[ARC5] Scope Question

[Bob kb8tq]

HI

BGA = ball grid array
Ball = what connects between the IC package and the PCB
Re-ball = balls fall off when you pull one off the board, you need to put new ones on

Basically it is a high density IC package. There are a lot of parts you can only get in 
BGA format these days. The process of moving over to it as a package began in bulk 
about 15 years ago. Since then the spacing of the balls on the bottom of the parts has
gotten tighter and tighter. Handling modern parts with < 0.5 mm spacing can get a bit
exciting. You get into things like laser hole drilling on the PCB to get to the contacts even
with an eight layer board. 

Since the connections are *under* the silicon chip, the lead inductance can be pretty low. 
Getting in and probing a connection with a ‘scope … not so much. The only practical way
to check the connection integrity is with an x-ray setup. Fortunately, once the assembly
process is tuned up, that really isn’t needed. 

Connection densities range from a half dozen contacts up into the many hundreds of 
connections. Things like a 144 contact arrangement in a 12 x 12 grid are not uncommon. 

Lots of fun !!!

Bob

> On Mar 21, 2018, at 12:19 PM, Kenneth G. Gordon <kgordon2006 at frontier.com> wrote:
> 
> On 21 Mar 2018 at 14:31, J Mcvey via ARC5 wrote:
> 
>> Some of the BGA components fail not because of the silicon, but because the 
>> solder connections crack. Reflowing them will sometimes restore operation, but is 
>> not always reliable. They actually need to be removed, cleaned and re-balled- but 
>> who wants to do that?
> 
> OK. Educate me here: first what is a BGA component? And secondly, what does "reballed" 
> mean?
> 
> Ken W7EKB
> 
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