What do you mean by less heat? A lower temperature? A shorter time?
Both? All that any of these means is that the conditions to form the
optimal joint no longer exist. Please do not forget that the formation
of a solder joint is a chemical reaction whereby (say) tin and copper
react to form intermetallic compounds. The optimal conditions require a
given combination of temperature of the tin AND copper over a given
time. Reduce either, and the joint is no longer optimal. The functions
of the flux are numerous, but its acidic activity is mainly to reduce
metallic oxides so that the tin and the copper are clean enough for the
metallurgical reaction to take place. This oxide reduction occurs mainly
during the preheating phase, before the copper reaches soldering
temperature, so the type or quantity of flux has relatively little
influence on the speed of the reaction, although a highly reactive flux,
such as a water-soluble organic hydrochloride type, may just reduce the
overall time by a tiny fraction of a second.
"In a quick poll of some of my fellow old-timers who worked on military
stuff all agreed." I guess your "old-timers" must be quite old, from the
days when soldering was a "seat-of-the-pants" art and not a science,
like it is today. Any person mixing two flux types for a military
application would be shot down in flames by the inspectors from the UK
Ministry of Defence and, presumably, the US DoD or sent out to Iraq to
make sure Saddam's famous WMD would fail from faulty electronics. What
you are proposing is an antithesis of reliability. Please quote me a
single MIL Spec since Julius Caesar's days that said, "Thou art
permitted to make whatever mixture of fluxes you please." or words to
that effect. In all my 50 years of experience in this industry, I have
never, ever, seen it done: the only times I've seen liquid flux used for
hand soldering, it was with coreless, solid solder wire.
In the very unlikely event that there is insufficient flux in a cored
solder wire, then I very seriously suggest that, before you jeopardise
the reliability of your products, you consult the manufacturer of the
wire and have it exchanged for one with a slightly greater percentage of
flux, or you change suppliers.
Brian
Phil Nutting wrote:
> Brian,
>
> I can't argue with your statements. I can only speak from personal experience (including a test last night) that adding the liquid flux makes a much better solder joint with less heat applied to the joint. In a quick poll of some of my fellow old-timers who worked on military stuff all agreed.
>
> Gee, what would Moonman say to this one?
>
> Phil
>
> -----Original Message-----
> From: Brian Ellis [mailto:[log in to unmask]]
> Sent: Thursday, February 27, 2003 3:17 AM
> To: TechNet E-Mail Forum.; Phil Nutting
> Subject: Re: [TN] Adding liquid flux when hand soldering
>
>
> If you are using cored solder, you should never add flux. Because:
> a) liquid flux will spread beyond where you need it and add to contamination
> b) the chances are the two fluxes will be incompatible with each other
> c) there is a distinct possibility the residues will be impossible to
> clean off correctly or, if they are both "no-clean", they will form a
> dangerous flux porridge which could be ionically incompatible with
> reliability
> d) you are insulting the wire manufacturer who has determined the
> quantity and type of flux, through scientific lab tests, to optimise
> what you are trying to do.
>
> IOW, you will cause far more harm than good.
>
> Brian
>
> Phil Nutting wrote:
>
>>Is it a common practice to add liquid flux when soldering by hand or do you rely on the flux core of the solder? My 30+ years says add the liquid flux for the best solder joint, but that was back when I was involved with rocket science.
>>
>>Phil Nutting
>>
>>---------------------------------------------------
>>Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
>>To unsubscribe, send a message to [log in to unmask] with following text in
>>the BODY (NOT the subject field): SIGNOFF Technet
>>To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
>>To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
>>Search the archives of previous posts at: http://listserv.ipc.org/archives
>>Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
>>information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
>>-----------------------------------------------------
>>
>>
>>
>>
>>
>
>
> ---------------------------------------------------
> Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
> To unsubscribe, send a message to [log in to unmask] with following text in
> the BODY (NOT the subject field): SIGNOFF Technet
> To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
> To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
> Search the archives of previous posts at: http://listserv.ipc.org/archives
> Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
> information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
> -----------------------------------------------------
>
>
>
>
>
---------------------------------------------------
Technet Mail List provided as a free service by IPC using LISTSERV 1.8e
To unsubscribe, send a message to [log in to unmask] with following text in
the BODY (NOT the subject field): SIGNOFF Technet
To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)
To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest
Search the archives of previous posts at: http://listserv.ipc.org/archives
Please visit IPC web site http://www.ipc.org/html/forum.htm for additional
information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315
-----------------------------------------------------
|
