How to solder 8VSSOP? - Page 1
Forum section: electronics / general

author: Faringdon
author_rank: Super Contributor
timestamp: June 18, 2024, 06:55:22 pm
content: Hi,I just soldered 8VSSOP by blob soldering all pins on each side...then changing to a "witches hat" superthin tip, and jamming it between the legs till the shorted legs were separated again...worked like a dream...is this a bona fide technique?...wish i'd known it before.It was an LM5021-2https://www.ti.com/product/LM5021

author: Gyro
author_rank: Super Contributor
timestamp: June 18, 2024, 07:13:10 pm
content: Repeatedly "jamming" the tip between the IC legs doesn't sound like a good technique for removing solder bridges, from the risk of bending legs, lifting pads and general thermal stress. Normally people buy flux and use it while SMD soldering to remove excess solder and bridges (mostly avoiding them in the first place) by enhancing the solder's surface tension.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 19, 2024, 06:13:38 am
content: Or they use a hollow spoon tip for it. Apply flux to the legs of the IC, fill the tip with solder and drag it along the legs.Here a chisel tip is used, but it works even better with a tip likethis.

author: Buriedcode
author_rank: Super Contributor
timestamp: June 20, 2024, 03:04:17 am
content: Wtf? I know you like your power supplies so probably solder some quote large (= heatsink) components, but does that mean you're trying to solder a 0.5mm pitch SMD with a frying pan? You shouldn't need to forcefully remove solder bridges with a specific tip..Just use flux and you can solder all pins on one side at once - its quite difficult to get bridges with decent flux, even a small amount, unless you've got your temps screwed up. Honestly it sounds like your technique is what people did before they had temperature controlled irons and used plumbers solder..

author: mtwieg
author_rank: Frequent Contributor
timestamp: June 20, 2024, 12:29:55 pm
content: This sort of package doesn't really require any special tools or techniques (they won't hurt either)... but I wouldn't remove a "blob" by applying a soldering iron directly. Solder braid and a chisel tip with maybe a tiny bit of flux should do a better job.

author: Faringdon
author_rank: Super Contributor
timestamp: June 20, 2024, 07:27:07 pm
content: Thanks for the youtube shot in #2 above....you can see he does it, and it comes out poorly...then in the next clip...he suddenly has wonderful joints...so there's some kidology going on there.All these videos have brand new tips.Brand new flux...they dont use the old stuff that most labs have.

author: Gyro
author_rank: Super Contributor
timestamp: June 20, 2024, 08:32:26 pm
content: Quote from: Faringdon on June 20, 2024, 07:27:07 pm<Very deep sigh!>Just go and buy a flux pen from RS, Farnell etc. (not China). There is Zero magic involved and zero "kidology", it works as described. Really treez, you'll do ANYTHING to avoid spending any money!How do you know the tips in the videos are brand new? They just look to be in good condition and properly tinned [EDIT: The tip in the #2 certainly isn't brand new, I can see that immediately from the appearance of the non tinned portion]. I suspect that yours are just so horribly mistreated that they just look new to you.I really can't believe that you've been in the industry for so long, insomany jobs and never had to solder a small pitch smd. You sound so pleased with your 'discovery' in your first post. You are a lost cause!

author: tooki
author_rank: Super Contributor
timestamp: June 20, 2024, 08:39:46 pm
content: Quote from: Faringdon on June 20, 2024, 07:27:07 pmUmmmm… I wanna know what you’re smoking.Flux and skill. That’s what it takes. Flux you can buy, skill you gain with a bit of practice. Well, probably notyouin the singular, since you seem uniquely resistant to learning anything. But normal people can learn to solder well.

author: zapta
author_rank: Super Contributor
timestamp: June 21, 2024, 02:13:23 am
content: If you want good results, use flux. It makes a big difference in SMD soldering. Use thick or tacky flux rather than thin liquid. Amtech flux has good reputation but there are others.Then you will get to board cleaning which is also a useful skill.

author: pcprogrammer
author_rank: Super Contributor
timestamp: June 21, 2024, 06:03:39 am
content: Quote from: Faringdon on June 20, 2024, 07:27:07 pmIt works exactly like that, even with old flux or crappy flux. A bit frugal myself, so I do it with the cheapest shit I can get and manage to get it done, and yes sometimes it means going back and remove a solder bridge. Apply an extra bit of flux, clean the tip, and drag it across the bridge.Quote from: tooki on June 20, 2024, 08:39:46 pmI'm sure he is not alone in being resistant to learning.Some will never gain in skill with practice. As an example from a totally different field of using your body, arborist tree climbing. I did a course because we have a lot of trees that once in a while need dead branch removal, and had no problems with it at all. The instructor told me about another student of him, that would never learn, even though the guy was very persistent in trying. Lack of certain motor skills and insight.

author: Faringdon
author_rank: Super Contributor
timestamp: June 25, 2024, 05:55:47 am
content: The flux i have is over 10 years old, and doesnt act like flux...it just leaves a gooey mess all over the PCB.I didnt realise flux degraded like this?

author: tooki
author_rank: Super Contributor
timestamp: June 25, 2024, 06:51:22 am
content: Quote from: Faringdon on June 25, 2024, 05:55:47 amAnd it likely didn’t.What kind of flux? (Rosin, no-clean, etc) What form? (Liquid, paste, gel)Please provide the brand and part number of the flux.

author: John B
author_rank: Frequent Contributor
timestamp: June 25, 2024, 06:58:31 am
content: MG Chemicals 8341 no clean flux paste. The soldering joints should basically be submerged in flux, really helps to wet the pads and stop bridges.The no-clean part is a bit BS though, the board still needs to be cleaned afterwards. However it's better than the RA rosin stuff that becomes conductive!

author: Zero999
author_rank: Super Contributor
timestamp: June 25, 2024, 07:27:30 am
content: Post some pictures. There's not much point in a thread like this one, without them.I don't see why you need flux, unless your board or component are badly tarnished. I've recently soldered a smaller part than that, the 74HC1G66, on some plain old strip board, without using any flux or special equipment. I soldered it in between two tracks, with the middle pin (2) bent over the middle and soldered to another track, via a thin strand of copper wire.

author: Gyro
author_rank: Super Contributor
timestamp: June 25, 2024, 08:53:32 am
content: Quote from: Faringdon on June 25, 2024, 05:55:47 amWhy didn't you include fresh flux in the Farnell order that you placed at the weekend?

author: thm_w
author_rank: Super Contributor
timestamp: June 25, 2024, 09:15:38 pm
content: Quote from: John B on June 25, 2024, 06:58:31 amYou can usually get away with not cleaning it. Depends on how sensitive the circuitry is.Or are you just saying it makes a mess? Yeah would agree.

author: Zero999
author_rank: Super Contributor
timestamp: June 25, 2024, 09:47:45 pm
content: To clarify my previous post: "I don't use flux". It's not strictly true, since I use rosin cored solder, which contains enough to get the job done, without making a mess. I don't normally clean it, unless it's a sensitive, high impedance circuit, in which I use IPA, then tap water and soap (I know the soap part is controversial but is fine for most parts which can be washed, check the data sheet), then I rinse with deionised water.

author: tooki
author_rank: Super Contributor
timestamp: June 25, 2024, 10:01:20 pm
content: Quote from: John B on June 25, 2024, 06:58:31 amI’ll repeat what I’ve said many, many times before: no-clean fluxes are only no-clean when used in a way thatguaranteesit is sufficiently heated to both activateand then neutralizeit. This guarantee is provided with the flux core in solder wire, but for solder paste and all external flux (paste, gel, liquid) only reflow soldering in an oven guarantees this.The idea of course is that the flux residues are minimal (no-clean fluxes tend to have much lower solids content than traditional fluxes) and that those residues are safe to leave on the board. Consequently, no-clean fluxes are often much harder to clean, since easy cleaning isn’t a design goal when formulating it. It’s not “BS”, it’s just that one needs to understand that the naming is given within the context of industrial mass-production, and that hand soldering with it is a diiiiisssstant afterthoughtat mostin those flux formulations.As for RA flux: well, most people don’t need RA flux. Traditional rosin fluxes are mostly RMA, whose residues are almost always completely safe to leave on.

author: Faringdon
author_rank: Super Contributor
timestamp: July 01, 2024, 07:48:59 pm
content: Thanks, do you know where to get the flux used in 15:45 of this video.....because it makes his soldering effortlessly perfect....(as well as his shake free hand)..he uses some clear flux, which is quite pasty, do you know where to get it?....he says he buys stuff from BLT circuits, but i dont see it there.He also says use small conical tip..but i already did that and failed dismally.Also, howcome he doesnt burn up the solder resist like i do? That burned up, gunged up solder resist really impedes soldering....i find no flux deals with it.Also, he has the blue solder resist between each pin...thats usually impossible with a 0.5mm pitch chip...how does he manage to get that solder resist inbetween the pins like he does? No PCB manufacturer can do that?Also, thanks for the "MG Chemicals 8341" flux tip, ill look into that

author: tooki
author_rank: Super Contributor
timestamp: July 01, 2024, 08:01:03 pm
content: No, we can’t tell you where to get that flux because we have no idea what flux he’s using. He never specifies. Any decent flux should work fine for such an application.FYI, hand shaking goes WAY down when working under a microscope.

author: Gyro
author_rank: Super Contributor
timestamp: July 01, 2024, 08:21:50 pm
content: If you want liquid flux like that I recommend a flux pen, like MG chemicals - go for Rosin based and clean with IPA rather than 'no clean'. We used to use aerosol (plastic straw type) Electrolube SMFL too, it's cheaper per volume if you're doing a lot but can spread an make a real mess if you're not careful with the trigger...Pens:https://uk.farnell.com/search?st=flux+penbut cheaper from CPC and lower free delivery threshold [EDIT: Not next day though!]:https://cpc.farnell.com/c/tools-maintenance?st=flux+pen&showResults=trueAerosol:https://uk.farnell.com/electrolube/smfl200d/flux-bottle-200ml/dp/298311not available from CPC.For cleaning, Electrolube FLU FluxClene is more efficient than IPA, available in aerosol from both sites (RS too):https://uk.farnell.com/c/chemicals-adhesives/cleaners-degreasers?st=fluxcleneandhttps://cpc.farnell.com/c/tools-maintenance/cleaning-chemicals/workshop-cleaning-degreasers/flux-remover?st=fluxclene&showResults=true

author: Faringdon
author_rank: Super Contributor
timestamp: July 02, 2024, 06:44:14 pm
content: The video in #18 showed ace soldering, but it seems that the PCB used is very expensive...it has "burn-free" solder resist right up to all of the 0.5mm pitch pads.Also, i feel his PCB was ultra high power cured, so that the solder resist will not burn up....most PCBs are cheap and the solder resist isnt properly cured, so its awkward to get joints as easily as he shows.Rather than doing it his way, i did it the followoing way, which worked.....(no doubt the pro's just get a wee oven and do it in there, with a stencil , or whatever.How to solder a 16MSOP with ground pad (no ground pin).Use a Weller "LT 1", or "LT 1A" solder tip.This uses WP80 solder pencil and WD51 solder stationhttps://www.weller-tools.com/sites/default/files/products/documents/WEL_Poster_LT.pdfLT 1A:https://www.weller-tools.com/eu/gb/industrial-soldering/products/soldering-tips/lt-1aLT 1:https://www.weller-tools.com/eu/gb/industrial-soldering/products/soldering-tips/lt-1This tip is very pin pointed, but very short, so doesn't suffer thermal loss even though its very "sharp pointy".Make the footprint of the gnd padded 16MSOP conducive to hand soldering as such..Extend the PCB ground pad longwise (on the PCB), both ways, so it protrudes outside the chip body (with no solder resist on it).Then you can plonk two solder irons on each end of this at the same time, and guarantee soldering of theground pad.Also, make the 4 corner pads widen out upward, away from the chip. This makes soldering the end pins very easy.Tin the PCB footprint pads, but then braid them dry so there is only a micro thin film of tin on the pads.This way you can get the chip to sit very flat down on the pads.Clean all footprint with IPA before soldering. (and ESD brush)Wipe solder pen over pads after cleaning.Don't tin the ground pad on the chip....it will be too blobby and will make the chip not sit flat on the pads.Ensure the footprint pads extend widely outwards, and the solder resist opening should obviously also go with them.Then when you start soldering, you can start with the solder tip wide of the pin, but on the pin pad,and then you can push the tip point toward the pin and meet at the pin with <0.38mm solder.First pin to solder is an edge pin, just tack it down, ensuring the chip is flat.Then tack down the diagonal opposite edge pin.If you accidentally solder two pins together, then you may aswell, make them together all along, and that wayget a really good joint to the pads.Then clean any shorted pins with <=1mm braid edge pushed into the short. Or the braid_end layed along the shortedpins, then push the tip gently in and suck off the short._______---------________Please tell if the LM25148 (24VQFN) could be soldered in the same way as above,? and just as easily?....(it doesnt have "legs" as such)LM25148https://www.ti.com/lit/ds/symlink/lm25148.pdf?ts=1719940530190&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FLM25148%253Fbm-verify%253DAAQAAAAJ_____9JVxToUM_I04D9k3yOflsnnjfsnU0dSbc0ut9g3QSTU7_NHAC92mQERiv1f5Bx1wtHKio5gTDrSP23wpvXUgKbqjZQXCg-snL9juAUGQ2ubT0byaHfaxbgJg0HU-QF41Jc22uIjWMieemofTD676CuqWpTWfMxDhEy9WerttKZZUAzgrSxkU6wy5JfmfEkUKRKz8vHWIev8uddlolejUiipIod8owlkjJgEJsljZXxHdH5K4gy6NbN0NvSUlPHRF6_ZJAMH_ihvs8ZZtQvXaJIhzqUcrvEkiUDk6EXFE--PbzuvJPAAqpNasqxtBoU

author: thm_w
author_rank: Super Contributor
timestamp: July 02, 2024, 08:09:22 pm
content: You should use hot air or a hot plate/IR type heater to solder LM25148 (24VQFN).Either use solder paste or pre-wet the pads with an iron.Burn-free solder resist, lol.

author: Gyro
author_rank: Super Contributor
timestamp: July 02, 2024, 09:20:22 pm
content: Watching the guy in the #18 video soldering PQFP pins one at a time is just painful! Not only does it mean that he has to do the whole thing under a magnifier but requires an incredibly steady hand and is far too easy to miss a pin. Just watching him so easily clear a bridge between two pins, doesn't he realize that drag soldering is so much quicker, effectively using the same surface tension effect?

author: Zero999
author_rank: Super Contributor
timestamp: July 15, 2024, 09:45:22 pm
content: Here are some pictures of a tiny SOT353 device I soldered to a piece of strip board with the intention of using it on a solderless breadboard.Here's a data sheet for the device: 74HC1G66. I used the smaller package.https://www.farnell.com/datasheets/2342160.pdf