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Tantalum capacitor mis-alignment & throwoff issues

Tantalum capacitor mis-alignment & throwoff issues

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Hi Team, We using one of tanatalum capacitor ( vishay) fo... - Dec 20, 2018 by Prem

Hi Prem, OK... Is it definitely ok before the oven, as... - Dec 20, 2018 by Robl

Once a long time ago I had a board where the cap beside a ta... - Dec 20, 2018 by Stephen

Hi Robl, Thanks for quick reply , I want to see you m... - Dec 25, 2018 by Prem

Hi, Can some one reply for my query please ?? Thank... - Dec 26, 2018 by Prem

Hi Prem, it will really help if you provide more pictures... - Dec 27, 2018 by Evtimov

Hi Prem, try take a few caps and bake them before assembling... - Jan 08, 2019 by Ken

Prem

#81625

Tantalum capacitor mis-alignment & throwoff issues | 20 December, 2018

Hi Team,

We using one of tanatalum capacitor ( vishay) for many models , in this we facing mis-alignment & throwoff issues after post reflow stage. After my analysis,my suspection is that due to one side part termination design ( square cut) issues & when i asked vishay , they told its designed for showing polarity purpose , when i compared to other supplier like kemet, panasonic ,etc , im not seeing such designs & we not facing any alignment issues in our line.

Can anyone support , whether this cause is right ?? I dont know how to attach picture here , if so i can attach the data sheet - MPN is T55V157M010C0015

Thanks Prem

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Robl

#81626

Tantalum capacitor mis-alignment & throwoff issues | 20 December, 2018

Hi Prem,

OK...

Is it definitely ok before the oven, as it's a big part to move. Never had an issue with them.

Has the part got the correct z height on or is the paste being displaced on placement

What machine are you placing it with (is it laser vision or camera)

Are you slowing the travel speed of the head down on placement or is it running same speed as normal parts?

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Stephen

#81631

Tantalum capacitor mis-alignment & throwoff issues | 20 December, 2018

Once a long time ago I had a board where the cap beside a tantalum shifted in the oven. I phoned our HQ plant and was told that they had the same issue and that it was the tantalum capacitor outgassing. We just applied a dot of glue to the cap. Try baking a few of the caps before reflowing them.

But if it turns out to be because of pad layout then a lot of times it helps to have stencil apertures split in two to balance forces.

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Prem

#81651

Tantalum capacitor mis-alignment & throwoff issues | 25 December, 2018

Hi Robl,

Thanks for quick reply , I want to see you my attachment first ( forgot to attach in my first share ) .As i said earlier ,Im suspecting termination design made by vishay & I never seen these kind of design from other alternate vendors which we are not facing any alignment issues.

Attachments:

tantalum termination design ( one side).jpg

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Prem

#81653

Tantalum capacitor mis-alignment & throwoff issues | 26 December, 2018

Hi,

Can some one reply for my query please ??

Thanks Prem

reply »

Evtimov

#81655

Tantalum capacitor mis-alignment & throwoff issues | 27 December, 2018

Hi Prem,

it will really help if you provide more pictures and metrics. Pad layout, part datasheet, stencil design and most of all picture of the misplaced part on the board. This looks like a very interesting case and I am willing to help you, but the facts that you provide are insufficient. Help us to help you. Regards, Emil

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Ken

#81713

Tantalum capacitor mis-alignment & throwoff issues | 8 January, 2019

Hi Prem, try take a few caps and bake them before assembling them to the board to see whether this problem goes away. Its a common problem these tentalum caps can outgas if there's moisture trapped within.

Once verified that moisture is the culprit, you can explore in sourcing this caps in MSD bags *you can remove the caps from T&R and bake in oven at 125DegC for 4 hours.

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