EEVBlog SMD soldering tutorial(s) - need exact references to order stuff... - Page 1
Forum section: electronics / general

author: Vince
author_rank: Super Contributor
timestamp: April 14, 2013, 10:04:06 pm
content: Hi there,Always sticked to through hole stuff in my projects so far, but the marvelous tutorials from Dave on SMD soldering somehow made me confident that it was possible, and even simple at that !And well, it turns out I just have a need/opportunity to pioneer SMD soldering, as I am trying to fix a defective Tek TDS 300 series CRO I just got on Ebay for just 60 Euros ! The upper 4 rotary knobs of the front panel do funny business and make the scope impossible to operate. I am suspecting the two surface mount 74HC4051 analog multiplexers on the front panel board, and would like to try and replace them to see what that does... but my solder wick and solder are not suitable, hopeless, way too coarse. So while I am ordering the chips form Farnell, I need to also get some appropriate solder wick and solder, so as to hopefully be as successful as Dave in his videos but the question is...WHATto order !?Farnell lists TONS of solder wick and solder... and I don't want to order one of each and test them all to see which one is best !So Dave if you are reading this, may I ask you to post the exact reference (brand and model) of solder wick and solder you use, so I/we can hopefully find it in Farnell's catalog (only major/serious supplier we have access to in France, as hobbyists), and if not... at least give us the most important specs that do matter for the quality of the job ?From what I can recollect, you said that the solder must be of the old leaded type, because the ROHS stuff is a bit of a pain, and that it must be as small as possible, you mentioned 0,4mm or about, IIRC. It must also have built-in flux, right ? (don't even know if flux-less solder even exists ?).For the solder wick, it seems you use a bare copper, non-tined model. But what is its width, and how many wires does it have (how "fine" is it, IOW).I have had only bad luck with my 3mm wide tined solder wick, despite it cost me a fortune. I think the wires in it are way too big in diameter, but don't know what diameter would be small enough to efficiently suck solder from tiny SMD pads... your solder wick in your videos appear to do such a fantastic and quick job, I dream of having such a marvel in my drawers !Flux pen: brand and model ?I think that's all that's needed... oh yeah, and a pair of fine tweezers, but I guess any model will doThanks in advance for your help !

author: free_electron
author_rank: Super Contributor
timestamp: April 17, 2013, 02:58:31 pm
content: It's most likely dirty encoders. Flush them out with a good contact cleaner.

author: Vince
author_rank: Super Contributor
timestamp: April 17, 2013, 05:48:20 pm
content: Yeah that did the trick recently with my 40 year old function generator the other day, so tried that on the Tek scope, but alas no luck, didn't change a thing. They are very good quality ceramic items unlike the crappy pots in the antic function gen. I checked voltages on both the outputs. Tthey have two offset outputs each (offset by a quarter turn or so), the schematics label them as differential outputs, not sure how it all works... but outputs can smoothly swing from rail to rail no problem, as I turn the know. There are also a couple buttons/switches that don't work even when I short their pins, despite the other buttons of the matrix arrangement, which use the same row and column, work just fine ! this is totally weird... I would kill to know what's going on... maybe I should send it to Dave as a challenge ! LOL Would cost me fortune to ship it so far away so...One thing that maybe could explain the weird analog rotary switches behavior could be maybe, if the analog multiplexer aren't faulty (I shall soon see), would be well... the two ADC inputs of the MCU (Motorola 68000 series) they feed, might be faulty. If this is it then it's a lost cause, as I might be still be able (haven't checked Farnell yet for that) to buy the Motorola MCU these days, but I have no way to read the program from the MCU, never mind the facility to burn it in a new chip. So I would have to call it scrap....There is one thing that I could investigate that might (?) eventually give me new pointers : the scope REFUSE to power up if the front panel flat cable is connected/attached to the main board. It would power up but power off instantly. However if I disconnect the flat cable it powers up just fine, then I quickly reconnect the cable/front panel and it's happy. The (soft) power switch transits via the main board and front panel, but is untouched by any of them. So it's got to be the PSU itself that's upset by the front panel, in some way ! But there is no short otherwise why would it work if I plug it just after power up... really this whole front panel bug makes no sense to me, I would kill to know what's going on.. surely that would be an interesting lesson !As for solder wick and solder on Farnel, I think I narrowed ti down to what Dave might be using. Some "multicore branded" Loctite stuff. Now I just need a reply for the brand of pflux pen to get.. failing a reply I will just get the first in the list, since they are all the same price, 7.50 Euros.

author: nanofrog
author_rank: Super Contributor
timestamp: April 17, 2013, 08:26:52 pm
content: Generally, I'd go for either a 63/37 or 60/40 alloy, rosin core, in ~ 25AWG (0.20"/0.508mm) diameter max.; 28AWG = 0.40mmFlux, I'm partial to Rosin, followed by No-Clean (wouldn't recommend water clean)Wick, I'd stick to 1.5mm max, and get a spool of 0.8mm as a starting point, and go from there.Take a look at the following for some specific P/N's:Kester 44 (0.20", 63/37, Rosin core)http://uk.farnell.com/kester-solder/24-6337-0010/solder-wire-63-37-sn-pb-183-c-1lb/dp/7798120Kester 44 (0.16", 63/37, Rosin core)http://uk.farnell.com/kester-solder/24-6337-8806/solder-63-37-0-4mm/dp/1610447Circuit Works Rosin Flux penhttp://uk.farnell.com/circuitworks/cw8100/dispensing-pen-flux-no-clean-9g/dp/130692Solder Wick (0.8mm width)http://uk.farnell.com/multicore-loctite/ncoo-0-8mm-1-5m/braid-desoldering-1-5m-0-8mm/dp/1115541Solder Wick (1.5mm width)http://uk.farnell.com/multicore-solder/nc-aa/braid-desoldering-1-5m-1-5mm/dp/252487They have other selections, so you may want to have a closer look. Wick can also be had in larger spools, which can be less expensive in the long run.As per brands, Kester is more commonly found in the US, so I'm more accustomed to using that than Multicore (owned by Henkel), but either would be good stuff. So is AIM (American Iron & Metals if you can find it), and may be less expensive than either. For flux, I prefer Kester 186-18, but it has to be purchased in large containers (1 gal = smallest container they sell, so not the most DIY friendly in terms of cost). MG Chemicals Rosin flux is good too (higher solids %, so it's a bit messier; sold in much smaller containers, such as 125ml bottle and quart). For wick, I'm partial to Chemtronics and MG Chemicals.

author: Vince
author_rank: Super Contributor
timestamp: April 17, 2013, 08:43:22 pm
content: Thanks for the info and pointers Nanofrogs, much appreciated !Yeah I am hobbyist and don't envision having to go into mass soldering of SMD components any time, so I need the stuff in small quantities

author: nanofrog
author_rank: Super Contributor
timestamp: April 17, 2013, 09:10:10 pm
content: Quote from: Vince on April 17, 2013, 08:43:22 pmGlad it helps.I took a chance on an eBay seller that makes smaller containers of Kester 186 (higher solids than 186-18 <36% solids vs. 18%, but still lower than MG Chemicals which is 50% solids>). So far, so good thus far. Perhaps that's a possibility, but given the chance for a fake, don't get carried away if you try this route (I only ordered a single 2.5oz bottle @ $6.25USD, including shipping). Gallon of it goes for ~$63 - 65 or so, and Kester states a shelf life of 3 years (I'd probably be lucky to use that much in a lifetime).Found a couple on eBay.fr, but I've no idea if either is really what is claimed or not.0.5 oz (15cc):http://www.ebay.fr/itm/Kester-186-No-Clean-Flux-Electronic-Grade-No-Clean-Flux-DIY-Solar-Panels-/110861350623?pt=LH_DefaultDomain_0&hash=item19cfd9f6df2 oz (60cc):http://www.ebay.fr/itm/KESTER-186-RMA-FLUX-for-SMT-BGA-Rework-No-Clean-60cc-/110852193367?pt=LH_DefaultDomain_0&hash=item19cf4e3c57

author: Vince
author_rank: Super Contributor
timestamp: April 17, 2013, 09:44:01 pm
content: No way I am going to trust Ebay for sourcing professional stuff of any kind, electronics or else, don't want to take my chances. So I think I will prefer a flux pen like Dave uses. The Circuit works one you mentioned so happens to be the one I decided to pick ! What a coincidence, guess I was lucky in my then non-informed choice. I prefer the pen type anyway, find it more practical, and seemed to work just fine in Dave's hands, so can't be bad I guess.Ok I guess I am ready to order now, 75 Euros all in, for about a couple 0.50 Euro chips !Luckily all that solder, solder wick and flux pen is good stuff and will last me a loooooong time, given it won't get much use, in absolute terms.So I see it as an investment... and these 74HCT chops were just an excuse to start gathering some basic and indispensable soldering products...Hell I guess I can't complain : at least the pitch is quite large (in SMD terms...) at 1,27mm, so I don't have to spend a fortune in a microscope...

author: nanofrog
author_rank: Super Contributor
timestamp: April 18, 2013, 04:25:23 am
content: Quote from: Vince on April 17, 2013, 09:44:01 pmQuite understandable. I don't usually like buying from eBay either, but if the feedback looks good and I decide to take a chance (rare), I keep the risk low (under $10USD). I decided to take the risk for the Kester 186 as I've gotten excellent results from it, and would like to stick with it if possible (MG Chemicals otherwise).My reasoning behind buying it in a larger container then adding it to a dispenser (bottle w/ needle or to a refillable pen), is it's cheaper and it offers me options (I find a bottle w/ needle a bit better for drag soldering and tinning wire, and a pen for pretty much anything else).FWIW,Chemtronics CW7000 Refillable pens (2 pack):http://www.chemtronics.com/products/product.asp?r=1&m=2&id=537Farnell carries them if you're interested...http://uk.farnell.com/circuitworks/cw7000/flux-accessory-ba-dispensg-pen/dp/1818307?Ntt=CW7000Now say you find a small bottle of flux (say 100 or 125ml), for ~15GBP, and you're under 3GBP per 10ml (~ what you'd get in a ready-made pen), and it will get less expensive over time, as the pens are refillable rather than disposable.Bit more effort, but at ~7 - 8GBP per disposable pen, the savings add up fairly quickly.= More funds can be spent on parts per order.Quote from: Vince on April 17, 2013, 09:44:01 pmAh, minimum order amounts.