Re: Fwd: Re: gEDA-user: Plastic Ball Grid Array (PBGA) packages?

[Stephen Meier <smeier@xxxxxxxxxxxxxxxxxxx>]

Ken,

Placing a BGA device is not a hand solder job. It is done in an oven 
along with all the other devices or on a specific, fairly expensive, 
piece of equipment.

I will do my best to describe it such a tool.

The BGA device is held by a vacum gripper from the top. The gripper also 
has heating elements. At this time flux might be applied to the solder 
balls that make up the bottom of the BGA.

The PCB is held above another set of heating elements but below the bga 
device and its gripper.

An optical probe is placed between the bottom of the BGA and the top of 
the pcb. This optical device is looking both up and down and is used to 
align the BGA directly above its target landpattern on the PCB.

When alignment is achieved, the optical probe is removed.

A heating cycle is then started both from bellow the PCB and from above 
the BGA at a specified point in the heating cycle the BGA is lowered 
very gently onto the the PCB and released from the vacum gripper. The 
heating cycle eventualy is ramped down and the entire board is allowed 
to cool.

A shop that I work with typically charges $100.00 to place one BGA. The 
price drops rapiddly if placing a lot of them on multiple boards.

Steve M.

P.S. I hope you don't mind. But this is a general enough question that I 
am going to post my answer back to the GEDA mailing list.



> How do you get the chip (BGA) to soldier? 
>