Homebrew PCBs

javaguy11111 wrote:
> I am attempting my first BGA component. It is a simple 8 ball 555
> timer using 0201 and 0402 components. Toner transfer will be used and
> I think will be doable with the equipment I have. I have a microscope
> and handling the 0402 and 0201 components is not a problem. I am
> having a problem trying to figure out the best way to align the 555.
> This is a homebuilt board, so I do not have an alignment mask. 
> 
> The best idea I have thought of so far is to print out pick and place
> alignment marks,put the component over this and mark the top of the
> component with a needle dipped in some white paint. Then when I place
> the component, I would align dots with the appropriatley aligned
> trace. I have not tried this yet, but it is one idea. 
> 
> I just wanted to find out if anyone else has any ideas for trying to
> align a bga component.
> 
> I am not sure if what I am trying to do will work, but if it does the
> board should be about 5mm by 5mm.
> 


I've never touched any BGA stuff, but I would guess that if you place the 
555 close to its position and heat your 5 x 5 mm PCB with a temperature 
controlled hot air gun the device might center its self due to solder 
surface tension. A tab of solder paste on each pad might be the trick here.
I would try heating the PCB while upside down so all the components are 
held by surface tension and more likely to self center. Just don't let 
solder oxidize so keep it well fluxed with a liquid flux.

Try positing this questions to some of the USENET groups such as 
sci.electronics.design, sci.electronics.manufactureing.