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Subject:
From:
Steve Gregory <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Steve Gregory <[log in to unmask]>
Date:
Mon, 28 Aug 2017 16:11:30 -0600
Content-Type:
text/plain
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text/plain (177 lines)
Hi Steve,

Sorry it's taken me so long to get you pictures posted, but I had to sort
out some issues with the software for my web page. Windows 10 and all it's
updates made things a little difficult for a while, but I've gotten things
straightened out now. Here are your photos:

http://stevezeva.homestead.com/partial_ball_thumb.jpg

http://stevezeva.homestead.com/dull_solder.jpg

http://stevezeva.homestead.com/Head_in_pillow_1.jpg

http://stevezeva.homestead.com/Head_in_pillow_2.jpg

To be honest, I'll have to take your word for it but I couldn't see any
flux residues in your photo. They must be there, I just can't see them. May
I ask how thick the stencil is that you're printing the paste with? Just
curious is all. Also, who makes the connector?

Steve


On Mon, Aug 28, 2017 at 7:50 AM, Steven Kelly <[log in to unmask]> wrote:

> Thanks Steve for posting these for me.
> The first picture called partial ball is a picture of one of the balls on
> the connector as received.
> Second picture is what  the supplier has called dried flux on the
> connector as received
> Third picture shows what we call head in pillow
> Fourth picture - different view of third picture
>
> Thanks for everyone's help on this . Regards Steve Kelly
>
>
> -----Original Message-----
> From: Ed Popielarski [mailto:[log in to unmask]]
> Sent: August-25-17 2:26 PM
> To: TechNet E-Mail Forum <[log in to unmask]>; Steven Kelly <
> [log in to unmask]>
> Cc: Steve Gregory <[log in to unmask]>
> Subject: RE: [TN] Dried flux
>
> Steve Gregory (cc'ed herein) has graciously offered his time and dataspace
> to post Technet pix on his site.
>
> Forward your pics to Steve, I'm certain he will oblige!
>
> Regards,
>
> Ed Popielarski
> Engineering Manager
>
>
>                                970 NE 21st Ct.
>                               Oak Harbor, Wa. 98277
>
>                               Ph: 360-675-1322
>                               Fx: 206-624-0695
>                               Cl: 360-544-2289
>
>
>
>        “It's one kind of victory to slay a beast, move a mountain, and
> cross a chasm, but it's another kind altogether to realize that the beast,
> the mountain, and the chasm were of your own design.”
> https://goo.gl/maps/mMjg43rXeFB2
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Kelly
> Sent: Friday, August 25, 2017 11:13 AM
> To: [log in to unmask]
> Subject: Re: [TN] Dried flux
>
> Hi all,
> Want to post some pictures - can someone please give me direction. Thanks.
> Steve Kelly
>
> -----Original Message-----
> From: Bev Christian [mailto:[log in to unmask]]
> Sent: August-25-17 11:00 AM
> To: 'TechNet E-Mail Forum' <[log in to unmask]>; Steven Kelly <
> [log in to unmask]>
> Subject: RE: [TN] Dried flux
>
> Steve,
> From what people are saying, it is more and more likely that it IS the
> flux residue.  You say: "On average we are getting 1-3 failures per 200
> joints."  That pretty well eliminates gross part warpage.
>
> Minor point of interest:
> With regards to part warpage (or boards), they can test fine for planarity
> both before and after reflow. That doesn't mean they weren't warped DURING
> reflow.
> Bev
>
> -----Original Message-----
> From: TechNet [mailto:[log in to unmask]] On Behalf Of Steven Kelly
> Sent: Friday, August 25, 2017 10:26 AM
> To: [log in to unmask]
> Subject: Re: [TN] Dried flux
>
> Hi Dave,
> The parts come vacuum sealed and after opening we have a fairly short
> period of time to assemble. Manufacturer also said the “dull ball” on the
> connector is common for lead-free solder ( agree) and is not considered
> related to the failure. Its’ mainly because tin constituent appears on the
> surface. ( I understand that) Then they say the “residue” which we
> identified on the ball is considered to be flux and is not related to the
> head in pillow.
> But only a few of the 200 or so balls exhibit this issue and I am not
> saying we do not have other issues but we have traced some of the head in
> pillow to a couple of the so-called flux residue balls . On average we are
> getting 1-3 failures per 200 joints.
> We have measured the flatness of the rigid stiffener – looks OK to us –
> co-planarity is .002- .004 after convection reflow.
> Reviewing what Bev said yesterday- pasting – we looked at it 3 times but
> doing it again.
> I also have pictures of what we call an incomplete ball which I would like
> to post but I need a refresher course on how to do this.
>
> Thanks for everyone’s help.
> Steve Kelly
>
> From: David Hillman [mailto:[log in to unmask]]
> Sent: August-25-17 10:06 AM
> To: TechNet E-Mail Forum <[log in to unmask]>; Steven Kelly <
> [log in to unmask]>
> Subject: Re: [TN] Dried flux
>
> Hi Steve - We use a number of "bga style" connectors where there is a
> solder charge/preform on the connector which is designed to combine with
> the solder paste deposit creating sufficient solder volume and good solder
> joint integrity. I am not familiar with the having these types of
> connectors with "dried flux" - flux has a shelf life so the manufacturer's
> comment doesn't make much sense. From a practical point, the flux in the
> solder paste deposit is doing the bulk of the oxide scrubbing action so
> dried flux contribution is most likely a moot point. But - the fact that
> the manufacturer did not acknowledge the possible shelf life issue is
> dis-concerning.
>
> Dave Hillman
> Rockwell Collins
> [log in to unmask]<mailto:[log in to unmask]
> >
>
> On Thu, Aug 24, 2017 at 1:11 PM, Steven Kelly <[log in to unmask]<mailto:
> [log in to unmask]>> wrote:
> Hi All,
> I have a new hi-density BGA connector I am trying to assemble. When the
> supplier makes the connector they "solder balls onto the pin" (lead free).
> We see dried flux on the balls and when we solder the connector we are
> getting a few joints with head in pillow. The connector manufacturer says
> the dried flux is not an issue - is this true? Thanks. Steve Kelly
>
>
>


-- 
Steve Gregory
Kimco Design and Manufacturing
Process Engineer
(208) 322-0500 Ext. -3133

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