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'[EE] Trays for MSL Baking'
2007\06\05@220222
by
Forrest Christian
So, I've got a couple components on my new board that have a MSL of 3,
which basically means that I'm going to have to bake the components at
125*C overnight before I can use them in assembly (since I will have a
lot of open stock).
I have acquired a suitable used industrial oven to do this in. What I
can't find is some sort of designed-for-this-purpose tray to put the
components on to put in the oven. Before I just go out and grab a
cookie sheet for this purpose, are there special ESD trays for this?
-forrest
2007\06\06@082435
by
Carl Denk
Not terribly conversant on this topic, but aren't ESD trays conductive,
and cookie sheets are steel (could be stainless) which is conductive
(except the coated non-stick variety), therefore would meet the ESD
requirement. Possibly need a ground wire while loading/unloading (wire
with 2 alligator clips). :)
Forrest Christian wrote:
{Quote hidden}> So, I've got a couple components on my new board that have a MSL of 3,
> which basically means that I'm going to have to bake the components at
> 125*C overnight before I can use them in assembly (since I will have a
> lot of open stock).
>
> I have acquired a suitable used industrial oven to do this in. What I
> can't find is some sort of designed-for-this-purpose tray to put the
> components on to put in the oven. Before I just go out and grab a
> cookie sheet for this purpose, are there special ESD trays for this?
>
> -forrest
>
2007\06\06@154535
by
Carey Fisher
Forrest,
What's MSL and why does it matter?
Thanks,
Carey
Forrest Christian wrote:
> So, I've got a couple components on my new board that have a MSL of 3,
> which basically means that I'm going to have to bake the components at
> 125*C overnight before I can use them in assembly (since I will have a
> lot of open stock).
>
2007\06\06@163155
by
Peter van Hoof
See these sites
en.wikipedia.org/wiki/Moisture_Sensitivity_Level
http://www.jedec.org/download/search/jstd020c.pdf
Basically MSL is moisture sensitivity level 3=168 hours max time
after opening package before it needs to be re-flowed/soldered
If it is not soldered within this time-span it will need a bake before doing so
If this is not done moisture trapped in the device can turn to steam and
damage the device (immediately or over time)
Peter van Hoof
{Original Message removed}
2007\06\06@164112
by
Peiserma
2007\06\07@034554
by
Forrest W Christian
Carey Fisher wrote:
>Forrest,
>What's MSL and why does it matter?
>
Others have answered with what it is... basically a rating which has to
do with absorbtion of moisture from the air which vaporizes during
soldering cracking the package (or doing other damage).
What is scary is how many packages are at MSL 3 or above. What is
biting me are the regulators I want to use which are in a TO-263 package
which is basically a surface mount version of the TO-220. Once I open
the package I have to use all of them within 7 days or I have to bake
them at 125*C for at least 8 hours to dry them out before I do use them.
-forrest
2007\06\07@113437
by
Bob Barr
|
On Thu, 07 Jun 2007 01:47:22 -0600, Forrest W Christian wrote:
>Carey Fisher wrote:
>
>>Forrest,
>>What's MSL and why does it matter?
>>
>Others have answered with what it is... basically a rating which has to
>do with absorbtion of moisture from the air which vaporizes during
>soldering cracking the package (or doing other damage).
>
>What is scary is how many packages are at MSL 3 or above. What is
>biting me are the regulators I want to use which are in a TO-263 package
>which is basically a surface mount version of the TO-220. Once I open
>the package I have to use all of them within 7 days or I have to bake
>them at 125*C for at least 8 hours to dry them out before I do use them.
>
Something doesn't sound right about that. Aren't there provisions in
MSL handling procedures that allow for resealling the devices that
won't be used over the next 7 days?
You may be able to avoid some bake-outs by doing this. I'll see if I
can find a link on the topic.
Regards, Bob
2007\06\07@115243
by
Alan B. Pearce
>Something doesn't sound right about that. Aren't there provisions
>in MSL handling procedures that allow for resealling the devices
>that won't be used over the next 7 days?
Umm, yeah, if you put dry dessicant in the bag and heat seal it ...
Not too many hobbyists would have a heat sealer handy, would they?
2007\06\07@123044
by
Bob Blick
--- "Alan B. Pearce" <spam_OUTA.B.PearceTakeThisOuT
rl.ac.uk> wrote:
> Umm, yeah, if you put dry dessicant in the bag and
> heat seal it ...
>
> Not too many hobbyists would have a heat sealer
> handy, would they?
I've got a hot glue gun right here, that should be
fine for that purpose.
Cheerful regards,
Bob
2007\06\07@161427
by
Robert Rolf
Alan B. Pearce wrote:
>>Something doesn't sound right about that. Aren't there provisions
>>in MSL handling procedures that allow for resealling the devices
>>that won't be used over the next 7 days?
>
>
> Umm, yeah, if you put dry dessicant in the bag and heat seal it ...
>
> Not too many hobbyists would have a heat sealer handy, would they?
It's called a 'metal ruler and soldering iron'.
You draw the iron tip quickly across the plastic baggy
(at a low angle) while holding the end closed with the metal ruler. You get a good seal
after a bit of practice to get the speed right.
Too fast you don't seal. Too slow and you melt through.
I do it all the time and it gives a nice hermetic seal.
You can also fold the open end over several times and tape fully (using packing
tape or 'vapor barrier' tape used in home construction.
Robert
2007\06\07@222601
by
Peter Todd
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Hash: SHA1
On Thu, Jun 07, 2007 at 04:52:39PM +0100, Alan B. Pearce wrote:
> >Something doesn't sound right about that. Aren't there provisions
> >in MSL handling procedures that allow for resealling the devices
> >that won't be used over the next 7 days?
>
> Umm, yeah, if you put dry dessicant in the bag and heat seal it ...
>
> Not too many hobbyists would have a heat sealer handy, would they?
Surely a zip-lock bag would be good enough if you put dessicant in it?
- --
http://petertodd.ca
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2007\06\07@231241
by
William Chops Westfield
>> Not too many hobbyists would have a heat sealer
>> handy, would they?
>>
Not too many hobbyists wave/reflow solder, and I don't
think it's expected to be a big issue for hand soldering.
I suspect MSL3 "bake for 8 hours" is becoming like "wash
under running water for 15 minutes"; a standard instruction
applied to almost everything whether it makes sense or not.
:-(
BillW
2007\06\07@232429
by
Carey Fisher
Forrest W Christian wrote:
> Carey Fisher wrote:
>
>
>> Forrest,
>> What's MSL and why does it matter?
>>
>>
> Others have answered with what it is... basically a rating which has to
> do with absorbtion of moisture from the air which vaporizes during
> soldering cracking the package (or doing other damage).
>
> What is scary is how many packages are at MSL 3 or above. What is
> biting me are the regulators I want to use which are in a TO-263 package
> which is basically a surface mount version of the TO-220. Once I open
> the package I have to use all of them within 7 days or I have to bake
> them at 125*C for at least 8 hours to dry them out before I do use them.
>
> -forrest
>
Doesn't it matter what the relative humidity is where the parts are kept
after opening the package?
Carey
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