From: harveytwyman@my-deja.com Newsgroups: comp.arch.fpga Subject: Hand Soldering a PQ208 - It looks tough to do Date: Wed, 20 Dec 2000 10:32:37 GMT Organization: Deja.com Lines: 27 Message-ID: <91q1s5$mag$1@nnrp1.deja.com> NNTP-Posting-Host: 194.82.103.45 X-Article-Creation-Date: Wed Dec 20 10:32:37 2000 GMT X-Http-User-Agent: Mozilla/4.0 (compatible; MSIE 5.5; Windows 95) X-Http-Proxy: 1.0 wwwcache1.ukc.ac.uk:3128 (Squid/2.2.STABLE3), 1.0 fides.ulcc.wwwcache.ja.net:8080 (Squid/2.2.STABLE5-hno.20000202), 1.0 x72.deja.com:80 (Squid/1.1.22) for client 129.12.50.213, 129.12.1.65, 194.82.103.45 X-MyDeja-Info: XMYDJUIDharveytwyman Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news.nextra.ch!newsfeed1.online.no!nextra.com!news.tele.dk!128.230.129.106!news.maxwell.syr.edu!nntp2.deja.com!nnrp1.deja.com!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:3428 Being involved with student projects, the ability to handle the latest SMT devices has been essential. I've developed techniques over the last few years that are successful for beginners as they only require simple hand tools. My Web Page below describes these techniques in detail: http://www.Makaton-Signs.org.uk/PCB-Techniques ___________________________________________ ===| |=== ===| H A R V E Y T W Y M A N |=== ===| ----------------------------------------- |=== ===| Department of Electronics, |=== ===| University of Kent. |=== ===| Canterbury. U.K. |=== ===| ----------------------------------------- |=== ===| ABOUT ME: http://www.Twyman.org.uk/CV.htm |=== ===| ----------------------------------------- |=== ===| EMAIL ME: H.E.Twyman@ukc.ac.uk |=== ===|___________________________________________|=== Sent via Deja.com http://www.deja.com/ ###### From: "Steve W." Newsgroups: comp.arch.fpga References: <91q1s5$mag$1@nnrp1.deja.com> Subject: Re: Hand Soldering a PQ208 - It looks tough to do Lines: 82 X-Newsreader: Microsoft Outlook Express 4.72.3110.1 X-MimeOLE: Produced By Microsoft MimeOLE V4.72.3110.3 Message-ID: <_xf06.7005$bv3.71088@newscontent-01.sprint.ca> Date: Wed, 20 Dec 2000 23:22:27 -0500 NNTP-Posting-Host: 149.99.141.254 X-Complaints-To: abuse@sprint.ca X-Trace: newscontent-01.sprint.ca 977372410 149.99.141.254 (Wed, 20 Dec 2000 23:20:10 EST) NNTP-Posting-Date: Wed, 20 Dec 2000 23:20:10 EST Organization: Sprint Canada Inc. Path: chonsp.franklin.ch!pfaff.ethz.ch!news-zh.switch.ch!news.ifi.unizh.ch!news.imp.ch!news-spur1.maxwell.syr.edu!news.maxwell.syr.edu!east1.newsfeed.sprint-canada.net!HME1-2.newsfeed.sprint.ca!newscontent-01.sprint.ca.POSTED!not-for-mail Xref: chonsp.franklin.ch comp.arch.fpga:3498 Good site Harvey. A couple of comments though... 1) If people are after this sort of info. I'd recommed the NG sci.electronics.design, which is probably more suitable than an fpga site. 2) Never use sharp tweezers? I've been working for years in the industry and it was because of SMT that people went to sharp tweezers. You don't stab the devices with the sharp points but you need the narrow tips improved precision to grab those little parts. Are the tweezers you're talking about smooth on the gripping surface or ribbed? 3) The use of 2% silver solder is not that common for reel type solder and I certainly I have seen lots of SMT done without it. What is the reason for it? 4) I think tin-plating is generally good and I'd recommend it. I guess it depends on what kind of junk you let get in the solution and whether you have control of the source. You could have a virgin bottle and a used bottle so that you don't degrade the whole lot at once. Typically I find that the solution becomes very ineffective but doesn't contaminate. I've gone from old, used solution that took 20 minutes to plate to new, fresh solution that plated instantaneously when dropped in the solution. 5) With tin plating you can typically place the part flat and then solder. However, if you don't do plating you can follow the technique you described. However, I don't quite agree with your interpretation of the commercial pcb vendors overcoming the problem. They do solve the problem but typically the boards they build are not hand soldered and thus not subject to the sinking problem of one pin being soldered before the other. In commercial operation you typically use solder paste and go through an IR-relflow oven. If not, you glue the part down and go through a molten wave-solder machine. The HASL finish (hot air solder leveling) is to make sure that the large fine pitch multi-pin devices sit flat before they are soldered. As I've moved into very big and even finer pitch BGA devices HASL is sometimes found to be not flat enough and hence the move to gold electro-plate finishes (but HASL keeps improving). 5) You say that capacitors have no identification marks at all. Well that isn't always true and there many smt caps I've used with codes. However, they are not as easy to read as the resistors or the old through-hole caps. They use a cryptic alpha numeric code. The first letter is the vendor (k= kemet) and then a alpha-numeric pair that requires a decoding table to figure out the value. If I find a table on the kemet site (or other) I'll post a link. Steve harveytwyman@my-deja.com wrote in message <91q1s5$mag$1@nnrp1.deja.com>... >Being involved with student projects, the ability to handle the latest >SMT devices has been essential. > >I've developed techniques over the last few years that are successful >for beginners as they only require simple hand tools. > >My Web Page below describes these techniques in detail: > >http://www.Makaton-Signs.org.uk/PCB-Techniques > > ___________________________________________ >===| |=== >===| H A R V E Y T W Y M A N |=== >===| ----------------------------------------- |=== >===| Department of Electronics, |=== >===| University of Kent. |=== >===| Canterbury. U.K. |=== >===| ----------------------------------------- |=== >===| ABOUT ME: http://www.Twyman.org.uk/CV.htm |=== >===| ----------------------------------------- |=== >===| EMAIL ME: H.E.Twyman@ukc.ac.uk |=== >===|___________________________________________|=== > > > >Sent via Deja.com >http://www.deja.com/