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February 2005

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Subject:
From:
Leo Higgins <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Leo Higgins <[log in to unmask]>
Date:
Wed, 2 Feb 2005 01:19:58 -0800
Content-Type:
text/plain
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text/plain (259 lines)
I am in California this week so while it is late it is actually 2 hours
earlier than the time stamp on my email.

Would standard epoxy mold compound work?  These materials are very fluid at
the mold temp (typ about 175C).  The materials typically require about 5
hours of post-mold cure.  It is not uncommon to transfer mold onto
multilayer LTCC SIP assemblies for RF modules.  The transfer mold process
applies about 1000 - 1400 psi (sorry not in Pa)to the fluid mold compound
for about 10 seconds.  It will inject into and through tiny gaps so perhaps
it would work for you.  Would a liquid encapsulant (glob top) be suitable?
Now, time for bed since it is now 1:22 AM here in California.


Best regards,
Leo

Director of Applications Engineering
ASAT, Inc.
3755 Capital of Texas Highway, Suite 100
Austin, Texas     78704

ph     512-383-4593
fx      512-383-1590
[log in to unmask]
www.asat.com


The information contained in this electronic message is CUSTOMER/SUPPLIER
PRIVILEGED AND CONFIDENTIAL INFORMATION intended only for the use of the
individual or entity named above. If the reader of this message is not the
intended recipient, you are hereby notified that any dissemination,
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you have received this communication in error, please immediately notify the
sender by electronic mail. Thank you.



-----Original Message-----
From: Ingemar Hernefjord (KC/EMW)
[mailto:[log in to unmask]]
Sent: Wednesday, February 02, 2005 2:56 AM
To: 'Leo Higgins'; 'TechNet E-Mail Forum'
Subject: RE: [TN] Plating on LCP/PPA Moulded devices


Hi Leo,
what instructive a lesson! You will never succeed as politician, because
you'll
explain in ten minutes what the party speakers elongate into hours. Anyway,
the
high temperature was an obstacle in my plan. The part to be LCP'd is a
ceramic
plate with a soldered metal part on, and the solder doesn't withstand more
than
200C. Hmm...I'll have to think a little.
Thanks again, I nominate hereby your mail as the best one for weeks.
Regards
Ingemar
PS. You seem to be working very early in the morning! He-he..

-----Original Message-----
From: Leo Higgins [mailto:[log in to unmask]]
Sent: den 2 februari 2005 09:23
To: Ingemar Hernefjord (KC/EMW); 'TechNet E-Mail Forum'; Leo Higgins
Subject: RE: [TN] Plating on LCP/PPA Moulded devices


Hello Ingemar,
     I do not know the actual viscosity of typical LCP materials.  Typical
LCP systems have a very small temperature range where the materials exhibit
the softening behavior from a rigid material to a high viscosity taffy-like
material (thermoplastic range) that will be injection moldable under high
pressure.  Above this short temperature range (perhaps only 5-10 degrees
Celsius), the LCP shows a very rapid drop in viscosity, much like the
melting of a crystalline material like a metal.  The temperature at which
this occurs is commonly above 300C, and may be above 400C for some special
materials.  In this liquid, highly fluid, low viscosity state the LCP
molecules remain highly aligned and the viscosity is very low, almost like
water.  The LCPs commonly exhibit shear-thinning, so with high pressure and
flow through narrow gaps, the local viscosity of material in the narrow gap
regions will drop even further.  This molecular alignment with flow
direction results in typical LCP systems being highly anisotropic.  The CTE
in the flow direction is much lower than the CTE transverse to the flow
direction because there is very little molecular bonding transverse to the
flow direction.  So the modulus is also lower when measured perpendicular to
the flow direction.  Due to the highly ordered LCP structure and presence of
almost no secondary amorphous phase, the LCP shows very low free volume
reduction or shrinkage when cooled. So the dimensions of the molded unit are
much more dependent upon the accuracy of the mold than with just about any
other thermoplastic.  The very low viscosity allows very fine features to be
moldable with LCP, so if you have a 5 micrometer wide and deep scratch in
the surface of the mold, you will see a 5 micrometer wide and high raised
ridge on the surface of the molded unit when removed from the mold.  Typical
thermoplastics (e.g. nylon) have a degree of "crystallinity" at the use
environment temperature, but are highly amorphous and viscous at the molding
temperature, although some degree of molecular alignment with flow direction
will occur.  These materials typically requires use of fairly high mold
pressure.  Since the LCP requires such high temperature injection molding,
the molds are generally heated with hot oil, not the hot water possible with
lower temp thermoplastic molding.  Since the molds are typically held at a
much lower temperature than the temperature in the mold screw injection
region (typically 300 to 400C), the LCP is rapidly injected into the mold
because the temperature range from very fluid (say at 360C) to solid may
only be 5 or 10C as mentioned above.  this rapid solidification allow short
cycle times between mold shoots.  Due to the anisotropy of the LCP during
molding and at room temp, the mold must be carefully designed relative to
location of injection point and mold cavity venting. LCPs are very
interesting materials, and they show the lowest permeability of virtually
any commercial polymers, offering the opportunity to form quasi-hermetic
structures, assuming the premolded package is well sealed.

This may be more info than you wanted, but it came out stream of
consciousness....


Best regards,
Leo

Director of Applications Engineering
ASAT, Inc.
3755 Capital of Texas Highway, Suite 100
Austin, Texas     78704

ph     512-383-4593
fx      512-383-1590
[log in to unmask]
www.asat.com


The information contained in this electronic message is CUSTOMER/SUPPLIER
PRIVILEGED AND CONFIDENTIAL INFORMATION intended only for the use of the
individual or entity named above. If the reader of this message is not the
intended recipient, you are hereby notified that any dissemination,
distribution and copying of this communication is strictly prohibited. If
you have received this communication in error, please immediately notify the
sender by electronic mail. Thank you.



-----Original Message-----
From: Ingemar Hernefjord (KC/EMW)
[mailto:[log in to unmask]]
Sent: Wednesday, February 02, 2005 1:28 AM
To: 'TechNet E-Mail Forum'; 'Leo Higgins'
Subject: RE: [TN] Plating on LCP/PPA Moulded devices


What is lowest viscosity of LCP? Need low Mps, say 5-50 Mps, for getting
into small cracks. /Ingemar

-----Original Message-----
From: TechNet [mailto:[log in to unmask]]
Sent: den 1 februari 2005 20:23
To: [log in to unmask]
Subject: Re: [TN] Plating on LCP/PPA Moulded devices


While I was with Siemens, the group developing an injection molded LCP
package (Polymer Stud Grid Array) had perfected a process for direct plating
on filled LCP (surface and 0.100mm microvias through 0.350mm thick LCP over
5 years ago.  Surface metal adhesion was equal to or better than Cu adhesion
to dielectric in HDI build-up substrates.  Highly adherent surface
conductors as fine as 0.050mm lines and spaces were processed non
photolithographically using laser structuring of an immersion Sn layer which
was used as an in-situ mask for ammoniacal Cu etching.  The process die
require proprietary processing to make the Cu adhere directly to the LCP.
Plating was blister free.


Best regards,
Leo

Director of Applications Engineering
ASAT, Inc.
3755 Capital of Texas Highway, Suite 100
Austin, Texas     78704

ph     512-383-4593
fx      512-383-1590
[log in to unmask]
www.asat.com


The information contained in this electronic message is CUSTOMER/SUPPLIER
PRIVILEGED AND CONFIDENTIAL INFORMATION intended only for the use of the
individual or entity named above. If the reader of this message is not the
intended recipient, you are hereby notified that any dissemination,
distribution and copying of this communication is strictly prohibited. If
you have received this communication in error, please immediately notify the
sender by electronic mail. Thank you.



-----Original Message-----
From: Dennis Fritz [mailto:[log in to unmask]]
Sent: Tuesday, February 01, 2005 8:57 AM
To: [log in to unmask]
Subject: Re: [TN] Plating on LCP/PPA Moulded devices


In a message dated 2/1/2005 9:35:26 AM Eastern Standard Time,
[log in to unmask] writes:

Last  year we tried to plate copper through holes on LCP.   Blistered
everywhere, top surface, in holes.


LCP is interesting resin.  To plate electroless copper  with adhesion, it
needs a special adhesion promotion treatment - a lot different  from epoxy
glass.
I agree, if you just run it down a regular electroless copper  line, you
will
get the worst hole wall pull away you have ever seen.

Contact me off line for a copy of the cycle that MacDermid  recommends for
plating the shielding on LCP connector bodies.  The same  cycle works on LCP
core laminate, and I think would work on molded interconnect  devices.

Denny Fritz
MacDermid

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