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WL1805MOD: Thermal dissipation considering power pads soldering

Florian H
Prodigy 30 points
Part Number: WL1805MOD

Hi,

I am using a WL1805 module on my board, and have some soldering process issues that cause voids on the power pads.

WL1805 datasheet provide the Thermal Resistance from junction to air; junction to board and junction to case. These values are assume to be correct in a good reference PCB with good solders.

How the thermal resistances evoluate when voids are present in the solder ? How can I estimate the product lifetime degradation ?

PS : the soldering is approximatively 50% of the power pad area. All design recommandation (copper area on the PCB) are respected.

Thank you for your feedback.

  • 0
    TI__Mastermind 20285 points
    Hi,
    I have assigned your query to our H/W lead.
    Please expect a follow up response later.
    BR,
    Eyal
  • 0 in reply to Eyal Reizer
    TI__Genius 12260 points
    Hi Florian.

    The requirement on the soldering coverage to maintain the lifetime we state in the datasheet is no more than 30% voiding. This is covered by IPC 7093. If the pads do not meet 70% coverage, then this may cause performance issues as you will not be able to dissipate the heat. In this case it is recommend that you review the vias under the part as well as adjusting your reflow profile to improve on this voiding. We do not recommend leaving the 50% void rate for production.

    I hop this helps.

    Thanks,
    Riz
  • 0 in reply to Rizwan Murji
    Prodigy 30 points
    Hi Rizwan,

    Thank you for the feedback, we are already working in process improvements.

    We use to base the acceptability criteria from IPC610. I just look at IPC7093 summary (I do not have it), it looks like a process guideline that we should follow, and we will.
    However, from my understanding, acceptability criteria are in the IPC610 and not in IPC7093. The ambiguity in IPC610 is that void criteria is specified for BGAs, not for LGA which are part of BTC component (many LGA manufacturers have their own interpretation for this point), we need to go further with our IPC expert to get the good interpretation.

    Thanks,
    Florian
  • 0 in reply to Florian H
    TI__Genius 12260 points
    Hi Florian,

    Thank you for the update. From our reliability team we want to ensure for proper heat dissipation as well as performance that we do not have more than 30% voiding on the pads. In-line with our previous statement.

    Thanks,
    Riz