Printed Circuit Board Assembly & PCB Design SMT Electronics Assembly Manufacturing Forum

Printed Circuit Board Assembly & PCB Design Forum

SMT electronics assembly manufacturing forum.


Tombstoning 0201

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Djo

#87052

Tombstoning 0201 | 10 September, 2021

Hello to all ,

Could you help with this defect .. Tombstoning 0201 , always at the same place in board , only this component near to the coax connector..with a defect rate of 2 % ..All the process is perfect . i cheked : stencil design , SPI result , component dimension , component wettability , reflow oven profile , component placement .. All is good.. nothing changes..Any ideas?

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#87053

Tombstoning 0201 | 11 September, 2021

Hi, check the Land pattern 0201 on the board, compare with another 0201. Could be different gap.,

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#87054

Tombstoning 0201 | 11 September, 2021

Most common causes of tombstoning in our factory: small amount of paste printed on the pcb, improper placement ( pick up process, picked up on the component metallization- large cavity in reel).

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#87055

Tombstoning 0201 | 13 September, 2021

A large pad nearby receives heat - the resistor pads heat up unevenly ?

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#87056

Tombstoning 0201 | 13 September, 2021

There may also be a problem with the a thermoprofile. Measure the temperature of both contacts of the component, if they heat up not evenly and the soldered lead heats up faster, then the problem is in the profile. To solve the problem of misalignment during placement, it is possible to change the design of the stencil by shifting the apertures towards the center of the component and increasing the area. Of course, within reasonable limits.

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#87057

Tombstoning 0201 | 13 September, 2021

Agree. The big pad and part nearby made the paste on two ends of cap melted unevenly.Deposit more paste on the tombstone-ed pad will make it easier to melt. Nothing wrong with profile if everything else is OK. BTW, how to measure temperature on two ends of 0201 part as someone recommended.

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#87062

Tombstoning 0201 | 14 September, 2021

To measure two 0201 pads, you need to solder two thermocouples for each component pin on different segments. Thermocouple wire should be 36AWG.

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DWL

#87065

Tombstoning 0201 | 14 September, 2021

Just for grins, try rotating the board 180 degrees before reflow. this might allow both sides of the part to reflow at the same time.

Is it just that one part with the arrow? Its interesting that none of the other parts have the same issue despite appearing to have the same foot print and thermal load. The only difference is the angle of the pattern.

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