reflowing a CPU- whats the best nozzle size?

Posted on 2011-04-20
Last Modified: 2013-11-08
Hi I am going to purchase a nozzle for my hot air reflow machine but I dont know what the best type to buy is. Does anyone have any sugestions if its best to buy one that fits directly over the CPU (the nozzle is the same size as the CPU) fo for example a 35x35mm nozzle, or if it is more efficient to use a smaller nozzle such as a 10x10mm nozzle and just keep working in circles?

I can see pros and cons to both types, as I would imagine with the larger nozzle I would guess there could be a hot spot or cold spot if heat does not come out uniformly (ex one area may be 200C and another area only 175C).

With the smaller one if you ran the hot air in circlrs all over the chip, you would not have any hot spots or cold spots (unless you did not do it long enough, or if you did it too long...then you would have issues) but with the smaller nozzle it would also be more of an "uneven" reflow. Not sure if that would have any effect on the cpu or not.

Any advice?
Question by:hydrive1902
    LVL 69

    Expert Comment

    What are you trying to accomplish by doing this?  I have never heard of anyone doing this to a cpu to gain a benefit, and you could potentially damage it if the solder disconnects from a joint or flows where it isn't supposed to.
    LVL 1

    Author Comment

    I was doing it to a laptop motherboard to fix a problem caused by an overheating CPU (because the vents were clogged with dust). This problem is especially common with HP laptops (especially in the DV series HP laptops). Problems range from no LCD to no wifi connection (there are a few other problems that can occur from that as well, but them two I mentioned are the most common problems).
    LVL 69

    Accepted Solution

    I would be inclined to use a nozzle that is the same size as the cpu - it is hard to be even if you are doing it manually.
    LVL 1

    Author Comment

    Thanks, and sorry for taking so long to give points
    LVL 67

    Expert Comment

    This question has been classified as abandoned and is closed as part of the Cleanup Program. See the recommendation for more details.

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