The not-to-solder I/O will touch the PWB solder pad ,  so what's the
meaning with not-to-be-soldered?
Yes, I am stupid.
Ing


On 19 April 2013 18:15, Steve Gregory <[log in to unmask]> wrote:

> Hi Ben,
>
> Actually, it was from the COO. Here's his response:
>
>         "Hi Steve,
>         Thanks for calling and sending the email.  We don't have a
> document that specifically calls out the recommended solder paste
> footprint, however, I am attaching a solder paste view from one of our
> development products - we've built a bunch of these so it is    quite
> robust.  As you will notice, there is no paste under the part, only on
> the lead fingers.  Let me know if you need anything else from us."
>
> Also I was sent a *.pdf of the solder paste layer of their development
> board that shows they don't print solder paste for the center pad:
>
> http://stevezeva.homestead.com/QF1D512_toppaste.pdf
>
> This was the first time I've run across a situation like this. But I
> guess there's a first time for everything I guess...
>
> Steve Gregory
> Process Engineer
> Kimco Design and Manufacturing
> 652 N. Five Mile Road
> Boise, ID 83713
> (208) 322-0500 Ext. 3133
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Gumpert, Ben
> Sent: Friday, April 19, 2013 9:39 AM
> To: [log in to unmask]
> Subject: Re: [TN] QuickFilter 16-pin VQFN
>
> Steve,
>
> I seem to remember seeing something about it not being required to
> solder the center pad on some other QFNs, but I don't recall being told
> not to.
>
> Makes me wonder if you were talking to a designer that didn't want the
> pad connected electrically, but doesn't really understand the soldering
> process (or reliability).
>
> Ben
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Joyce Koo
> Sent: Friday, April 19, 2013 11:22 AM
> To: [log in to unmask]
> Subject: EXTERNAL: Re: [TN] QuickFilter 16-pin VQFN
>
> Customer part with small qty you might have to be - non standard.  But
> the design sign off on the non-std and need to be prove using rel test +
> function test - nothing like antenna type or ground bouce, data it is
> OK.  Normally prototype stuff.  Hopefully, the leadframe is covered with
> solder (not exposed copper ground).  Normally, QFN is high frequency or
> high power device, ground is essential for thermal and function, but
> yours might be different.  (non thermal, low frequency).  My 2 cents.
>
> Joyce Koo
> Researcher
> Materials Interconnect Lab
> Office: (519) 888-7465 79945
> BlackBerry: (226) 220-4760
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
> Sent: Friday, April 19, 2013 11:09 AM
> To: [log in to unmask]
> Subject: [TN] QuickFilter 16-pin VQFN
>
> Good morning all,
>
>
>
> I've been looking at a board that we will be building in several weeks,
> and one of the packages on the is a 16-pin VQFN. Part number is:
> QF1D512-QN-T. Datasheet is here:
>
>
>
> http://www.quickfiltertech.com/files/QF1D512%20SavFIRe%20Datasheet%20A15
> .pdf
>
>
>
> I always check the datasheet to look at the recommended solder paste
> footprint to ensure that the stencil I spec out falls within the
> manufacturers recommendations. Yeah I know that sometimes the
> manufacturers footprint doesn't always work, but I look at it anyway for
> a sanity check.
>
>
>
> Well, the datasheet doesn't have one, and I sent a contact email to
> QuickFilter asking if they had a recommended solder paste footprint for
> this part and didn't receive a reply, so I called them the next day.
> When I spoke with them I was told that they didn't have a documented
> footprint for the part, but there was one thing they wanted me to know,
> which was to NOT print solder paste for the center pad beneath the part.
> "But why?" I asked, "there's a pad there in the drawing of the part...".
> I was told that the pad is completely non-functional, and the reason
> that it's there is because they didn't want to have to come up with a
> custom lead frame for this part, and this was the lead-frame that was
> "off-the-shelf" and what was used.
>
>
>
> Well, I was surprised! I mean this does make things easier for assembly
> by not having to worry about soldering the center pad, but this is the
> first time I have ever ran across something like this. Have any of you
> ever run across this on any other QFN parts?
>
>
>
> Have a good Friday everybody!
>
>
>
> Steve Gregory
>
> Process Engineer
>
> Kimco Design and Manufacturing
>
> 652 N. Five Mile Road
>
> Boise, ID 83713
>
> (208) 322-0500 Ext. 3133
>
>
>
>
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