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December 2008

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Subject:
From:
Rudolph yu <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Rudolph yu <[log in to unmask]>
Date:
Mon, 1 Dec 2008 23:51:37 +0000
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Hi Andy:
 
In theory, I think the Panasonic SP18 should be able to achieve 1.66 cpk.  But the data that we collected is not pointing to that..
One reason I think is due to the outliners that we are having difficulties to remove from the calculation. (using the software that comes with the SPI machine)
 
I was just reading couple papers on the internet, and people are using +/-50% USL/LSL for their experiments. I just wish I could find some literature that says 50% is the industrial standards.  If I feel more comfortable to set the process control limits at +/- 25%. 
 
Rudolph 
 
 
 
 
 
 
 
> Date: Mon, 1 Dec 2008 15:17:20 -0800> From: [log in to unmask]> Subject: Re: [TN] What are the industrial standards for Solder paste printing limits?> To: [log in to unmask]> > Hi Rudolph,> > What's your mean and std dev? With 5 mils thickness for 50% tolerance, > the USL would be 7.5 mils and LSL is 2.5 mils. This tolerance is a bit > too high. I think 25% is a more reasonable tolerance, unless there are > no-loads that you're taping with tape on the stencil. This will create > a larger gap, and thus much thicker deposits. Even with 25%, you > should be able to get process cap index of 1.66 across 6 std deviations.> > Andy> > > >> > -----Original Message-----> > From: TechNet [mailto:[log in to unmask]] On Behalf Of Rudolph yu> > Sent: Monday, December 01, 2008 3:52 PM> > To: [log in to unmask]> > Subject: [TN] What are the industrial standards for Solder paste printing> > limits?> >> > Hi Technetees:> >> > One of our customers had asked us to show that our solder paste despoisition> > process is capable to acheive Cpk at 1.66 (6 sigma). We just built a> > thousands of pilot boards, and the SPC report I got from the TRI's SPI> > machine indicated that the process is able to reach that goal.......however> > the software sets the upper limit and lower limits for height, area and> > volumn to about +/-50%. Is this reasonable to have such a high variance in> > the printing process? (We use 5 mil stencil with 0201 and fine picthc> > aperature). If I change the limits to +/- 25%, the Cpk will become around> > 1.33 ( 4 sigma)...should I claims that we can acheive 1.66, and point out> > that the wide tolerence was set by the machine expert, or should I limit> > the tolerance spread, and hope that customer will accept lower Cpk.> >> >> > I guess my quesiton is " Is +/- 50% tolerance a resonable limits for paste> > printing process?"> >> >> >> > BTW the AOI and AXI yield is in the high 98 and low 99 range for this> > design.> >> > Thanks> > Rudolph> >> >> > _________________________________________________________________> > Proud to be a PC? Show the world. Download the "I'm a PC" Messenger> > themepack now.> > hthttp://clk.atdmt.com/MRT/go/119642558/direct/01/> > ---------------------------------------------------> > Technet Mail List provided as a service by IPC using LISTSERV 15.0> > To unsubscribe, send a message to [log in to unmask] with following text in> > the BODY (NOT the subject field): SIGNOFF Technet> > To temporarily halt or (re-start) delivery of Technet send e-mail to> > [log in to unmask]: SET Technet NOMAIL or (MAIL)> > To receive ONE mailing per day of all the posts: send e-mail to> > [log in to unmask]: SET Technet Digest> > Search the archives of previous posts at: http://listserv.ipc.org/archives> > Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16> > for additional information, or contact Keach Sasamori at [log in to unmask] or> > 847-615-7100 ext.2815> > -----------------------------------------------------> >> > ---------------------------------------------------> > Technet Mail List provided as a service by IPC using LISTSERV 15.0> > To unsubscribe, send a message to [log in to unmask] with following text in> > the BODY (NOT the subject field): SIGNOFF Technet> > To temporarily halt or (re-start) delivery of Technet send e-mail to > > [log in to unmask]: SET Technet NOMAIL or (MAIL)> > To receive ONE mailing per day of all the posts: send e-mail to > > [log in to unmask]: SET Technet Digest> > Search the archives of previous posts at: http://listserv.ipc.org/archives> > Please visit IPC web site > > http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional > > information, or contact Keach Sasamori at [log in to unmask] or > > 847-615-7100 ext.2815> > -----------------------------------------------------> >> > ---------------------------------------------------> Technet Mail List provided as a service by IPC using LISTSERV 15.0> To unsubscribe, send a message to [log in to unmask] with following text in> the BODY (NOT the subject field): SIGNOFF Technet> To temporarily halt or (re-start) delivery of Technet send e-mail to [log in to unmask]: SET Technet NOMAIL or (MAIL)> To receive ONE mailing per day of all the posts: send e-mail to [log in to unmask]: SET Technet Digest> Search the archives of previous posts at: http://listserv.ipc.org/archives> Please visit IPC web site http://www.ipc.org/contentpage.asp?Pageid=4.3.16 for additional information, or contact Keach Sasamori at [log in to unmask] or 847-615-7100 ext.2815> -----------------------------------------------------
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