even on pipes you still need to wash it off to avoid corrosion. As of electronics, zinc chloride is nearly impossible to wash off entirely as it penetrates PCB substrate.

author: tooki
author_rank: Super Contributor
timestamp: June 23, 2023, 08:52:14 am
content: Quote from: wraper on June 22, 2023, 07:37:18 pmYep. Though they used to! (I still have a tin of Kester 44 from the early 1990s.)
Do IPC class 1 only fab houses exists - Page 1
Forum section: electronics / general

author: qwaarjet
author_rank: Regular Contributor
timestamp: June 20, 2023, 10:44:53 pm
content: So I'm currentlybeing forced intogoing through formal IPC WHMA 620 +space addendum training and as far as I can tell the only reason for class 1 to exist to trick me on the module exam questions, because what is obviously terrible for class 2,3 quality might just be meh for class 1. So my question is are there any fab houses that are IPC trained but only do Class 1 work if so why, if not what the point of having a class 1 since anyone doing IPC training would never do class 1 work

author: Matt-Brown
author_rank: Regular Contributor
timestamp: June 21, 2023, 06:20:19 pm
content: It all depends on customerYou may have a design where you cannot meet class 2 or 3.We have had one class 1 assembly prodcut due to the design. We had to have the customer waver our normal Class 3 if specified, but usually class 2 standards.We hve also had customers that specify parts, but do not account for lead spacing or meniscus in hole issues. We gethtme to waiver it down to class 2, or if they want class 3 have to find ways to keep small t/hole caps out of holes. Then we charge them more since it was due to the design.Our inspectors are J-std and ipc 610 class 3 certified, and we try to do class 3 all the time, so specify when we cannot meet that (contract agreement over rules all).
GaNFET soldering - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: April 20, 2023, 05:47:40 pm
content: Hi,We wish to use EPC2204A GANFET in out 37V, 20A supercap charger (supercap to 6v).The following says we need solder mask defined pads, and the pads are oval.How can we get an oval solder mask window in Eagle pro?...or can we just get away with doing a square pad opening as its only a prototype?(we wonder if KICAD can do oval solder mask windows?)https://epc-co.com/epc/Portals/0/epc/documents/product-training/Appnote_GaNassembly.pdfEPC2204A GANFEThttps://epc-co.com/epc/Portals/0/epc/documents/datasheets/EPC2204A_datasheet.pdfAll thermal vias in pad must be plated...but minimum dims means a min 150um drill hole and a 150um rest ring....that will be difficult to fit in these pads as they are only 0.5mm pitch?Do you think its at all possible to hot air + solder hotplate solder the EPC2204A?

author: thm_w
author_rank: Super Contributor
timestamp: April 20, 2023, 09:24:06 pm
content: Kicad can do it, edit the footprint, then draw a line on the soldermask layer. I'm sure you can do the same in Eagle.Don't know what you mean about the vias. They do a good job explaining in the PDF you linked to either used filled via in pad, or if that is not possible, place them beside the pads and tent them.

author: JohnG
author_rank: Frequent Contributor
timestamp: June 21, 2023, 04:57:41 pm
content: Perhaps this reply is too late, but EPC has a set of instructions for manual placement of parts here:https://epc-co.com/epc/Portals/0/epc/documents/application-notes/How2AppNote003%20Assembly.pdfThere are some very old videos showing how to do attach/removal with hand tools. Note that the videos differ from the above instructions in that the video relies on the solder already present on the die. This works and is ok for prototyping, but if you are using a new PCB with no solder on the pads (the usual case because HASL is specifically not recommended for any chip-scale parts), it is best to put solder on the pads. The new instructions explicitly state this, but if you are doing rework, it can be pretty tricky to clean the pads and place solder without a stencil.Attachment:https://youtu.be/Dz8uRmQKDAMRemoval:https://youtu.be/K2cKeQjtZQgBest to practice on a few boards first. Reflow with stencils is highly recommended over hand placement.John
Capacitors from Dongguan Kuan Kun Electronic Co ? - Page 1
Forum section: electronics / general

author: twospoons
author_rank: Frequent Contributor
timestamp: June 22, 2023, 09:37:19 pm
content: Has anyone had any experience with this company and their capacitors, good or bad? I think our CM is having trouble sourcing parts from our usual suppliers (the well known big capacitor brands) and is suggesting this as an alternate, but we know nothing about the company or its products.Any advice would be greatly appreciated.

author: mon2
author_rank: Frequent Contributor
timestamp: June 23, 2023, 08:46:02 pm
content: What type of caps are you after?Ceramics? Try CCC or Walsin. Have offshore suppliers for both.Post more details if it is different.

author: schmitt trigger
author_rank: Super Contributor
timestamp: June 24, 2023, 04:31:45 pm
content: You are not alone. A myriad small companies are going thru the same ordeal.Unless your company is a large corporation, or a smaller contractor being helped by a major corporation purchasing several million components per year, sourcing from the major, known capacitor brands is going to be, to put it mildly, a challenge.You should start a second-source validation test ASAP.

author: mawyatt
author_rank: Super Contributor
timestamp: June 24, 2023, 04:55:23 pm
content: Quote from: schmitt trigger on June 24, 2023, 04:31:45 pmExactly, awkward but undeniable situation for us small folks, and why we invested in a couple quality bench lab grade LCR meters!Best,

author: onsenwombat
author_rank: Contributor
timestamp: June 25, 2023, 11:31:18 am
content: Electrical specs for an off the reel component (not going to touch the topic of whether the first batch(es) are some special screened stuff, you'd not be the first to encounter such anyway) are one thing. Reliability and durability completely different one, which is obviously nothing you'll solve in a heartbeat. If you value any of such, stick with either proven manufacturers or buckle up for rather intensive testing.

author: MLGBZDSB
author_rank: Contributor
timestamp: June 30, 2023, 08:22:28 am
content: I know Kuan Kun, 20years something experiences, but absolutely not a major manufacturer.My advise: double check the specs with them, and get yourself as long NET as possible.
Encapsulating a key fob remote control - Page 1
Forum section: electronics / general

author: e100
author_rank: Frequent Contributor
timestamp: June 18, 2023, 04:18:33 am
content: Has anyone successfully encapsulated or weatherproofed a small button operated remote control device like this?I sort of imagine making an envelope using PEVA plastic sheet and somehow welding the seams like on these food bagsCommercially I believe these are made use 27MHz RF welding equipment, however all I have is a hot air soldering station.PEVA seems like a good choice as it's soft enough to allow the buttons to be easily pressed, but is also tougher than the plastic typically used for disposable food bags.My previous attempt at waterproofing involved wrapping it with self fusing butyl electrical tape but the added thickness makes it difficult to locate the 4 button positions and the tape stretches too much to be used as an anchor point for a key ring or lanyard.(This particular remote uses Zigbee in the 2.4GHz band)
BMP280 / BMP388 - Page 1
Forum section: electronics / general

author: artag
author_rank: Super Contributor
timestamp: June 12, 2023, 12:37:27 pm
content: There are huge numbers of breakout boards with a BMP280 pressure sensor available from asian sources, but Bosch made it obsolete in 2018. Mouser show it as not availble to order and offers BMP384, 390 and 581. LCSC have a few thousand 280 and a few hundred 388.The recommended replacement seems to be the BMP388 at a much higher price on a board and about twice the price as a bare device.Is the BMP280 widely cloned or are there just lots in the channel ? I've been using it for some time and must surely have encountered clones by now but haven't noticed any particular problems. Perhaps I just need to test them more thoroughly.

author: thm_w
author_rank: Super Contributor
timestamp: June 12, 2023, 09:10:37 pm
content: LCSC has 10,000 of the BMP280's in stock. Winsource claims to have 500,000.This Sencoch looks similar, although the can cutout is in a different spot:https://www.lcsc.com/product-detail/Pressure-Sensors_Sencoch-Semiconductor-GZP6816D_C3038127.htmlThere are the odd Aliexpress review saying they got bad readings, but, who knows if that was the fault of the user or the part..Have you compared multiple units side by side to see if they read within a reasonable range? Or do you have a reference device to measure temp/humidity accurately.

author: artag
author_rank: Super Contributor
timestamp: June 17, 2023, 11:47:24 pm
content: I haven't done any thorough testing. I think I may have seen some that are less sensitive but am by no means sure of that.I should do it (though I will probably use a newer device for production - the old stocks may suddenly disappear.I was mostly just curious as to whether other people (who may be better informed than me about supply chain issues) were aware of fakes.

author: floobydust
author_rank: Super Contributor
timestamp: June 18, 2023, 12:00:07 am
content: I have not seen any fakes, there might be some with no calibration though as a wild guess how to make them on the cheap.The part is light sensitive, as well as wash/flux chemical sensitive.There was a (Bosch) firmware bug where the EEPROM calibration constants would not get loaded properly unless you gave a power up delay I think 10 usec. Check your library code. I never found the Adafruit library to work, the accuracy was wrong as well and I changed to another and it worked fine.