Thanks Leo,
Didn't know that bit about hermeticity which is interesting.
I don't suppose you know why LCP has a reputation of being tricky to bond
to? Is it due to low surface energy or delamination of the LCP surface which
I have recently seen in some plating trials - the plating worked fine but
the material delaminated when an adhesion test was performed.
Regards,
Eric Christison
Mechanical Engineer
Consumer & Micro Group - Imaging Division
STMicroelectronics
33 Pinkhill
Edinburgh
EH12 7BF
Tel: +44 (0)131 336 6165
Fax: +44 (0)131 336 6001
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Leo Higgins
> Sent: Wednesday, February 02, 2005 8:23 AM
> To: [log in to unmask]
> 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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