Conventional 6,6 Nylon which has alternating A & B components, each with a
6 carbon backbone, is often drawn after hot melt spinning to 'set' the
properties. After the drawing, that's it. One of the military aspects of this
drawing in WW2 was the use of undrawn nylon ropes to pull the loaded
gliders off the ground for the trip to Europe. As you can imagine, there was
quite a shock when the tow bomber took off and the shock of the glider take-off
traveled down the tow rope to the gliders still sitting on the ground. The
pull on the undrawn tow rope, which gave it a typical 4x draw, enable the
rope to take up the shock of glider take off. The ropes could just be used
once for this purpose, but could be used for other purposes afterwards.
Enjoy the trivia!! One of the components of 6,6 nylon is adipic acid, which
has been used as an activator in many low residue flux formulations...
Bill Kenyon
Global Centre Consulting
3336 Birmingham Drive
Fort Collins, CO 80526
Tel: 970.207.9586 Cell: 970.980.6373
=======================================================================
In a message dated 5/13/2009 3:13:40 P.M. Mountain Daylight Time,
[log in to unmask] writes:
> OK Genny,
> seems to me as a ordinary 12V 4pole supply connector or like. Why
bother.
> They are soldered by a million every day, and seemingly they work.
Forget
> the 5aMSL, the manufacturer's way to point on the possibility that they
> COULD absorb water vapor, but everything can do that. If you do the
right
> thing you will manage those conns as well as all other hundreds of
> assembly lines around. As someone said, if too much humidity comes in,
> they'll pop, but you don''t know until tested.
>
>
> Nylon ropes are a product of World War II, developed when the United
> States assembled an army alpine division. Starting from scratch, the
U.S.
> developed a number of new products for those troops: nylon rope was one
of
> them.
>
> Nylon ropes have a much greater strength than hemp ropes, are easier to
> handle, maintain strength when wet, don't rot, and can be manufactured
to
> have specific desirable characteristics. While nylon ropes can be cut if
> run over a sharp edge and will deteriorate in sunlight, all in all
they're
> a major improvement over hemp ropes.
>
>
> - Demetri Kolokotronis
>
> So, the women have american alpinists to thank for the nylons?
>
> Inge
>
> ----- Original Message -----
> From: "Genny Gibbard" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Wednesday, May 13, 2009 10:23 PM
> Subject: Re: [TN] Nylon connectors - moisture sensitivity
>
>
> This is a shrouded header, 2mm spacing on the pins. Basic. Nothing
high
> frequency.
> It is surface mount, it is designed for reflow. This one is specified
> that it can withstand one reflow of 260C for 10 seconds.
> When this connector arrived, it was in MBB packaging.
> When we asked about that, we were told, 'treat it as equivalent to 5a
> MSL'. This is the first time I have ever heard of a basic connector
being
> MSL.
> We received it on tape and reel.
> However, we were told that if it is out of MBB for longer than 24 hours
> that we should bake at 120C for 4 hours.
> We will have to take it out of T&R to do that, which means it would need
> to be repackaged.
>
> I should clarify - when I talked about melting connectors I was talking
in
> general terms, not this specific connector. I'm sure we've all melted a
> connector from time to time.
> I was trying to understand what would happen, what kind of damage would
we
> see, if it was moisture-laden and we reflowed it anyway?
>
> Genny
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Inge
> Sent: May 13, 2009 1:22 PM
> To: [log in to unmask]
> Subject: Re: [TN] Nylon connectors - moisture sensitivity
>
> Genny,
> first of all, you should ask yourself :
> - what is the system impedance (50 Ohm or MOhms)
> - signal levels
> - current levels
> - DC?
> - AC?
> - data lines?
> - wave form?
> - S/N requirements?¨
> - Insulation requirements (flashover risk)
> - pin/sleeve basic metal?
> - ditto plating?
> - migration condtions?
> - nylon reinforcement?
>
> Then you can judge the situation and decide what level of risk.
> In certain situations not even Teflon is satisfactory.
>
> Inge
>
> ----- Original Message -----
> From: "Genny Gibbard" <[log in to unmask]>
> To: <[log in to unmask]>
> Sent: Wednesday, May 13, 2009 8:43 PM
> Subject: [TN] Nylon connectors - moisture sensitivity
>
>
> We have been told that a surface mount nylon connector we use is
> moisture sensitive, and should be treated as equivalent to level 5a.
> This is the highest level we have ever seen on any component we have
> used of any type. I didn't think that a connector could be moisture
> sensitive. Not heat tolerant, yes - we have melted a few - but moisture
> sensitive?
> What kind of damage can happen to a nylon connector from too much
> moisture absorption?
> Thanks in advance for your responses.
>
> Genny
>
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