Ellsworth,
I'm Happy to help Happy out on this one. A small faux paux in
his spelling, what he meant was "calendered":
calendered
Calender \Cal"en*der\, v. i. [imp. & p. p. Calendered; p. pr. & vb. n.
Calendering.] [Cf. F. calandrer. See Calender, n.] To press between
rollers for the purpose of making smooth and glossy, or wavy, as woolen
and silk stuffs, linens, paper, etc. --Ure.
HTH,
Mike
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Ellsworth Berkowitz
Sent: Tuesday, December 16, 2003 8:46 AM
To: [log in to unmask]
Subject: Re: [TN] .5 mm pitch components
I volunteer to ask the "dumb" question.
Mr. Holden, could you please define the term "cullender" as used in your
email? I am unfamiliar with this term in regards to pc board
processing.
However, when it comes to pasta, I can wield a mean colander.
Thank you.
Ellsworth D. Berkowitz, P.E.
Paradyne Networks LLC
www.paradyne.com
On Mon, 15 Dec 2003 12:54:41 -0500, Happy Holden <[log in to unmask]> wrote:
>Chris,
>These are really assembly questions and can be complex trade-offs. It
>all depends on who is doing the assembly. We find a large soldermask
>window around each row of pads easiest, but that might not match the
>assembly capability. All types are ordered. There is also an issue of
>where the 0.5mm devices are placed if the panel is large. FR-4 moves
>with any heat cycle in assembly and the solder paste may end up between
>the pads. For this reason, customers have us put the solder paste on
>the board, reflow it, clean it and then cullender it so the solder is
>flat. All they have to do is flux, place the parts and reflow.
>
>There is no bottom to the pitch that might require solder mask. We do
>a lot of flip chip packages that are 0.2mm pitch with SM opening that
>0.114
>+/- 0.01mm for SM defined pads. We have experimental boards now that
>+are
>0.152mm pitch and require soldermask.
>Its not our job to force an assembler into something he doesn't want,
>but rather, to give them the price alternatives of what is available
>and let them figure out the SYSTEM COSTS.
>
>Happy Holden
>Westwood Associates
>
>
>
>
>
>Chris Robertson <[log in to unmask]>
>Sent by: TechNet <[log in to unmask]>
>12/15/2003 11:33 AM
>Please respond to Chris Robertson
>
>
> To: [log in to unmask]
> cc:
> Subject: Re: [TN] .5 mm pitch components
>
>
>Happy,
>What is your recommendation if someone doesn't want to pay the premium
>price for a manufacturer that can't hold that?
>Are you an advocate for the all mask or none approach? This is the
feeling
>that the cost outweighs the fallout from bridging?
>This isn't a trick question. I just know people that have a block of
>mask clearance and others that feel that the fallout from that is to
>costly.
>Is there a breaking value? I mean is there a pitch that you hit that
>almost MUST
>require masking?
>
>Chris Robertson
>[log in to unmask]
>
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