really bad SMD solder practice kit - Page 1
Forum section: electronics / general

author: graybeard
author_rank: Frequent Contributor
timestamp: March 03, 2019, 06:32:07 am
content: I recently decided to start building circuits at home again. I did when I was a kid and did so until into grad school. However at work I design ICs, systems, PCBs, top level software, but I never do the work building or coding it myself and I miss it.I decided to buy some surface mount solder practice kits from eBay, because I have never soldered SMD parts myself and for the most part they are the only thing available now, so I need to learn how to do them.I bought three solder practice kits from eBay about a month ago. A few days after I purchased them eBAY pulled the listing without explanation, but sent me a message saying that mine had been shipped.So they arrived on Wednesday and I went to try and use them this evening. When I did I discovered that some of the parts they sent me were not compatible with the footprint on the board, and parts were missing.You can see that the board is labeled at the top right for an SOP16 part (ehich was sent), however the footprint is for a SOP14 part. If this was the only issue I would be fine, it is for soldering practice, not an operating circuit.However none of the kits had an SSOP28 device, and in stead of 1206 resistors had this strange tiny 8 terminal device that is incompatible with any of the footprints.What is this tine 8-terminal package? The pins seem to be open.I requested a refund from the seller.p.s. I know my soldering sucks . . . thats why I bought the kit . . . I have not really done much for 30 years.

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 03, 2019, 07:00:09 am
content: Quote from: graybeard on March 03, 2019, 06:32:07 amresistor array, 4 of them. measure 2Kohm on each top and bottom pin pair. of course not connected if you measure to adjacent pin. btw if its for smd training kit, what components you have doesnt matter, what matter is how is your soldering skill. use suitable solder flux and it will become magic.Quote from: graybeard on March 03, 2019, 06:32:07 ampoor seller.

author: forrestc
author_rank: Unknown
timestamp: March 03, 2019, 07:46:52 am
content: Quote from: Mechatrommer on March 03, 2019, 07:00:09 amSecond on the flux. SMD soldering pretty much requires flux. Not as much as Louis Rossman uses on his videos, but some.We buy production grade in production quantities so what I'm familiar with isn't available in mere mortal quantities, although I will say that the kester flux pens are popular and available.

author: graybeard
author_rank: Frequent Contributor
timestamp: March 03, 2019, 08:52:16 am
content: They are arrays of for 2K resistors.I have various sizes of solder but so far I am liking the 22 mil Multicore. I have not tried the 15 mil Alpha yet.I have liquid RMA and RA flux in small dispensers. I glue a small piece of circuit board to the bottom so they don't tip over. So far I have just used the RMA flux (Kester).I'm still playing with tip size and temperature.I am using my 40 year old Panavise with a new base.I have tried several different tweezers and some blunt tip stainless ones seem to be the best I have. I noticed that some people use the ceramic tweezers, but I don't have any of those. Are they better at not conducting heat away from the part?

author: forrestc
author_rank: Unknown
timestamp: March 03, 2019, 09:34:59 am
content: Quote from: graybeard on March 03, 2019, 08:52:16 amI prefer to use a orangewood stick to hold the part in place, but many do use tweezers.My method for chip resistors when using a single iron typically involves tinning one pad on the board, adding some flux, positioning the part such that it is resting in the correct position and then holding it in place with the stick while I re-heat the tinned pad. When the pad heats up, the flux will clean everything up, the solder will melt, and the chip will end up pushed onto the board, at which point I remove the iron, then the orangewood stick once the joint cools (a second or so). I'll then solder the other end with the iron while feeding wire. I know others use tweezers. If you're quick the other end won't melt.BTW, for small parts .032 wire can be used, but ~.016 is better. 63/37 or 60/40 if you're doing the tin/lead thing.

author: Cnoob
author_rank: Regular Contributor
timestamp: March 03, 2019, 10:02:06 am
content: I have a couple of smd kits off ebay although I'm still mostly using through hole.I do have equipment and stuff to do smd but haven't taken it on seriously yet.I'm impressed with the kits for how cheap they are and what they contain. (haven't built one up yet, but how hard could it be?)

author: Twoflower
author_rank: Frequent Contributor
timestamp: March 03, 2019, 10:19:32 am
content: Don't use too small tip-sizes. They tend to have problems keeping the temperature. I use a normal chisel shaped tip. I think about 1.5mm width. Even with multicore solder: Use some additional flux.Looking at your picture: Use less solder. About half you put at the R42 pad. Add just a little bit. The surface tension will pull the solder to the device in the second step.Have you checked some videos how SMD soldering should work? It helped me a lot. You might have a look to this thread:What's your favorite "how to solder" video to share with friends/noobs that ask?

author: ar__systems
author_rank: Frequent Contributor
timestamp: March 03, 2019, 03:55:00 pm
content: It is a training kit. Who cares if the parts don't match exactly. If you pay postage I can send you tons of unused PCBs and some old partsThe most important tool for high quality soldering is a stereo microscope. They are not that expensive. Once I got it I solder everything under it.

author: graybeard
author_rank: Frequent Contributor
timestamp: March 03, 2019, 05:11:13 pm
content: I have a very nice Bausch & Lomb stereo zoom. I was already planing to try using that next for soldering. I have been using it to inspect my work.

author: jmelson
author_rank: Super Contributor
timestamp: March 03, 2019, 07:48:23 pm
content: Quote from: graybeard on March 03, 2019, 05:11:13 pmI don't use the microscope for 0805 passives, but for anything smaller, and all ICs I do use it, generally on the lowest magnification.Makes things SO much easier to do right.Bent nose long tweezers are also a big help, and a temperature-controlled soldering iron with changeable tips.Jon

author: Mechatrommer
author_rank: Super Contributor
timestamp: March 03, 2019, 11:00:43 pm
content: if you have good eyes, microscope is not really necessary, esp if you have tight budget. my eyes seem to deteriorate but my single magnification lens that i scrapped from a helping hand does a better job. i want a stereo microsope but the price is a bit prohibitive. i know there are amscope china brand, but they are not my taste and they will occupy my bench more when in use, and working distance of 10cm is not that fantastic i think for the microscope size. i want boom (articulated arm) type, where i can pivot it far away from bench where there are spaces for it, but the price is a bit prohibitive. so i'll stick with my single cheapy lens while i still can with modded 3d printed lens and leds holder + magnetic stand arm originally for my dial indicator.