by the way, I trained hunt shooting in a simulator for the first time. The
program consisted of using shotgun and rifle, you could select caliber,
velocity and a lot of shell parameters and then go hunting birds, deers,
rabbits, bears, moose, anything.
You could then study each moment statistically, how you aimed, exact where
you hit the animal etc.The screen was about 10 meters wide and three meters
high. A camera and a laser fitted on the weapon made the orientation on the
screen and some sort of sensors communicated with a computer. You don't need
pay for ammunition, are under roof, only 60 dB noise and you can manipulate
the animals moving, fast or rapid, coming spontaneous or planned ...really
interesting. Most frightening was when I hurt a bear and he changed
direction towards me. The leader told me too shoot no closer than 40 meters.
If you let a bear come closer, you are dead, because even if you hit some
parts of his body, he will run on you by mear reflexes. A hunte was killed
not far from here this year exactly like this. He was found stone dead..with
200 kg dead bear over his body. He fired at 20 meters..
Inge
----- Original Message -----
From: "Dwight Mattix" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Thursday, September 10, 2009 9:19 PM
Subject: Re: [TN] Need clever comments
> At 11:52 AM 9/10/2009, Dwight Mattix wrote:
>>At 10:45 AM 9/10/2009, Stadem, Richard D. wrote:
>> >Or hanging around the Laundromat with his .44 automatic.
>>
>>.44 automatic? I didn't take Steve for a Desert Eagle sort of guy.
>
> On second thought, weren't you a P-3 sailor?
>
> In which case I'd empathize with any Mall Cop type frustrations and
> resultant compensating behaviors. Maybe we could all pass the hat and
> help raise funds for a tactical wheelbarrow to go with the Desert Eagle
> and Tactical Segway.
>
>
>
>> >-----Original Message-----
>> >From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge
>> >Sent: Thursday, September 10, 2009 11:25 AM
>> >To: [log in to unmask]
>> >Subject: Re: [TN] Need clever comments
>> >
>> >I will post a handful SEM images to Steve, so you get an idea what it's
>> >all
>> >about.
>> >It may take a while, because he is probably on the market place to buy
>> >curtains and wallpaper
>> >for his new appartment. Or jogging. Or having a drink on the balcony.
>> >/Inge
>> >
>> >
>> >----- Original Message -----
>> >From: "Inge" <[log in to unmask]>
>> >To: <[log in to unmask]>
>> >Sent: Thursday, September 10, 2009 5:10 PM
>> >Subject: Re: [TN] Need clever comments
>> >
>> >
>> > > Jack &Paul, FYI.
>> > >
>> > > Today I had a close look at the cross sections. What I found was
>> > > this:
>> > >
>> > > 1. The Tin plating was done AFTER solder mask (Jack was right)
>> > > 2. The solder mask was very uneven, thickness between 5um and 25 um.
>> > > 3. Despite the corrupted surface, the solder mask is homogenous, no
>> > > vertical cracks found.
>> > > 4. The copper that I found earlier on top of the conductor, i.e. on
>> >the
>> > > solder mask, that copper had no connection with the conductor copper.
>> > > Which means that these contaminations had NOT migrated through the
>> >solder
>> > > mask.
>> > > 5. I can still not figure out from where the copper contaminations
>> >come.
>> > >
>> > > So, all that remains is the question about the copper contaminations
>> >tha
>> > > embedded in the very surface of the solder mask. I have to adjust my
>> > > report and resend it to our customer and the board maker.
>> > >
>> > > Thanks to your critisism, I can now redo the analys, starting from a
>> >more
>> > > correct standpoint.
>> > >
>> > > Your are great!
>> > >
>> > > /Inge
>> > >
>> > >
>> > >
>> > >
>> > > ----- Original Message -----
>> > > From: "Inge" <[log in to unmask]>
>> > > To: <[log in to unmask]>
>> > > Sent: Wednesday, September 09, 2009 8:09 PM
>> > > Subject: Re: [TN] Need clever comments
>> > >
>> > >
>> > >> Jack,
>> > >>
>> > >> SMOBC is the common industrial standard, as you pointed out,
>> > >> however,
>> >
>> > >> there ARE some fabricators that apply the solder mask after
>> >Tin/Lead-ing
>> > >> the copper traces. The later method has an obvioius disadvantage,
>> > >> see
>> >
>> > >> below quoted from an article written by US Environmental Agency:
>> > >>
>> > >> " This method predominates for several reasons. Copper is a surface
>> >that
>> > >> lends itself to rigorous cleaning, which is essential for solder
>> > >> mask
>> >
>> > >> adhesion. Tin-lead under solder mask will liquefy during soldering
>> >and
>> > >> may cause the mask to blister and peel. The hot air solder leveling
>> > >> process generally produces less waste water and introduces less lead
>> >into
>> > >> the waste water stream than tin-lead plating and reflow. Despite
>> >these
>> > >> advantages, well-known disadvantages also exist. The shelf-life of
>> >hot
>> > >> air solder leveled circuits is short and solder thicknesses on pads
>> >and
>> > >> hole barrels is notoriously difficult to control. For these reasons,
>> >a
>> > >> small minority of specifications continue to call for tin-lead plate
>> >and
>> > >> reflow or other alternati air solder leveling, nomenclature
>> >screening,
>> > >> and finally, gold edge plating if necessary. "
>> > >>
>> > >> I think that is what happened to our boards....." cause the mask to
>> > >> blister and peel"...
>> > >>
>> > >> Another paper describes Tin under solder mask this way:
>> > >>
>> > >> " Facility F initially was concerned with the soldermask breakdown
>> >where
>> > >> the Tin leaches underneath the soldermask....etc"
>> > >>
>> > >> Quoted from EPA (United States Environmental Protection Agency.
>> > >>
>> > >> When I started the investigation (had just some hours to spend
>> > >> before
>> >
>> > >> reporting the result!), I was fully convinced that these boards were
>> > >> SMOBC, but our customer said they used tinning before soldermask. I
>> >have
>> > >> asked for a confirmation from the board fabricator, but got no
>> >answer.
>> > >>
>> > >> Thanks for your comment, good critics.
>> > >>
>> > >> Inge
>> > >>
>> > >>
>> > >> ----- Original Message -----
>> > >> From: "Jack Olson" <[log in to unmask]>
>> > >> To: <[log in to unmask]>
>> > >> Sent: Wednesday, September 09, 2009 4:44 PM
>> > >> Subject: [TN] Need clever comments
>> > >>
>> > >>
>> > >>>I know I'm late to the game, but I can't resist asking this
>> > >>>question:
>> > >>>
>> > >>>>From my experience, the tin is applied AFTER soldermask, so
>> > >>> you have mask over bare copper, and tin over exposed copper.
>> > >>>
>> > >>> The tin in PHOTO2.JPG in the exposed area looks beautiful,
>> > >>> so isn't the question (ignoring the whiskers for the moment)
>> > >>> "How can bare copper erupt through the mask?"
>> > >>>
>> > >>> Unless I missed one of your previous posts, it seems to me that
>> > >>> any speculation about copper poking through the tin finish is
>> > >>> irrelevant. I'm only addressing Question 2 below, but you mentioned
>> > >>> introducing a nickel barrier, and that will not be plated under the
>> >mask
>> > >>> either, will it? only on exposed circuitry...
>> > >>>
>> > >>> just wondering,
>> > >>> Jack
>> > >>>
>> > >>>
>> > >>> -=-=-=-
>> > >>>
>> > >>> *Subject:* Need clever comments *From:* Hernefjord Ingemar <
>> > >>> [log in to unmask]> *Reply-To:* TechNet E-Mail Forum
>> > >>> <
>> > >>> [log in to unmask]>, Hernefjord Ingemar
>> ><[log in to unmask]>
>> > >>> *
>> > >>> Date:* Mon, 7 Sep 2009 13:21:54 +0200 *Content-Type:* text/plain
>> > >>>
>> > >>>
>> > >>> Hi all, need some professional backup regarding MIL quality boards.
>> > >>>
>> > >>> Objects: FR-4 Class III double-sided multi-layer boards, populated
>> > >>> with SOICS, BGAs,and a lot of passive components.
>> > >>>
>> > >>> Observation 1 : the non soldered board have lots of Tin whiskers on
>> > >>> inside of the PTH barrel. My thought is this: if whiskers can grow
>> > >>> long before the board is assembled, then ain't it likely that even
>> >CAF
>> > >>> can be generated? See photo 1.
>> > >>>
>> > >>> Observation 2: Copper has somehow penetrated the solder mask. This
>> > >>> can be found everywhere along the conductor traces. You need a very
>> > >>> good light microscope and a SEM to see it. See photo 2.
>> > >>>
>> > >>> Board data: Copper with 0.8 micrometer Immersion Tin. No nickel
>> > >>> barrier. Solder mask thickness not specified.
>> > >>>
>> > >>> Application: Typical MIL-883 environment
>> > >>>
>> > >>> Q1: What is your opinion about that thin Tin directly on copper? I
>> > >>> dislike the concept. Copper is very mobile at high temperatures,
>> > >>> and
>> > >>> combined with humidity, there can be leakage currents and corrosion
>> > >>> issues. Even if the boards are CCd, there is a risk with copper .
>> > >>>
>> > >>> Q2: I gave the advice to introduce a nickel barrier, but our
>> >customer
>> > >>> claimed, that they can't because of pressfit connectors and
>> > >>> pressfit
>> > >>> test pins on the board. Furthermore, they had heard that one cannot
>> > >>> have nickel platings when pressfitting, because the nickel will
>> >crack
>> > >>> and oxidize and cause electrical disfunction. Is this your opinion
>> > >>> too? Are there any relevant testing behind such statements?
>> > >>>
>> > >>> Thanks in advance
>> > >>>
>> > >>> Inge
>> > >>>
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