[SI-LIST] Re: soldering plastic balls
- From: "Moreira, Jose" <jose.moreira@xxxxxxxxxx>
- To: <olaney@xxxxxxxx>, <weirsi@xxxxxxxxxx>
- Date: Tue, 5 Jun 2007 14:28:19 -0500
Orin, Steve
On the topic of outer layer conductor for HF equalization, do you know =
of any cable assembly manufacturers having already on their portfolio =
this type of conductors available for ordering?=20
I have read about them but I have not seen this type of conductors being =
used even on application requiring long coaxial cables for high-speed =
digital applications. I'm wondering why?
Jose
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] =
On Behalf Of olaney@xxxxxxxx
Sent: Dienstag, 5. Juni 2007 21:10
To: weirsi@xxxxxxxxxx
Cc: write2larsj@xxxxxxxxx; dan1_st@xxxxxxxxx; si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: soldering plastic balls
That's the same theory that works for copperweld coax conductors (copper
plated steel). At HF the signal sees only the copper plating, at LF the
resistance does not drop as much from the HF value, ...and it's cheaper!
Orin
On Tue, 05 Jun 2007 11:57:51 -0700 steve weir <weirsi@xxxxxxxxxx> =
writes:
> Lars, the technique of using only an outer layer conductor for HF=20
> equalization is well established. There is a nifty interposer=20
> connector=20
> technology that uses tiny silver plated nickel balls.
>=20
> Regards,
>=20
>=20
> Steve.
> Lars Juul wrote:
> > Hi Steve,
> >
> > I'm surprised to hear that the primary objective with the plastic=20
> core=20
> > balls is to equalize the resistance over frequency, as Sekisui=20
> write=20
> > on their product page:
> >
> > ( http://www.sekisui-fc.com/eng/html/jissou/product/jipr_02.html)
> > ...
> > Micropearl SOL is a solder plated true sphere with a plastic core=20
> and=20
> > was designed for mounting chips to circuit board. Unlike=20
> conventional=20
> > solder balls which often cracks under the heat cycle test,
> > ...
> >
> > They go on to show graphs with how much longer these solderjoints=20
> will=20
> > hold in temp cycle tests comparison to SnAg alloys, which I feel=20
> is=20
> > very relevant in these RoHS times.
> >
> > However, it's true that at high frequencies the current flows on=20
> the=20
> > edge of the conductor (in closest possible proximity to your=20
> return=20
> > current), and that the lack of conductor diameter will lead to=20
> > increased resistance closer to low frequencies, but I doubt that=20
> it=20
> > will act as a good loss equalizer (I might be wrong, I guess)
> >
> >
> > 2007/6/5, steve weir <weirsi@xxxxxxxxxx=20
> <mailto:weirsi@xxxxxxxxxx>>:
> >
> > Lars, the idea of the plastic balls is that they have only a=20
> thin
> > outer
> > conducting layer and therefore the resistance remains much=20
> more
> > uniform
> > and therefore equalizing loss across a broad frequency range.
> >
> > Steve.
> > Lars Juul wrote:
> > > Hi David,
> > > I would call up your packaging vendor and ask them to make a
> > test build with
> > > ball samples from Sekisui on existing 10 Gbps BGAs, provided=20
> the
> > ball attach
> > > tool is suitable for this. This is usually the stumbling=20
> block,
> > as this is
> > > very expensive in NRE.
> > >
> > > Alternatively, it's worth exploring if you make a manual=20
> ball attach
> > > (possible if the packages are for small form factor 10Gbps=20
> CDRs, for
> > > instance) by printing solder paste on the package lands=20
> first,
> > and then
> > > manually place the balls on the paste by a trained person=20
> with
> > a steady
> > > hand. I assure you, crazier things have been made.
> > >
> > > On the other hand, my only concern with this kind of balls=20
> would
> > be the
> > > suitability for them in the power supply, as I imagine the
> > current carrying
> > > capabilities are somewhat limited if you have a plastc core=20
> on
> > the inside.
> > > (I don't think it's possible to attach solid solder and=20
> plastic
> > balls on
> > > specific lands on the package in a high volume setup, yet)
> > >
> > > PS: you're asking whether they work at 10GHz, which is a=20
> single
> > frequency
> > > point, I think it's feasible to use plastic core balls for a
> > narrowband
> > > application, but if it's broadband from 0 to 10e9 Hz you're
> > driving at, I'd
> > > say, try it out in practise first to see if it flies, then=20
> make
> > a full wave
> > > or macromodel of package afterwards to feed the chip I/O=20
> designers.
> > >
> > > Have fun.
> > >
> > > Best regards,
> > > Lars
> > >
> > > 2007/6/5, david stern <dan1_st@xxxxxxxxx
> > <mailto:dan1_st@xxxxxxxxx>>:
> > >
> > >> hello all
> > >>
> > >> I was looking for bga soldering balls technology for an
> > >> application working at 5GHz to 10GHZ and and found
> > >> soldering plastic balls from SEKISUI. Did somebody work=20
> with
> > them at
> > >> 10Ghz?
> > >>
> > >> Thanks
> > >>
> > >> David
> > >>
> > >>
> > >> ---------------------------------
> > >> Moody friends. Drama queens. Your life? Nope! - their life,
> > your story.
> > >> Play Sims Stories at Yahoo! Games.
> > >>
> > >>=20
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