Re: gEDA-user: Cheap 4 layer manufacturer?

[9000 VAX <vax9000@xxxxxxxxx>]

On 10/10/05, Charles Lepple <clepple@xxxxxxxxx> wrote:
> On 10/10/05, John Griessen <john_g@xxxxxxxxxx> wrote:
> > What is it like hand assembling a BGA package?
> > Seems like positioning would be hard to get right
> > with no repeatable robot arm to move one thing away
> > from the other and check alignment.
>
> Ideally, the surface tension of the solder helps pull the part into
> alignment with the pads, but the amount of misalignment that can be
> tolerated is a function of a lot of different variables.

From my experience, if the board is fluxed with solder, it is almost
impossible to align the chip correctly. If you want to hand-solder the
chips, the board should be not-fluxed, and should have the sticky SMD
patch in place. Well, this was the case for me and I didn't use a
liquid solder paste. Maybe it is different if you use the liquid
solder paste.

vax, 9000

>
> --
> - Charles Lepple
>