I think I figured it out enough to make sense of it. The 1.5 ohms will likely be the normal state and if a short occurs the resistance will quickly rise to the 10 ohms and trip the PTC fuse. That works for me. The reason I was worried a little is that the resistors I use in the circuit range from 5.1 to 10 ohms and that could have caused me some re-design issues.
Thanks,
Dave
On 11/7/2019 6:46 PM, Dave wrote:

In reference to the part number 1206L010/60 (second one down in top list), I have a question.

Resistance R (min) = 1.5 ohms
Resistance R (1max) = 10 ohms

R min = Minimum resistance of device in initial (un-soldered) state.
Rtyp = No spec given.
R 1max =? Maximum resistance of device at 20°C measured one hour after tripping or reflow soldering of 260°C for 20 sec.

Question: If I were to figure in the resistance for the PTC fuse as part of my equation for selecting the correct resitors further down the circuit...What number in ohms should I use? In other words, when the circuit is in normal operation, what will the resistance of the PTC actually be?
Thanks,
Dave

In reference to the part number 1206L010/60 (second one down in top list), I have a question.

Resistance R (min) = 1.5 ohms
Resistance R (1max) = 10 ohms

R min = Minimum resistance of device in initial (un-soldered) state.
Rtyp = No spec given.
R 1max =? Maximum resistance of device at 20°C measured one hour after tripping or reflow soldering of 260°C for 20 sec.

Question: If I were to figure in the resistance for the PTC fuse as part of my equation for selecting the correct resitors further down the circuit...What number in ohms should I use? In other words, when the circuit is in normal operation, what will the resistance of the PTC actually be?
Thanks,
Dave

I've tried thinning old dry paste with denatured alcohol and the result was that the components popped off the board like popcorn as soon as I heated it up.

ST

On Thu, Nov 7, 2019 at 3:35 AM Charlie Hansen <n0tt1@...> wrote:

Thanks Donald....

So, in a way it's like paint...solvent evaporates and the solids settle
out.

I just wonder what chemical the "medium" is....and if more of the same
were added and mixed would that prolong its life even more?? Now, that's
with evaporation....oxidation is quite another issue.? Any thoughts on
that?

Charlie


On Tue, 5 Nov 2019 18:51:04 -0500 "Donald H Locker"
<dhlocker@...> writes:
> The medium carrying the solids changes viscosity as it ages and
> evaporates and oxidises and/or reduces); the solder balls settle as
>
> gravity exerts its ever-present force; the flux reacts with the
> vehicle
> and solder reducing the fluxing potency and the vehicle viscosity
> and
> solder wettability. There are probably other effects, but those are
> the
> big ones that I've read about.
>
> Donald.
> --
> *Plain Text* email -- it's an accessibility issue
> () no proprietary attachments; no html mail
> /\ <>
>
> On 2019-11-05 6:30 p.m., Charlie Hansen wrote:
> > "> Be aware that the rated shelf life is anywhere from 6 months to
> a
> >> year.? It lasts longer if you keep it refrigerated, especially
> after
> >> breaking the seal."
> >
> > Guys, there's something I always wanted to know about that shelf
> > life....what the heck causes the stuff to go bad?
> >
> > Charlie
> >
> >
> > On Tue, 05 Nov 2019 14:51:58 -0700 "Dwayne Reid"
> <dwayner@...>
> > writes:
> >> Hi there.
> >>
> >> We have been purchasing 63/37 solder paste from Chip Quik? -
> both
> >> direct and via Digikey.? It's available in both syringe and jar
> >> form.
> >>
> >> Be aware that the rated shelf life is anywhere from 6 months to
> a
> >> year.? It lasts longer if you keep it refrigerated, especially
> after
> >>
> >> breaking the seal.
> >>
> >> We normally purchase the Water Soluble flux version - we then
> just
> >> wash the boards under running hot water and blow dry with
> compressed
> >>
> >> air.? This works especially well for the small prototype board
> runs
> >> that we do.
> >>
> >> dwayne
> >>
> >>
> >> At 10:39 AM 11/5/2019, Dave wrote:
> >>> I have plenty of regular solder, and plenty of flux, now I need
> to
> >>
> >>> buy some solder paste for smd stuff. Any recommendations? I
> would
> >>> like some in a jar and also a syringe just to have both. Is
> >> no-clean
> >>> solder better? Also, I just want tin/lead solder if it is still
> >> available.
> >>>
> >>> Thanks,
> >>>
> >>> Dave
> >>
> >>
>
>
>
>

?

The MSDS for the ChipQuick solder past lists Terpineol.

?

Mike N.

?

From: [email protected] [mailto:[email protected]] On Behalf Of stefan_trethan
Sent: Wednesday, November 6, 2019 10:16 PM
To: [email protected]
Subject: Re: [homebrewpcbs] Solder paste recommendations

?

I've tried thinning old dry paste with denatured alcohol and the result was that the components popped off the board like popcorn as soon as I heated it up.

?

ST

?

On Thu, Nov 7, 2019 at 3:35 AM Charlie Hansen <n0tt1@...> wrote:

Thanks Donald....

So, in a way it's like paint...solvent evaporates and the solids settle
out.

I just wonder what chemical the "medium" is....and if more of the same
were added and mixed would that prolong its life even more?? Now, that's
with evaporation....oxidation is quite another issue.? Any thoughts on
that?

Charlie


On Tue, 5 Nov 2019 18:51:04 -0500 "Donald H Locker"
<dhlocker@...> writes:
> The medium carrying the solids changes viscosity as it ages and
> evaporates and oxidises and/or reduces); the solder balls settle as
>
> gravity exerts its ever-present force; the flux reacts with the
> vehicle
> and solder reducing the fluxing potency and the vehicle viscosity
> and
> solder wettability. There are probably other effects, but those are
> the
> big ones that I've read about.
>
> Donald.
> --
> *Plain Text* email -- it's an accessibility issue
> () no proprietary attachments; no html mail
> /\ <>
>
> On 2019-11-05 6:30 p.m., Charlie Hansen wrote:
> > "> Be aware that the rated shelf life is anywhere from 6 months to
> a
> >> year.? It lasts longer if you keep it refrigerated, especially
> after
> >> breaking the seal."
> >
> > Guys, there's something I always wanted to know about that shelf
> > life....what the heck causes the stuff to go bad?
> >
> > Charlie
> >
> >
> > On Tue, 05 Nov 2019 14:51:58 -0700 "Dwayne Reid"
> <dwayner@...>
> > writes:
> >> Hi there.
> >>
> >> We have been purchasing 63/37 solder paste from Chip Quik? -
> both
> >> direct and via Digikey.? It's available in both syringe and jar
> >> form.
> >>
> >> Be aware that the rated shelf life is anywhere from 6 months to
> a
> >> year.? It lasts longer if you keep it refrigerated, especially
> after
> >>
> >> breaking the seal.
> >>
> >> We normally purchase the Water Soluble flux version - we then
> just
> >> wash the boards under running hot water and blow dry with
> compressed
> >>
> >> air.? This works especially well for the small prototype board
> runs
> >> that we do.
> >>
> >> dwayne
> >>
> >>
> >> At 10:39 AM 11/5/2019, Dave wrote:
> >>> I have plenty of regular solder, and plenty of flux, now I need
> to
> >>
> >>> buy some solder paste for smd stuff. Any recommendations? I
> would
> >>> like some in a jar and also a syringe just to have both. Is
> >> no-clean
> >>> solder better? Also, I just want tin/lead solder if it is still
> >> available.
> >>>
> >>> Thanks,
> >>>
> >>> Dave
> >>
> >>
>
>
>
>

?

From: [email protected] [mailto:[email protected]] On Behalf Of stefan_trethan
Sent: Wednesday, November 6, 2019 10:16 PM
To: [email protected]
Subject: Re: [homebrewpcbs] Solder paste recommendations

?

?

I've tried thinning old dry paste with denatured alcohol and the result was that the components popped off the board like popcorn as soon as I heated it up.

ST

On Thu, Nov 7, 2019 at 3:35 AM Charlie Hansen <n0tt1@...> wrote:

Thanks Donald....

So, in a way it's like paint...solvent evaporates and the solids settle
out.

I just wonder what chemical the "medium" is....and if more of the same
were added and mixed would that prolong its life even more?? Now, that's
with evaporation....oxidation is quite another issue.? Any thoughts on
that?

Charlie


On Tue, 5 Nov 2019 18:51:04 -0500 "Donald H Locker"
<dhlocker@...> writes:
> The medium carrying the solids changes viscosity as it ages and
> evaporates and oxidises and/or reduces); the solder balls settle as
>
> gravity exerts its ever-present force; the flux reacts with the
> vehicle
> and solder reducing the fluxing potency and the vehicle viscosity
> and
> solder wettability. There are probably other effects, but those are
> the
> big ones that I've read about.
>
> Donald.
> --
> *Plain Text* email -- it's an accessibility issue
> () no proprietary attachments; no html mail
> /\ <>
>
> On 2019-11-05 6:30 p.m., Charlie Hansen wrote:
> > "> Be aware that the rated shelf life is anywhere from 6 months to
> a
> >> year.? It lasts longer if you keep it refrigerated, especially
> after
> >> breaking the seal."
> >
> > Guys, there's something I always wanted to know about that shelf
> > life....what the heck causes the stuff to go bad?
> >
> > Charlie
> >
> >
> > On Tue, 05 Nov 2019 14:51:58 -0700 "Dwayne Reid"
> <dwayner@...>
> > writes:
> >> Hi there.
> >>
> >> We have been purchasing 63/37 solder paste from Chip Quik? -
> both
> >> direct and via Digikey.? It's available in both syringe and jar
> >> form.
> >>
> >> Be aware that the rated shelf life is anywhere from 6 months to
> a
> >> year.? It lasts longer if you keep it refrigerated, especially
> after
> >>
> >> breaking the seal.
> >>
> >> We normally purchase the Water Soluble flux version - we then
> just
> >> wash the boards under running hot water and blow dry with
> compressed
> >>
> >> air.? This works especially well for the small prototype board
> runs
> >> that we do.
> >>
> >> dwayne
> >>
> >>
> >> At 10:39 AM 11/5/2019, Dave wrote:
> >>> I have plenty of regular solder, and plenty of flux, now I need
> to
> >>
> >>> buy some solder paste for smd stuff. Any recommendations? I
> would
> >>> like some in a jar and also a syringe just to have both. Is
> >> no-clean
> >>> solder better? Also, I just want tin/lead solder if it is still
> >> available.
> >>>
> >>> Thanks,
> >>>
> >>> Dave
> >>
> >>
>
>
>
>

The medium carrying the solids changes viscosity as it ages and
evaporates and oxidises and/or reduces); the solder balls settle as

gravity exerts its ever-present force; the flux reacts with the
vehicle
and solder reducing the fluxing potency and the vehicle viscosity
and
solder wettability. There are probably other effects, but those are
the
big ones that I've read about.

Donald.
--
*Plain Text* email -- it's an accessibility issue
() no proprietary attachments; no html mail
/\ <>

On 2019-11-05 6:30 p.m., Charlie Hansen wrote:

"> Be aware that the rated shelf life is anywhere from 6 months to

a

year. It lasts longer if you keep it refrigerated, especially

after

breaking the seal."

Guys, there's something I always wanted to know about that shelf
life....what the heck causes the stuff to go bad?

Charlie


On Tue, 05 Nov 2019 14:51:58 -0700 "Dwayne Reid"

<dwayner@...>

writes:

Hi there.

We have been purchasing 63/37 solder paste from Chip Quik -

both

direct and via Digikey. It's available in both syringe and jar
form.

Be aware that the rated shelf life is anywhere from 6 months to

a

year. It lasts longer if you keep it refrigerated, especially

after

breaking the seal.

We normally purchase the Water Soluble flux version - we then

just

wash the boards under running hot water and blow dry with

compressed

air. This works especially well for the small prototype board

runs

that we do.

dwayne


At 10:39 AM 11/5/2019, Dave wrote:

I have plenty of regular solder, and plenty of flux, now I need

to

buy some solder paste for smd stuff. Any recommendations? I

would

like some in a jar and also a syringe just to have both. Is

no-clean

solder better? Also, I just want tin/lead solder if it is still

available.

Thanks,

Dave

Lead free is, I think, tin, bismuth, and silver (might have remembered this properly).? However, it does not play well with low temperature soldering and is (AFAIK) inferior in all respects to what one would want in solder.? I have never heard of a eutectic mix, so the low melting temperature doesn't happen with lead free.? This puts more stress on parts, let alone makes soldering more difficult.? Yep, tried lead free, didn't' work as well.

Now the chip-quik has a much lower melting point (IIRC, pure bismuth has a rather low mp, but again, could be wrong).? The chip-quik is designed to alloy and melt at a lower temperature, making removal of large ICs easier.

They do say that you can use it for soldering directly, but that's a good question about how and what.

Harvey


On 11/5/2019 4:49 PM, Dave wrote:

Thanks Harvey,
? I bought a syringe of as per Stefan's post above. I have read about a foreign brand named Mechanic that most people give it high marks.

I also watched some video's earlier today about flux cleaners and in one of them they said MG's the winner.

Isn't bizmuth the stuff that is in lead free solder, or is it some new type? I guess it is a new type because from what I read, lead free has a higher melting point that no lead solder. I have no clue as I never tried it.
Dave

Somewhat easier method, but it diverges after you tack down the opposite pins.? If you don't do that, then the solder hardening pulls the chip out of alignment, so do diagonals first then go for the rest.

Once you have all the pins aligned properly with the corners soldered, then add more flux.? You want flux on the top of the pins to the chip.

I use about a 50 mil/ 1/16 diameter metcal tip.

I've found that putting a little solder on the tip (a solder reservoir, but not a hoof tip) and running the tip from the end of the pad up to the pin allows solder to flow from the tip down onto the pad, and covers the "foot" of the chip pin.? If you should happen to hit two pins at the same time, solder may flow to both without shorting the pins.

If you do short the pins, then adding flux and reheating both *can* separate them (not always).? Otherwise the solder wick works wonders.

Note that this works best on boards with a solder mask.

I use 0.015 solder, eutectic, with a flux core.

Harvey


On 11/5/2019 5:59 PM, Jim Higgins wrote:

Lead-free solder is mostly tin, with trace metallic additives to reduce the likelihood that the solder will grow "whiskers."

If interested in details on "tin whiskers," the following is a good overview. You can't retouch a joint to remove whiskers in a satellite.
(metallurgy)



I only mention the following because I can't see much use for soldering paste except for close spaced leads or if you use a reflow oven.

I've done very little soldering of IC packages with many closely spaced leads on four sides. Used to do MIL Spec soldering in the late 60s, but we had nothing like that back then. I used tin-lead solder then and now... darn near hair thin when soldering closely spaced IC packages. Get the super thin stuff and if too thin just double or triple it... thin so there's no chance of getting too much solder and having it short something somewhere out of sight... like under the IC.

My approach - on the rare occasions these days - is to place the multi pin package and tack the thing down with pins aligned with the pads via a few leads on each corner. Then with plenty of flux, solder all leads on one side without worrying whether they're shorted - just don't apply so much solder that it flows where it can't be seen. The less the better, but be sure all pins are soldered to the pads even if shorted. Repeat for all sides. Now apply more flux and lay solder wick along one side and run the soldering tip along it to suck up all excess solder. Same for the other three sides. Inspect closely and apply solder and/or wick if needed... always with plenty of flux.

With this approach the leads all must be at the same level so when the chip is resting on the board before soldering, all leads are in contact with the pads... or at least so close that solder wick won't pull out the solder between lead and pad. Works like a charm. How fast you move the soldering iron tip along the solder wick plays a role in the quality of the job and the need for rework. Start off faster and go slower if pins remain shorted.

Jim H

Lead-free solder is mostly tin, with trace metallic additives to reduce the likelihood that the solder will grow "whiskers."

If interested in details on "tin whiskers," the following is a good overview. You can't retouch a joint to remove whiskers in a satellite.
(metallurgy)



I only mention the following because I can't see much use for soldering paste except for close spaced leads or if you use a reflow oven.

I've done very little soldering of IC packages with many closely spaced leads on four sides. Used to do MIL Spec soldering in the late 60s, but we had nothing like that back then. I used tin-lead solder then and now... darn near hair thin when soldering closely spaced IC packages. Get the super thin stuff and if too thin just double or triple it... thin so there's no chance of getting too much solder and having it short something somewhere out of sight... like under the IC.

My approach - on the rare occasions these days - is to place the multi pin package and tack the thing down with pins aligned with the pads via a few leads on each corner. Then with plenty of flux, solder all leads on one side without worrying whether they're shorted - just don't apply so much solder that it flows where it can't be seen. The less the better, but be sure all pins are soldered to the pads even if shorted. Repeat for all sides. Now apply more flux and lay solder wick along one side and run the soldering tip along it to suck up all excess solder. Same for the other three sides. Inspect closely and apply solder and/or wick if needed... always with plenty of flux.

With this approach the leads all must be at the same level so when the chip is resting on the board before soldering, all leads are in contact with the pads... or at least so close that solder wick won't pull out the solder between lead and pad. Works like a charm. How fast you move the soldering iron tip along the solder wick plays a role in the quality of the job and the need for rework. Start off faster and go slower if pins remain shorted.

Jim H

Hi there.

We have been purchasing 63/37 solder paste from Chip Quik? - both direct and via Digikey.? It's available in both syringe and jar form.

Be aware that the rated shelf life is anywhere from 6 months to a year.? It lasts longer if you keep it refrigerated, especially after breaking the seal.

We normally purchase the Water Soluble flux version - we then just wash the boards under running hot water and blow dry with compressed air.? This works especially well for the small prototype board runs that we do.

dwayne


At 10:39 AM 11/5/2019, Dave wrote:

I have plenty of regular solder, and plenty of flux, now I need to buy some solder paste for smd stuff. Any recommendations? I would like some in a jar and also a syringe just to have both. Is no-clean solder better? Also, I just want tin/lead solder if it is still available.

Thanks,

Dave

Lead-free solder is mostly tin, with trace metallic additives to reduce the likelihood that the solder will grow "whiskers."

If interested in details on "tin whiskers," the following is a good overview. You can't retouch a joint to remove whiskers in a satellite.
(metallurgy)



I only mention the following because I can't see much use for soldering paste except for close spaced leads or if you use a reflow oven.

I've done very little soldering of IC packages with many closely spaced leads on four sides. Used to do MIL Spec soldering in the late 60s, but we had nothing like that back then. I used tin-lead solder then and now... darn near hair thin when soldering closely spaced IC packages. Get the super thin stuff and if too thin just double or triple it... thin so there's no chance of getting too much solder and having it short something somewhere out of sight... like under the IC.

My approach - on the rare occasions these days - is to place the multi pin package and tack the thing down with pins aligned with the pads via a few leads on each corner. Then with plenty of flux, solder all leads on one side without worrying whether they're shorted - just don't apply so much solder that it flows where it can't be seen. The less the better, but be sure all pins are soldered to the pads even if shorted. Repeat for all sides. Now apply more flux and lay solder wick along one side and run the soldering tip along it to suck up all excess solder. Same for the other three sides. Inspect closely and apply solder and/or wick if needed... always with plenty of flux.

With this approach the leads all must be at the same level so when the chip is resting on the board before soldering, all leads are in contact with the pads... or at least so close that solder wick won't pull out the solder between lead and pad. Works like a charm. How fast you move the soldering iron tip along the solder wick plays a role in the quality of the job and the need for rework. Start off faster and go slower if pins remain shorted.

Jim H



Received from Dave at 11/5/2019 21:49 UTC:

Thanks Harvey,
I bought a syringe of <> as per Stefan's post above. I have read about a foreign brand named Mechanic that most people give it high marks.

I also watched some video's earlier today about flux cleaners and in one of them they said MG's the winner.

Isn't bizmuth the stuff that is in lead free solder, or is it some new type? I guess it is a new type because from what I read, lead free has a higher melting point that no lead solder. I have no clue as I never tried it.
Dave