Graham,
While I have not tried this clever device, it seems like a good way to solve the problem.
See http://www.autosplice.com/solderball-pins/
"Eliminates Coplanarity Concerns When Soldering Parallel PC Boards
Packaged in Tape Reel for use with standard feeders for automated placement. The product contains a Solderball that maintains its shape during multiple solder reflow processes. The PC board or device can then easily be soldered to pads on another parallel PC board. The Solderball pins accommodate up to .020" (0.5mm) coplanarity variation with high current reliability."
Bob Landman
H&L Instruments, LLC
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Graham Collins
Sent: Tuesday, March 23, 2010 8:45 AM
To: [log in to unmask]
Subject: Re: [TN] TI/Emerson SMT Board Mounted Power
Hi Russell
Is it skewed before it goes into the reflow oven? If yes, then a placement issue. If it looks OK before reflow oven and is skewed after the reflow oven then obviously is moving in there - which points to a pad size problem.
If their placement is good and it is skewing in the oven, one trick we have used in the past is to dispense a glue dot under the component body
- it will hold the alignment during reflow. We have used this method when pad layout is not quite right and the alignment is critical to meet IPC-A-610 requirements (e.g. for heel fillet). They would need to have glue dispense capability though.
regards,
- Graham
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Nowland, Russell Howard (Russell)
Sent: Monday, March 22, 2010 4:57 PM
To: [log in to unmask]
Subject: [TN] TI/Emerson SMT Board Mounted Power
Hello Technetters,
I have a problem I hope someone out there has a solution for.
I have on a PCA that uses a Texas Instrument/(Emerson Power/Artesyn) (dual sourced but part of the POLA) SMT board mounted power converter.
The MPN is PTH03050WAS. It is actually combination PTH and SMT. The device has 40 mil diameter pins for PTH and to make it SMT they simply add a donut (solder dam) on the pin and round the edges and call it a solder ball. I think the problem my EMS is having is really with pick-n-place because the pick-up point (Actually the top of a
transformer) is off-center, fairly small, and it has a plastic label on it.
The problem is the device is coming out of the oven skewed and violating IPC 610D. The pad diameter is exactly what is recommended by the datasheet (.085-inches). The TI datasheet recommended a 0.080-0.085 diameter aperture @ six mils. Originally my EMS had 0.085-inch @ 5 mils but changed the aperture to a bull's-eye shape with the thought the bull's-eye would help center the device. Both of the stencils have failed to draw the device to the center.
Because this is really a Butt Joint I am holding the EMS to no side overhang. This is causing them quite a headache. They have also not come up with a viable solution either.
Here is the link to the data sheet
http://www.emerson.com/sites/network_power/en-US/Products/Product_Detail
/Product1/Documents/PTH03050%20DC-DC%20Converter/PTH03050%20Data%20Sheet
.pdf
Has anybody used these devices with good results? If so can you share your methodology?
Thanks in advanced,
Russell Nowland
Alcatel-Lucent
Advanced Manufacturing Engineer
Address: 14000 Quail Spring Parkway, Suite 300 Oklahoma City, OK 73134
email:
[log in to unmask]<mailto:russell.nowland@alcatel-lucent
.com>
Desk: 405-302-1660
Cell: 405-203-0034
Fax: 405-302-1622
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