Hi, On one of my PCBs i'm using a heavy IC. It is a 70pin gull wing package. And, the problem is that the pins are breaking near the IC package. I don't want to use RTV, as it's difficult to remove. What best I can do to protect this against vibration tests?
Thanks and Regards, Veeresh
If the board is close to a panel of some sort them you could use that thermally conductive matting stuff between the PCB and the panel that also acts as a vibration absorber.
Got a link to the actual package?
Vibration tests are done for a reason, if it's failing then you have trouble. Do you just want to a) pass the test (as you seem be to implying), or b) do you want to pass the test and make your product more reliable?
Dave.
Can you link to a package drawing?
Best regards, Spehro Pefhany
-- "it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
The breaking is often caused by the PCB flexing. During the vibration test, the vibration may hit a resonant frequency for the PCB. Adding another attachment point ot the PCB can help.
Placing a rubber foot such that the PCB bumps into it if it deflects, will often help to damp a resonance.
Changing details of the mounting will often help. Basically, you want to push the resonant frequency up and increase losses. It matters less how you do this than that it is done.
Or going to a thicker PC, or attaching stiffeners to the PC -- One of these will be the least expensive for you, but it depends on your situation.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/ Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html
I think I would want to make my product better, and pass vibration tests as a consequence, rather than being focused on passing the tests and damn what happens to my product in the field.
-- Tim Wescott Wescott Design Services http://www.wescottdesign.com Posting from Google? See http://cfaj.freeshell.org/google/ Do you need to implement control loops in software? "Applied Control Theory for Embedded Systems" gives you just what it says. See details at http://www.wescottdesign.com/actfes/actfes.html
Rubber mounts on the pcb should reduce it.
As others have mentioned, it's flex resonances of the board itself that are probably the problem. Boards will blur at resonance, and literally throw parts off. The board should be stiffened, damped, or vibration isolated.
John
Hello Sir, Thanks for the kind response from all of you.
It has passed the tests some times. But when tested for many times, the pins break. I want to make it rugged... exactly option (b) :-) The PCB is housed in an enclosure with screws at every 5cm w.r.t each other. Please check the link below for package diagram.
please consider the data sheet of BU-61580(second one ). I'm using the gull wing package - page 44 of 46. I took this perticularly to save the space. Now, I've kept a sil pad below the device, super glue on four corners, and RTV on pins. Is this fine, or something better can be done?
Regards, Veeresh
I think I can fill upto 1 inch to reach the top plate, using sil pad. ~Veeresh
or
Hello Sir, What can we use for this vibration isolation? Is it some kind of washers, and studs that we use to fix the board in the box? ~veeresh
please consider the link below
please consider the link below
please consider the link below. Sorry for inconvinience.
please consider the link below. Sorry for inconvinience.
US$ 1000 :-)
actually they suggested putting glue on the pins, and all. But once glue is put, the maintainance will be diffiult
Why don't you tell us
Google "vibration isolator". The classic vendor for this stuff is at lord.com.
John
Have you considered asking the manufacturer? Why don't you tell us how much it costs so Joerg can have a heart attack? Last part I used from that company was in the high four digits (USD).
Best regards, Spehro Pefhany
-- "it\'s the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
That's a lot of Sil-Pad dude, and it ain't cheap. There are much easier ways to solve your problem.
Dave.
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