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SN74LS244: SN74LS44

Eric Uneken
Prodigy 10 points
Part Number: SN74LS244
Other Parts Discussed in Thread: CD54ACT244

Regarding problems we have with part SN74LS244N I send you this e-mail. The problem is:

We have soldering problems with article SN74LS244N (our ITI-00047). Our qualtiy depatment states:

 As you can see on the attached pictures the legs do not solder properly or not. The cause is according to Variass the alloy (NIPDAU?) of the leg. We've been seeing this problem for a few years now and it seems to be getting worse. We see this problem with both wave soldering machines and selective soldering machines (two different processes). Our soldering processes are within specifications and that is not the cause. Using extra flux helps a bit, but is not the solution, hand soldering only requires "burning" for quite a long time. Another brand of ICs with a different alloy solders without any problems.

We would like to know the following from you:

* What can we do to properly machine solder the ICs?
* Is this a known problem (we are undoubtedly not the only ones with this complaint)?
* Is there an alternative to this component with a solderable alloy?

Please provide your response to this.

Saskia de Wit

AMR-8222.zip

  • 0
    TI__Mastermind 19400 points

    Hi Saskia,

    Granted, I've only been working here for about 8 months, but in that timeframe I don't recall any complaints about difficulty soldering any of our devices. I'd try referring to here for a wave solder profile just to double check that it's in spec:

    AN-2029 Handling and Process Recommendations (Rev. H)

    All of our PDIP packages for these devices and similar seem to have NIPDAU leadframes (which is not to say that NIPDAU is not a "solderable alloy" because frankly millions of people are using this alloy without issue). We have a CDIP package for a similar device (the CD54ACT244) with Tin-Lead leadframes which you can try if you really want to, however that package is vastly more expensive. 

    More flux typically is the solution, but that's about the only thing left that I can really suggest. 

    Best,

    Malcolm

  • 0
    Guru 279000 points

    In theory, NiPdAu is not prone to being tarnished. But were these devices stored for a long time, or with high moisture exposure?