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MC33078: MC33078DR (SOIC) soldering conditions

user1225438
Prodigy 20 points
Part Number: MC33078

Is hand soldering with a soldering iron recommended for the MC33078DR (SOIC)?

If so, are there any conditions?

・Upper limit of solder temperature
・Upper limit of heating time
・Maximum number of times
·etc

  • 0
    TI__Guru* 76831 points

    Hi ,

    Is hand soldering with a soldering iron recommended for the MC33078DR (SOIC)?

    Yes, you can hand solder the part without any issues. In fact, you can control temperature and soldering time way better than other production method. If you concerned about soldering temperature, you may use Pb-Sn solder, and select a proper soldering iron temperature (~400F or 204C) and/or soldering tip for the hand soldering application. There are no specific hand soldering recommendation for the part, since it is likely that hand soldering temperature duration is significantly less than peak reflow classification specified in the Table 2 below. 

    Maximum number of times?

    It is hard to predict, but it depends, if you solder/desolder the part by hand. If the part is handled properly, you may perform soldering and desoldering procedures a dozen times without issues. Why are you asking? This is not a typical use. Are you doing testing experiments? Generally, the part may be fine, but the pins are getting damaged, especially it is handled by inexperienced technicians without proper desoldering tools. 

    A typical double sided board will go through the reflow oven twice. If there are soldering issues, the populated board may be reflowed once or twice more.  

    MC33078 is compatible with RoHS requirements and JEDEC standard. 

    Peak temperature recommendation for reflow can be found in the following documents. 

    https://www.ti.com/lit/an/spraby1a/spraby1a.pdf?ts=1597846673226&ref_url=https%253A%252F%252Fwww.google.com%252F

    If you have other questions, please let us know. 

    Best,

    Raymond

  • 0 in reply to Raymond Zhang1
    Prodigy 20 points

    Thank you for your reply.
    Let me ask you additional questions.

    Inquiry 1
    Lead-free solder is used for hand soldering with a soldering iron.
    The optimum temperature of this lead-free solder is 250°C, so we aim for a peak soldering temperature of 260°C or less. (Iron tip temperature 280-270℃, within 2 seconds)
    Hand soldering is done so that the heat stress is not greater than the peak reflow condition. Is the idea appropriate?

    Inquiry 2
    The symptom that the IC, which was operating normally, suddenly fails was confirmed. (Abnormal heat generation of MC33078DR)
    If cracks or peeling occur inside the IC due to the reflow process, are such symptoms expected?

    Inquiry 3
    It is suspected that the MC33078DR was exposed to high temperature and humidity (85% relative humidity or higher) during transportation and storage.
    Therefore, I will remove the residual water by baking.
    What are the recommended or reference values ​​for baking conditions (time, temperature, relative humidity, etc.)?

    * The packaging material (tape and reel) stated that the temperature was 40°C or lower.

  • 0 in reply to user1225438
    TI__Guru* 76831 points

    Hi ,

    Inquiry 1
    Lead-free solder is used for hand soldering with a soldering iron.
    The optimum temperature of this lead-free solder is 250°C, so we aim for a peak soldering temperature of 260°C or less. (Iron tip temperature 280-270℃, within 2 seconds)
    Hand soldering is done so that the heat stress is not greater than the peak reflow condition. Is the idea appropriate?

    A typical lead-free solder's melting temperature is approx. 217C or 422F. Pb-Sn based solder's melting temperature is approx. 183C or 361F. 

    It seems that you have special Pb-free solder with much higher melting point. In this case, I would recommend to experiment the hand soldering procedure on a spare board. Please select a adequate soldering tip size that will carry enough thermal energy when in contact with soldered pin. Make sure that you use adequate amount of flux to limit the surface metal oxidation, keep metal surface clean and increase the heat transfer during soldering process. 

    I would reduce the solder iron tip temperature as low as it can (while still maintaining solder flow characteristics during soldering) with above guideline. Adequate amount flux means to cover the solder pins with generous amount of flux,  which the flux should cover all over the soldering tip and pins during the hand soldering process. You can clean the excess flux when the job is completed. 

    Inquiry 2
    The symptom that the IC, which was operating normally, suddenly fails was confirmed. (Abnormal heat generation of MC33078DR)
    If cracks or peeling occur inside the IC due to the reflow process, are such symptoms expected?

    It is possible if the IC's encapsulation is absorbed with high amount of moisture. These ICs should be sealed under vacuum pack or stored in a desiccator jar or cabinet. If the ICs were stored at room temperature in air for a longer period of time, it has to be dried and baked in a temperature chamber before uses. 

    Inquiry 3
    It is suspected that the MC33078DR was exposed to high temperature and humidity (85% relative humidity or higher) during transportation and storage. Therefore, I will remove the residual water by baking.
    What are the recommended or reference values ​​for baking conditions (time, temperature, relative humidity, etc.)?

    * The packaging material (tape and reel) stated that the temperature was 40°C or lower.

    Let me get back to you about the question. When ICs are in tape and reel states, it should have an adequate amount of moisture protection during transportation (recommendation is Ta < 40C). If you are concerned about the high humidity and temperature exposures, you may bake the parts before use. I am trying to find a recommend baking procedures for the issue. 

    Do you know how long the tape and reel package exposes to high humidity and temperature environments (rough estimation will do)? 

    Best,

    Raymond

  • 0 in reply to Raymond Zhang1
    TI__Guru* 76831 points

    Hi ,

    Therefore, I will remove the residual water by baking.
    What are the recommended or reference values ​​for baking conditions (time, temperature, relative humidity, etc.)?

    TI parts should receive a dry bake step per IPC/JEDEC J-STD-033 before desoldering the component. The same care steps shall be taken if TI parts have exposed to high humidity and temperature environmental for longer period of time. 

    The application report AN-2029 is TI's recommendation in handling and process surface mount IC packages.  

    https://www.ti.com/lit/an/snoa550h/snoa550h.pdf?ts=1598118338065&ref_url=https%253A%252F%252Fwww.google.com%252F

    If  you have further questions, please let us know.

    Best,

    Raymond