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Discussion Groups | Comp.Arch.Embedded | bake the IC before mounting?

There are 6 messages in this thread.

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bake the IC before mounting? - 2005-01-28 22:52:00

I bought some AM186 and AM188 IC's. The caution note on the bag says if I
use infered or vaper-phase reflow, after I open the bag, I need to install
the IC's in 168 hours, if I don't store them in places with relative
humidity of <20% after opening. Otherwise I need to bake them (192 hours at
40C and 5% or 24 hours at 125C). I think this requirement is hard to
understand. If they are not wet, I can't see how a little bit humidity
would distroy them when I reflow them in the oven. Can somebody enlighten
me? Thank you.

vax, 9000


Re: bake the IC before mounting? - Spehro Pefhany - 2005-01-28 23:21:00

On Fri, 28 Jan 2005 22:52:21 -0500, the renowned "vax, 9000"
<v...@gmail.com> wrote:

>I bought some AM186 and AM188 IC's. The caution note on the bag says if I
>use infered or vaper-phase reflow, after I open the bag, I need to install
>the IC's in 168 hours, if I don't store them in places with relative
>humidity of <20% after opening. Otherwise I need to bake them (192 hours at
>40C and 5% or 24 hours at 125C). I think this requirement is hard to
>understand. If they are not wet, I can't see how a little bit humidity
>would distroy them when I reflow them in the oven. Can somebody enlighten
>me? Thank you.
>
>vax, 9000

There is a bit of moisture in popcorn kernels. Same thing. 



Best regards, 
Spehro Pefhany
-- 
"it's the network..."                          "The Journey is the reward"
s...@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Re: bake the IC before mounting? - Rich Webb - 2005-01-28 23:47:00

On Fri, 28 Jan 2005 22:52:21 -0500, "vax, 9000" <v...@gmail.com>
wrote:

>I bought some AM186 and AM188 IC's. The caution note on the bag says if I
>use infered or vaper-phase reflow, after I open the bag, I need to install
>the IC's in 168 hours, if I don't store them in places with relative
>humidity of <20% after opening. Otherwise I need to bake them (192 hours at
>40C and 5% or 24 hours at 125C). I think this requirement is hard to
>understand. If they are not wet, I can't see how a little bit humidity
>would distroy them when I reflow them in the oven. Can somebody enlighten
>me? Thank you.

Google for the terms "popcorn reflow humidity" or similar for some
lengthy explanations and a few nice pictures.

-- 
Rich Webb   Norfolk, VA

Re: bake the IC before mounting? - Tim Wescott - 2005-01-29 01:22:00

Spehro Pefhany wrote:

> On Fri, 28 Jan 2005 22:52:21 -0500, the renowned "vax, 9000"
> <v...@gmail.com> wrote:
> 
> 
>>I bought some AM186 and AM188 IC's. The caution note on the bag says if I
>>use infered or vaper-phase reflow, after I open the bag, I need to install
>>the IC's in 168 hours, if I don't store them in places with relative
>>humidity of <20% after opening. Otherwise I need to bake them (192 hours at
>>40C and 5% or 24 hours at 125C). I think this requirement is hard to
>>understand. If they are not wet, I can't see how a little bit humidity
>>would distroy them when I reflow them in the oven. Can somebody enlighten
>>me? Thank you.
>>
>>vax, 9000
> 
> 
> There is a bit of moisture in popcorn kernels. Same thing. 
> 
Except the AM186 won't taste as good, and you will probably have 
significantly more old maids.

-- 

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

Re: bake the IC before mounting? - David Powell - 2005-01-29 12:00:00

Hi,

Every device has a moisture sensitivity level ( MSL ).... This outlines how
long the device can be out of it's foil package, before it needs to be
re-baked, to dry out the device.

A MSL of 1 means the device can be used without any baking, no matter how
long it was out of the foil packet, not many devices have an MSL of 1.

The MSL rating is given to a particular device ( or probably more correctly
to a particular package ) after testing, ie the device is soaked in a
particular relative humidity, then it is sent through a re-flow process,
then the packaged is analysed for any changes in the structure.

Optical packages are particularly sensitive to moisture, this is cause they
don't have any quarts in the plastic. LEDs are know to some times "pop" due
to the moisture expanding in the material.

In saying all that, you would only typically see a very small fall out due
to MSL problems.


"vax, 9000" <v...@gmail.com> wrote in message
news:ctf11i$t7q$1...@charm.magnus.acs.ohio-state.edu...
> I bought some AM186 and AM188 IC's. The caution note on the bag says if I
> use infered or vaper-phase reflow, after I open the bag, I need to install
> the IC's in 168 hours, if I don't store them in places with relative
> humidity of <20% after opening. Otherwise I need to bake them (192 hours
at
> 40C and 5% or 24 hours at 125C). I think this requirement is hard to
> understand. If they are not wet, I can't see how a little bit humidity
> would distroy them when I reflow them in the oven. Can somebody enlighten
> me? Thank you.
>
> vax, 9000
>



Re: bake the IC before mounting? - An Schwob in USA - 2005-01-29 16:59:00

Friendly amendment

Usually the popcorn effect does not show up as a failure right away but
as corrosion months or years later.
ALso these small cracks can often not be seen without a microscope.

For any kind of product that you will be liable for, just make sure you
use the open package in 168h

Schwob

David Powell wrote:
> Hi,
>
> Every device has a moisture sensitivity level ( MSL ).... This
outlines how
> long the device can be out of it's foil package, before it needs to
be
> re-baked, to dry out the device.
>
> A MSL of 1 means the device can be used without any baking, no matter
how
> long it was out of the foil packet, not many devices have an MSL of
1.
>
> The MSL rating is given to a particular device ( or probably more
correctly
> to a particular package ) after testing, ie the device is soaked in a
> particular relative humidity, then it is sent through a re-flow
process,
> then the packaged is analysed for any changes in the structure.
>
> Optical packages are particularly sensitive to moisture, this is
cause they
> don't have any quarts in the plastic. LEDs are know to some times
"pop" due
> to the moisture expanding in the material.
>
> In saying all that, you would only typically see a very small fall
out due
> to MSL problems.
>
>
If they are not wet, I can't see how a little bit humidity
> > would distroy them when I reflow them in the oven. Can somebody
enlighten
> > me? Thank you.
> >
> > vax, 9000
> >