TECHNET Archives

March 2010

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:
Bob Landman <[log in to unmask]>
Reply To:
Bob Landman <[log in to unmask]>
Date:
Wed, 3 Mar 2010 18:06:54 -0500
Content-Type:
text/plain
Parts/Attachments:
text/plain (204 lines)
I agree Bob.  I assume these are bypass caps?  Normally, we use .001uF, .01uF, .1uF in parallel but only on the power supply pins (each cap has a frequency range that it's effective impedance is very low hence it's a good bypass).  

I can't say I've ever seen a part with this many pins that needed bypassing.  Since the power and ground are on inner planes of the board, putting the caps very close to the part works fine for us.  We've never tried to get them on top of the pins.  Does it make that much of a difference in practice?

Your mileage may vary :-)

Bob Landman
H&L Instruments, LLC
 

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Robert Kondner
Sent: Wednesday, March 03, 2010 12:31 PM
To: [log in to unmask]
Subject: Re: [TN] Unusual Assembly Requirement...

Hi,

 If there is board space within a 2 or 3 inch radius and you have planes for these voltages (I assume they are on planes) the mounting caps one on top of each other is not required. 

 Even in a BGA you have little itty bitty bonding wires with more inductance that a couple inches of plane. Take you highest power frequency and compute the wavelength. Then take that frequency and calculate the inductance of 3mm of trace length. Using the wavelength / 10 of the board, plane impedance and the Z of the caps you will find stacking just does not buy anything. 

Bob Kondner

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Guy Ramsey
Sent: Wednesday, March 03, 2010 11:43 AM
To: [log in to unmask]
Subject: Re: [TN] Unusual Assembly Requirement...

We did the board in two reflow cycles. 
Print, place, dispense, place reflow. 
Dispense, place, dispense place reflow.

A three high stack is more common, one reflow.

Just make sure the convection fans are on low, and the parts are very solderable to start. 
A tombstone or drawbridge ruins your whole day. 

Though the speed is a few Ghz the devise on the opposite side of the board is digital.

Remember when we used to think a 10Mhz clock was really fast? 
I had a DELL 286 with 8 to 12.5 Mhz clock that, according to PC Mag, was fast enough to burn sand off the desert floor. 

Guy

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Victor Hernandez
Sent: Wednesday, March 03, 2010 6:09 AM
To: [log in to unmask]
Subject: Re: [TN] Unusual Assembly Requirement...

What was the total number of reflows?

Vic,

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Tuesday, March 02, 2010 2:39 PM
To: [log in to unmask]
Subject: Re: [TN] Unusual Assembly Requirement...

Hi Jon,

Yes these are individual caps, each layer is a different value. The board was screen printed and the bottom layer was machine placed. The next layer was done by hand dispensing solder paste on each cap termination, and then hand placing the second layer caps. The board was then reflowed. After reflow, paste was again hand dispensed on the second layer caps terminations, the third layer caps were hand placed, and then solder paste was hand dispensed on the third layer caps termination. Finally the fourth layer caps were hand placed, and the board sent back through reflow the second time.

We needed to do it in two reflow steps otherwise the stacks would have toppled over into each other...

Steve

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Roberts, Jon (SA-1)
Sent: Tuesday, March 02, 2010 3:04 PM
To: [log in to unmask]
Subject: Re: [TN] Unusual Assembly Requirement...

Steve, these were all individual caps? We have used double stack caps that were manufactured that way. It just looks fragile.  Jon

-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Steve Gregory
Sent: Tuesday, March 02, 2010 1:52 PM
To: [log in to unmask]
Subject: [TN] Unusual Assembly Requirement...

Hi All,

 

I came into work today and saw something that I've not seen before. Keep in mind that the area shown is about ½" square, and that these are 0402's...

 

http://stevezeva.homestead.com/files/Quad_Stack.JPG

 

This was done using two reflows, and the caps were not touched by a soldering iron. 

 

You may ask why. It's because it's what we were asked to do by our customer.

 

We have a very talented lady working on the production floor who accomplished this.

 

Steve


______________________________________________________________________
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
-----------------------------------------------------

This communication is intended only for use by the addressee(s) named herein and may contain business confidential and/or legally privileged information.
If you are not the intended recipient of this e-mail, you are hereby notified that any dissemination, distribution, disclosure or copying of this e-mail and its contents is strictly prohibited. If you have received this e-mail in error, kindly notify the sender by replying to this message. In addition, please permanently delete the message and any attachments without copying or disclosing the contents. Thank you for your cooperation.

THIS DOCUMENT AND/OR SHIPMENT MAY CONTAIN COMMODITY ITEMS, SOFTWARE OR TECHNICAL DATA THAT IS CONTROLLED BY U.S. EXPORT LAW, AND MAY NOT BE EXPORTED OUTSIDE THE UNITED STATES OR TO NON U.S. PERSONS WITHOUT THE APPROPRIATE EXPORT LICENSE FROM EITHER THE U.S. DEPARTMENT OF STATE OR DEPARTMENT OF COMMERCE.

______________________________________________________________________
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
-----------------------------------------------------


______________________________________________________________________
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
-----------------------------------------------------

______________________________________________________________________
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
-----------------------------------------------------


______________________________________________________________________
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
-----------------------------------------------------


______________________________________________________________________
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
-----------------------------------------------------



______________________________________________________________________
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
-----------------------------------------------------

ATOM RSS1 RSS2