eMMC comes in BGA packages with many pins (100-200), yet it only uses a few of them (10-30). Why doesn't it come in a package with fewer pins instead, as wouldn't this be cheaper and easier to fit/inspect?

The BGA 153 pinout (designed by committee) can be found in this blog post.

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    \$\begingroup\$ Please provide a hyper link to the device’s data sheet. \$\endgroup\$
    – Andy aka
    Jan 11, 2020 at 14:43
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    \$\begingroup\$ A bit of speculation; I have used eMMC and there are various physical package sizes (and accordingly number of balls) due to die size requirements; as the attach strength is strongly related to balls per square area for a BGA, a fairly full grid makes sense. \$\endgroup\$ Jan 11, 2020 at 15:48

2 Answers 2


Having all data pins in roughly one place (as opposed to being distributed around the chip) makes it easier to design the PCB as all traces tend to have the same length (and thus the same propagation time) naturally.

BGA packages also have very low pin inductance values, which are desirable for high frequency operation, even if the required number of pins is low.

Once you decide to go for a BGA package (because of the two factors above), you don't really have an option to only make the pads you need for the signals. Uneven pad distribution would lead to reflow defects, poor thermal conductivity and increased mechanical stress during reflow and operation.


The size of the eMMC package is limited by the size of the silicon chip inside the package. Its size can't be reduced (with current available technology).

The number of pins could be reduced, yes, but it would also make it mechanically weaker, because the package would still be fairly large. There needs to be enough pins to keep the package mechanically connected to the PCB.

  • \$\begingroup\$ The structural integrity of ICs is provided by the lead frame, not the pins. The pins are attached to the die using tiny bond wires. \$\endgroup\$ Jan 11, 2020 at 15:08
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    \$\begingroup\$ @DmitryGrigoryev - the effective board attach strength is strongly influenced by the number of balls for a BGA (or more strictly the number of balls per square area) and may be one reason the package in question uses so many. \$\endgroup\$ Jan 11, 2020 at 15:41
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    \$\begingroup\$ +1 It's for a portable handheld device (cell phone) so mechanical strength of the PCB-BGA is pretty important. \$\endgroup\$ Jan 11, 2020 at 18:51
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    \$\begingroup\$ Do you have any references that could back up this answer? \$\endgroup\$
    – Rob Gilton
    Jan 12, 2020 at 10:10
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    \$\begingroup\$ These things are going into tiny devices, so small, low-profile packages are an absolute must. No way can they use a TSSOP or SOIC or any leaded package. It is not just the XY area but the Z-height. I believe the BGA is actually a chip-scale package, just as TemeV says. For sure it is lower than any leaded package. \$\endgroup\$
    – user57037
    Jan 13, 2020 at 8:53

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