I love the smell of tantalum in the morning
In the case of the rt7 (or knife soldering tips for other brands) you get a
fine point that easily handles 30-32 awg wire, and the edge of the tip is a
little over 100 thou long, so for parts 0805 and smaller you just lay the
edge along the side of the component and heat both pads and swipe it to the
side.
On Sunday, 6 November 2016, Bryan _ bpl521@outlook.com wrote:
If the SMD is small enough I have found it easy to remove by just applying
a blob of solder to one end, this will quickly gap over to the other lead,
and the SMD component and solder ball just slides off the board. Only works
on the very small components though.
-=Bryan=-
From: time-nuts <time-nuts-bounces@febo.com javascript:;> on behalf of
Robert LaJeunesse <lajeunesse@mail.com javascript:;>
Sent: November 6, 2016 8:42 AM
To: time-nuts@febo.com javascript:;
Subject: Re: [time-nuts] I love the smell of tantalum in the morning
Another admittedly low-budget way of heating both ends is to use a heat
spreader. Solder a short piece of braid to one component end, fold it over
the top of the part, and solder it to the other end. Heat the braid in the
center, add solder until both ends are melted, and lift the combination off
with tweezers. Sometimes a heavy enough copper wire bent around the part
will also work as the heat spreader..
Bob LaJeunesse
Sent: Saturday, November 05, 2016 at 9:05 PM
From: "Andy ZL3AG via time-nuts" <time-nuts@febo.com javascript:;>
To: "Discussion of precise time and frequency measurement" <
Subject: Re: [time-nuts] I love the smell of tantalum in the morning
Yes. Unless you're grinding it away with a dremel (which I wouldn't
recommend as far as chemical dust is concerned), nibbling away with
sidecutters would be trying to force the 2 ends of the component apart.
That may be stressing the pads they're soldered to, leading to a possible
pad lifting at some stage.
Any of the methods mentioned that heat both ends at the same time -
allowing the component to be wiped off the board - would have to be the
best, stress-wise.
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By far the easiest method.
-=Bryan=-
From: time-nuts time-nuts-bounces@febo.com on behalf of Scott Stobbe scott.j.stobbe@gmail.com
Sent: November 6, 2016 1:10 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] I love the smell of tantalum in the morning
In the case of the rt7 (or knife soldering tips for other brands) you get a
fine point that easily handles 30-32 awg wire, and the edge of the tip is a
little over 100 thou long, so for parts 0805 and smaller you just lay the
edge along the side of the component and heat both pads and swipe it to the
side.
On Sunday, 6 November 2016, Bryan _ bpl521@outlook.com wrote:
If the SMD is small enough I have found it easy to remove by just applying
a blob of solder to one end, this will quickly gap over to the other lead,
and the SMD component and solder ball just slides off the board. Only works
on the very small components though.
-=Bryan=-
From: time-nuts <time-nuts-bounces@febo.com javascript:;> on behalf of
Robert LaJeunesse <lajeunesse@mail.com javascript:;>
Sent: November 6, 2016 8:42 AM
To: time-nuts@febo.com javascript:;
Subject: Re: [time-nuts] I love the smell of tantalum in the morning
Another admittedly low-budget way of heating both ends is to use a heat
spreader. Solder a short piece of braid to one component end, fold it over
the top of the part, and solder it to the other end. Heat the braid in the
center, add solder until both ends are melted, and lift the combination off
with tweezers. Sometimes a heavy enough copper wire bent around the part
will also work as the heat spreader..
Bob LaJeunesse
Sent: Saturday, November 05, 2016 at 9:05 PM
From: "Andy ZL3AG via time-nuts" <time-nuts@febo.com javascript:;>
To: "Discussion of precise time and frequency measurement" <
Subject: Re: [time-nuts] I love the smell of tantalum in the morning
Yes. Unless you're grinding it away with a dremel (which I wouldn't
recommend as far as chemical dust is concerned), nibbling away with
sidecutters would be trying to force the 2 ends of the component apart.
That may be stressing the pads they're soldered to, leading to a possible
pad lifting at some stage.
Any of the methods mentioned that heat both ends at the same time -
allowing the component to be wiped off the board - would have to be the
best, stress-wise.
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If you are in a position where you are worried about damaging the PCB.
(And I would really be worried cutting any part in half with cutters, or
cutting leads off an IC with diagonal cutters.)
For two leaded parts, "Hot tweezers" work fine.
For parts with more leads, like ICs, you need hot air tools.
If you don't have those tools, or you have an unusually expensive or rare
PCB, consider low temperature solder.
You can buy a kit (from Mouser or others) for $16 called "ChipQuik" SMD1
Watch the video:
http://www.chipquik.com/store/product_info.php?products_id=210001
Manufacturer's Part number SMD1
Mouser part number: 910-SMD1
Remove as much normal (lead containing or lead-free) solder as you can from
each lead with solder wick.
Flood each pin with the low temp solder alloy (melting temp about 136
degrees F or 58 degrees C)
Usually putting a soldering iron on any one pin (or use a hot air pencil)
will raise the entire part and nearby board above 136 degrees F, so just
pick the part off with tweezers.
Now clean off all the low temp solder with solder-wick or as instructed.
For $16, you get enough for several years of casual reworks.
This is much gentler on the PC board than any other technique.
--- Graham
==
On Sun, Nov 6, 2016 at 2:42 PM, Bryan _ bpl521@outlook.com wrote:
If the SMD is small enough I have found it easy to remove by just applying
a blob of solder to one end, this will quickly gap over to the other lead,
and the SMD component and solder ball just slides off the board. Only works
on the very small components though.
-=Bryan=-
From: time-nuts time-nuts-bounces@febo.com on behalf of Robert
LaJeunesse lajeunesse@mail.com
Sent: November 6, 2016 8:42 AM
To: time-nuts@febo.com
Subject: Re: [time-nuts] I love the smell of tantalum in the morning
Another admittedly low-budget way of heating both ends is to use a heat
spreader. Solder a short piece of braid to one component end, fold it over
the top of the part, and solder it to the other end. Heat the braid in the
center, add solder until both ends are melted, and lift the combination off
with tweezers. Sometimes a heavy enough copper wire bent around the part
will also work as the heat spreader..
Bob LaJeunesse
Sent: Saturday, November 05, 2016 at 9:05 PM
From: "Andy ZL3AG via time-nuts" time-nuts@febo.com
To: "Discussion of precise time and frequency measurement" <
Subject: Re: [time-nuts] I love the smell of tantalum in the morning
Yes. Unless you're grinding it away with a dremel (which I wouldn't
recommend as far as chemical dust is concerned), nibbling away with
sidecutters would be trying to force the 2 ends of the component apart.
That may be stressing the pads they're soldered to, leading to a possible
pad lifting at some stage.
Any of the methods mentioned that heat both ends at the same time -
allowing the component to be wiped off the board - would have to be the
best, stress-wise.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/
mailman/listinfo/time-nuts
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com/cgi-bin/mailman/listinfo/time-nuts>
www.febo.com
time-nuts is a low volume, high SNR list for the discussion of precise
time and frequency measurement and related topics. To see the collection of
prior postings to ...
and follow the instructions there.
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and follow the instructions there.
On 11/6/16 10:47 AM, Adrian Godwin wrote:
You might also want normal cold tweezers to place the part. I'm not sure
what an orange stick is, around here I'd use a wooden toothpick. Perhaps
that's the same thing !
An orange stick is a piece of wood about 1/4" in diameter which has been
tapered and then trimmed to a chisel point. I don't know if they were
originally colored orange, or they're made from the wood of orange trees
or what.
A quick google says they're also used for nail art and cuticle pushing,
and are made from orangewood. I note that orangewood doesn't
necessarily mean "wood from orange trees", which I can't imagine being a
good lumber to process (small diameter, not straight, etc.).
I would guess that they're made from fir or birch or something which
comes in logs and has straight grain - essentially a giant toothpick.
Any way, they are non-magnetic, non conductive (but not an insulator, so
they're ESD safe), a thermal insulator (so the heat on your part isn't
sucked into the tool).
They're also great for pushing a SMD part off the pads gently when the
solder has been liquified.
And for holding copper foil snowflakes when tuning a microwave circuit
The Swiss Venus tweezers have a lovely finish and the ends always meet.
There are probably others as good.
If you get some placing tweezers, make sure they're antimagnetic. Some
small parts (even resistors, that I wouldn't expect to contain steel) seem
to stick even to stainless steel. I've also heard bambooo tweezers are
good, but have never tried them.
On Sun, Nov 6, 2016 at 6:17 PM, jimlux jimlux@earthlink.net wrote:
On 11/6/16 9:24 AM, Scott Stobbe wrote:
I would not recommend purchasing soldering tweezers without trying them
first. They are not easy to control solder application when mounting a
component.
tweezers to remove
single iron to install
use a orange stick to hold the part down while you solder each end.
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Am 06.11.2016 um 22:16 schrieb Bryan _:
That must be the guy who removes the e**y MV-89s from China from their
boards.
At least two of mine have scars that are best explained by such a tool.
regards, Gerhard
Thank you everyone for the superb set of replies to this posting over the weekend. I'm sure I will have my 5071A boards working again shortly. Thanks also for the generous offers on- and off-list from people who do this professionally. The level of hands-on experience on this list is amazing.
If there's more to add to the thread in the coming week, perhaps send it to me off-list.
Thanks,
/tvb
----- Original Message -----
From: "Tom Van Baak" tvb@LeapSecond.com
To: "Discussion of precise time and frequency measurement" time-nuts@febo.com
Sent: Saturday, November 05, 2016 11:12 AM
Subject: [time-nuts] I love the smell of tantalum in the morning
See C13 in the attached photo. I need to replace some blown caps on a few boards [1]. In one instance the cap got so hot it melted itself off the board. Quiet convenient, actually -- it acts like its own fuse -- but I don't think the 5071 designers had that clever feature in mind.
Having not done SMT before, how should I do it with minimal risk to the very precious PCB. Or, what equipment should I use this as a good excuse to buy?
Thanks,
/tvb
[0] http://www.imdb.com/title/tt0078788/quotes
[1] http://leapsecond.com/museum/hp5071a/A1-mother.htm
So what are the odds that the failed cap would be C13?
Is this cause for triskaidekaphobia? ;-)
Please pardon this random excursion outside the bounds of precision
time.
Bill Hawkins
(who learned not to let kakorraphiophobia lead me to osphresiolagnia
[bad odors, not erotic] in college)