SESION 2
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from the previous post,
when we faced some phone that use eMMC package FBGA 153 / 169, we need to make sure that spot only for eMMC or need RAM also, how to do this ?
There are two simple methode :
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1. visual check
we can read label name on the package of IC, and googling it, search as many as possible information, that make you sure this one is eMMC only or this one also have RAM inside it, that we called eMCP.
offcourse if it from samsung IC's, its easy :
- if it KL it was eMMC only
- if it KM it was eMMC + RAM ( known as eMCP )
2. pin resistance check
after ic removal, we will found BGA pads on the PCB, you already know which one is eMMC PIN and which one is RAM PIN based on PIN MAP that i posted before
now all you need to do is check some of RAM PIN on the PCB, if you didnt get the resistance value of it, so that pin might be NC / DNU, so this phone PCB only need eMMC, this is why RAM PIN is not used in this PCB ( this is not weird things, some phone use another IC as RAM, standalone RAM, POP RAM above the CPU, etc )
we can do measurement check to the bga pin in the PCB, just do simple resistance check use ohm meter, just put your red probe to the RAM PIN pad you wanna measure and put the black probe to any system ground of PCB.
from the picture bellow you can vissualy found that some of RAM PIN PAD have a surface layer circuit in the PCB, actualy we dont need to measure when we can see RAM PIN have a circuit on the surface like this, we can assume that RAM PIN is USE by PHONE PCB, and select eMCP for replacement.
if you are not sure enaugh, just remember you always always always can do the resistance check on thoose PIN.
IS NOT WEIRD THINGS !!
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Some of phone use eMMC and some of phone use eMCP, its ordinary things,
if that phone need to use eMMC only, the manufacture will put FBGA 153 / 169 eMMC, because there is no another package avaliable for eMMC only ( all of 162/186, 221, 529, 254 must be eMCP )
if some phone designed want to use eMMC + RAM LPDDR 1, package 153 / 169 is avaliable
if some phone designed want to use eMMC + RAM LPDDR 2, their PCB designer have a choose to select any eMCP in 162 / 186 package, because this kind of package is avaliable for LPDDR 2 eMCP technology.
if some phone designed want to use eMMC + RAM LPDDR3, their PCB designer can choose eMCP in 221 package, because this package known as eMCP that their RAM use LPDDR 3 technology
if some phone designed want to use eMMC + RAM LPDDR4, their PCB designer need to choose eMCP in 254 package.
as mobile phone engineers, offcourse we will found some phone use 153/169, another one use 162 / 186. another one use 221 or 529, and another one use 254, you no need to said WOW from now on
NOTE :
the eMMC blocks and RAM blocks is totaly sparate, and have their own connection, have thair own supplies, etc... and not related each other.
thankyou for visiting
see you in the next sesion,
br,
Yongky