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QFN Side fillet

Views: 3703

#83028

QFN Side fillet | 19 July, 2019

May I know what is the requirement for side fillet for QFN?Any information from IPC spec on QFN side fillet?We cant make the solder joint form at the side fillet.

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#83036

QFN Side fillet | 19 July, 2019

Double-check me on this, but I don't believe that A-610 [IPC-A-610] requires side fillets on QFN solder connections, because the sides of most terminations are not plated. Plating on the bottom of the termination is sufficient for a proper solder connection.

A-610 seems to be more concerned with proper alignment and voiding levels in QFNs than solder fillets.

Check the solderability of your components.

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#83037

QFN Side fillet | 19 July, 2019

Hi,

Are you referring to the condition illustrated here? ... https://www.semlab.com/qfn-solder-fillets

In this case, the solder was wicked down an attached un-filled PTH via.

Ed Hare SEM Lab, Inc.

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#83040

QFN Side fillet | 19 July, 2019

yes..there is no fillet as shown in the picture..

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#83041

QFN Side fillet | 19 July, 2019

Thanks Dave..What is the voids spec for QFN?This is another challenge with the QFN's

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#83043

QFN Side fillet | 20 July, 2019

IPC-A-610F 8.3.13 Bottom Termination Components (BTC)

...

Thermal plane void criteria shall be established between the manufacturer and user

IPC-A-610F, 8.3.14 Components with Bottom Thermal Plane Terminations

...

Thermal Plane Void Criteria - Acceptance criteria will need to be established between the manufacturer and user.

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#83046

QFN Side fillet | 22 July, 2019

some PQFN package configurations have no toe exposed or do not have a continous solderable surface on the exposed toe and a toe fillet will not form. (IPC-A-610F 8.3.13)

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#83050

QFN Side fillet | 22 July, 2019

While we're are it, here's a link to a recent FORUM thread that talk's about BTC standoff height: https://smtnet.com/Forums/index.cfm?fuseaction=view_thread&CFApp=1&Thread_ID=21852&mc=9

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#83113

QFN Side fillet | 1 August, 2019

Hi ,

hope below information may help you.

The presence of small voids in thermal pad region is not likely to result in degradation of thermal and electrical performance The combing of smaller multiple voids up to 50% of the thermal pad area, does not result in a lost in thermal performance Refer IPC 7093, clause 6.1.5.3 and 7.6.1

Regards, Ameen

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