TECHNET Archives

July 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:
Dwight Mattix <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Dwight Mattix <[log in to unmask]>
Date:
Thu, 10 Jul 2008 08:33:40 -0700
Content-Type:
text/plain
Parts/Attachments:
text/plain (140 lines)
<runs from the from screaming hysterically -- WHY do i do this for a living?>

At 08:05 AM 7/10/2008, you wrote:
>Just a few thoughts on inner layer shifting.
>
>1. Don't forget Pythagoras and the proverbial 
>True Hole Position - .001" misregistration in 
>the X and .001" in the Y can be .00141" at 45°. This concept
>     works with holes, pads and clearances etc.
>2. Consider that the drilled holes, ablated 
>holes and layers are all independently tooled 
>and shift independent of each other.
>3. Hole to hole registration can vary due to drill deflection, drill walk etc.
>4. Image feature to image feature may move due 
>to uneven expansion of the dielectric or the art 
>work. This uneven expansion may be due to physical
>    deformation or uneven thermal expansion.
>4. Sequential lamination adds the vagrancies of 
>layer shift by variation sublam to sublam registration.
>5. Back drill, counter bore and secondary drill 
>operation add another layer misregistration 
>particularly if the secondary drill is producing tooling
>    holes.
>6. Over-etch and under-etch can effect line 
>width and spacing that may appear to be a shift 
>in layer when in fact the issue is variation in feature size.
>7. Improper artwork compensation to accommodate 
>process variation can produce what appears to be 
>layer shift but in fact is improper sizing.
>8. Mixing materials, uneven builds, grain 
>direction (warp vs. weft) all can produce registration issues.
>9. Nonfunctional pads in every layer may 
>aggravate drill and image registration.
>10. Glass style and epoxy ratios may affect registration.
>11. Humidity can have an effect on artwork and image registration.
>12. Tooling methods, round alignment holes 
>verses slots, aligning in the center verses the 
>edge of panel will affect layer shift.
>
>To know if you have inner layer shift, I 
>believe, you need to consider possible causes of 
>misregistration. For example the inner layer may 
>not be shifted, it may be that the drilled holes 
>are shifted. You have to choose what you 
>consider to be you reference point, drill hole 
>or layer one image etc. and consider the registration to that.
>
>All that being said, reasonable etch back should 
>not have a significant role or be significantly 
>affected by, inner layers shifting.
>
>
>Paul Reid
>
>PWB Inc.
>
>
>
>-----Original Message-----
>From: TechNet [mailto:[log in to unmask]] On Behalf Of Kathy Kuhlow
>Sent: Wednesday, July 09, 2008 4:07 PM
>To: [log in to unmask]
>Subject: [TN] PCB Inner layer shifting
>
>I was just reading and got to thinking about PCB 
>inner layer shifting. Now I realize that this 
>can be caused by registration issues but here 
>are the questions I can't readily answer:
>
>1) Is it possible to cause inner layer shifting 
>on only signal layers during the assembly 
>operations or will this be seen in the PCB fabrication testing?
>
>2) Can inner layers that create opens or shorts 
>be latent or would the effect be seen immediately?
>3) Would inner layers that do shift all shift 
>the same way? In other words would I get the 
>same opens/shorts? What would be the proportion 
>of possible affected if not all?
>4) Would the PCB stresses caused by lamination 
>not be released prior to the PCB test or is 
>there enough residual stress still in the PCB at 
>time of assembly to cause an issue?
>5) How would you know if you have inner layer shifting?
>
>I was just reading about etch back and some the 
>test data related with the process, is this part 
>of the driver to develop this process?
>
>Kathy Kuhlow
>6980 Professional Parkway East
>Sarasota, FL 34240
>Phone: 941-907-1000 ext 8248
>Mobile: 320-267-5549
>Email: [log in to unmask]
>
>
>---------------------------------------------------
>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