Dale,

 Bunch of issues here. That deflection, are you talking a constant sag? If
so then additional board supports might be needed. 

 The machines sense board height and have various Z direction acceleration
profiles to speed down towards the board yet touch down slowly and deliver
the component with a specific force. This force will cause some board
deflection. If a component is extra thick the fast Z down can smack the
board and cause vibration problems. 

 In general you want your board supported so they give you a "Stiff"
placement platform. 

 Many parts have their contact areas pushed down into the paste all the way
to the PCB copper, this is good. Other parts sit on top the paste which can
cause squish of paste for small parts. Minimum placement forces are often
very high for small parts.

 What you can adjust for a given tool or given part type is what makes a big
difference in PnP software.

Bob Kondner

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Hart, Dale L CTR USAF
AFMC AFRL/RXSA
Sent: Monday, October 04, 2010 2:26 PM
To: [log in to unmask]
Subject: [TN] pick and place /board deflection

 

I was on the shop floor and noticed deflection in the 8x8 inch panel that
was being populated.  Would the deflection in the middle of the panel cause
components to sit higher on the paste and thus have a slightly higher solder
joint height than components on boards along the rails?       Thanks in
advance

 

Dale L. Hart

Universal Technology Corporation (UTC)

Failure Analysis

1270 North Fairfield Road

Dayton, Ohio  45432-2600

(937) 656-9165

Fax (937) 656-4600

Email:  <mailto:[log in to unmask]> [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
-----------------------------------------------------


______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please contact helpdesk at x2960 or [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
-----------------------------------------------------