60/40 vs. 63/37 Solder
in [Basics]
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From: GregS on 15 Jul 2010 15:40 In article <7a307a68-f754-413e-8113-4b9d0ce7a236(a)c10g2000yqi.googlegroups.com>, George Herold <ggherold(a)gmail.com> wrote: >On Jul 15, 11:42=A0am, John Larkin ><jjlar...(a)highNOTlandTHIStechnologyPART.com> wrote: >> On 15 Jul 2010 08:04:55 GMT, John Doe <j...(a)usenetlove.invalid> wrote: >> >> >none given.now (Joe) wrote: >> >> >> Why are there these two very similar solders? =A0Is there any >> >> situation where one is better than the other? =A0 >> >> >Dunno, but... If you do detail work, try water-soluble flux >> >solder. You just wipe off the residue for a sparkling clean >> >circuit. >> >> And one that makes a great humidity sensor. >> >> John > > >Yeah, My prototype of a board with several high meg resistors (up to 1 >gig.) was put together by myself with old Kester "44" (rosin flux.) >Worked great. Production did a few with their favorite water based >flux... No good! Now I have to convince them to go back to the old >standard. The new ROHS fluxes seem to be even worse. I measured a >few meg ohms between pads that had been 'cleaned'.... NOT. > I had a lot of problems with high Z circuitry. Got under the pads. Some boards I had to clean/dry 10 times. In the interim, some of the cleaner I used got into some caps and started their own circuit mess. greg
From: David Eather on 15 Jul 2010 15:49 On 15/07/2010 5:54 PM, Joe wrote: > Why are there these two very similar solders? Is there any situation > where one is better than the other? > > I understand the eutectic nature of 63/37, and I wonder if/when 60/40 > might ever be better to use. > > --- Joe PeterD mentioned the significant parameter in his post. because it is a eutectic mixture 63/37 does not have "much of a plastic state" this means it is more sensitive to movement in the joint while the solder is cooling - if the connections are unstable it forms more dry joints. This was important with point to point wiring but is now less important with PCBs. You can normally use either solder for any job but the "old timers" experience would suggest 60/40 is the better choice for wiring front panels, flying leads and the like and 63/37 would be better for heat sensitive components. (for the obnoxious who will claim there is no difference - please note that those doing the jobs *did* find a difference and thought it significant enough to bother about)
From: Dave Platt on 15 Jul 2010 16:06 >Why are there these two very similar solders? Is there any situation >where one is better than the other? > >I understand the eutectic nature of 63/37, and I wonder if/when 60/40 >might ever be better to use. My understanding is that 60/40 has somewhat better wetting properties than 63/37, at least with some contact materials. Some people prefer it for that reason. 63/37 makes a sharp transition between liquid state and solid state at a single, well-defined temperature. 60/40 goes through a transition between these two states over a significant range of temperature - in between the fully-solid and fully-liquid states it can have a somewhat mushy texture. Some people feel that 60/40 brings with it a somewhat higher risk of creating a "cold" solder joint (inadequate fusion with the contact surfaces) if the joint is moved or stress while the solder is dropping through its mushy-state temperature region. -- Dave Platt <dplatt(a)radagast.org> AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads!
From: William Sommerwerck on 15 Jul 2010 16:19 > Because it is a eutectic mixture, 63/37 does not have "much > of a plastic state". This means it is more [sic] sensitive to > movement in the joint while the solder is cooling -- if the > connections are unstable it forms more [sic] dry joints. I don't what you meant to say, but what you did say is backwards. Eutectic solder is less likely to produce a dry or crystallized joint.
From: Jim Yanik on 15 Jul 2010 17:35
"William Sommerwerck" <grizzledgeezer(a)comcast.net> wrote in news:i1nqh7$7qt$1(a)news.eternal-september.org: >> Because it is a eutectic mixture, 63/37 does not have "much >> of a plastic state". This means it is more [sic] sensitive to >> movement in the joint while the solder is cooling -- if the >> connections are unstable it forms more [sic] dry joints. > > I don't what you meant to say, but what you did say is backwards. > Eutectic solder is less likely to produce a dry or crystallized joint. > > > I agree; the eutectic joint solidifies faster and thus less likely to move while the solder is still "plastic". -- Jim Yanik jyanik at localnet dot com |