TECHNET Archives

December 2008

TechNet@IPC.ORG

Options: Use Monospaced Font
Show Text Part by Default
Show All Mail Headers

Message: [<< First] [< Prev] [Next >] [Last >>]
Topic: [<< First] [< Prev] [Next >] [Last >>]
Author: [<< First] [< Prev] [Next >] [Last >>]

Print Reply
Subject:
From:
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Andy Ng <[log in to unmask]>
Date:
Mon, 1 Dec 2008 15:17:20 -0800
Content-Type:
text/plain
Parts/Attachments:
text/plain (91 lines)
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
-----------------------------------------------------

ATOM RSS1 RSS2