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Soldering a BGA chip?

Soldering a BGA chip?

2009-12-17 by mcjonster

I want to use a Xilinx Spartan 3A XC3S200AN

It comes in 256-FTBGA.

I've done .5mm pitch SMD parts with my hot air gun but never BGA.

I understand I won't be able to inspect the part but is BGA that difficult?

Can I solder it with a hot air gun?

My current technique is to put the biggest tip on my hot air gun then I just watch until all the solder has reflowed.

For the BGA, I was planning on carefully aligning it under the microscope then just hitting it with hot air from on top.  I was going to place some dabs of solder paste around the side and I figure if I heat it a minute or so after the solder dabs have reflowed then it should be ok.

I did some SMD parts with an exposed thermal pad underneath and this seemed to work fine so I guess the BGA parts will be too.

Should I invest in one of those cheap Chinese reflow ovens on ebay or is my hot air gun good enough?

Thanks.

Re: [Homebrew_PCBs] Soldering a BGA chip?

2009-12-17 by DJ Delorie

I did play with some CSP chips a while back to see if I could solder
them with my hotplate, and it worked - although you have to be careful
about lead-free solder balls on those, they melt at a higher
temperature.  IIRC I used a flux pen both on the pcb and on the solder
balls, to make sure they'd adhere properly since as you note you can't
see under them.  If you're going to use the "dab of solder" trick, use
lead-free solder.  Also, be wary of flux under the chip - water clean
is hard to get out, and no-clean conducts electricity!  It's like a
100k resistor between the balls.

The board worked, but one chip popped off when I flexed the board - I
use thinner than average boards, and it ripped the solder balls right
out of the chip!  So if you're going to do bga, use as stiff a board
as you can fab.

Re: [Homebrew_PCBs] Soldering a BGA chip?

2009-12-18 by Stefan Trethan

I've hear the chinese ovens are no good (uneven heat).
Better build a hotplate or something.

I haven't tried BGA yet, but my plan would be pretty much the same as yours.

You can inspect, at least near the edge, by fitting a 45degree mirror
to a pocket microscope or camera. I believe such a homemade inspection
camera was shown on the "fat man and circuit girl" show (google).

ST
Show quoted textHide quoted text
On Thu, Dec 17, 2009 at 7:32 PM, mcjonster <mcjonster@...> wrote:

> Should I invest in one of those cheap Chinese reflow ovens on ebay or is my hot air gun good enough?
>
> Thanks.
>

Re: Soldering a BGA chip?

2009-12-18 by blue_eagle74

I have done BGA's at work. I used a hot plate and a hot air gun. use flux and the solder on the part. Dont use any paste because it will make it ununiform, possibly lifting one side leaving unsoldered balls, unless you have a paste plate. We had a test fixture for the board to confirmed it worked.

There was a silkscreen to help me align the part, not the best idea since the silkscreen can be off. inspecting position on each corner should be good. Once done inspect the distance of each corner from the board to make sure it is uniform.

Brian

--- In Homebrew_PCBs@yahoogroups.com, "mcjonster" <mcjonster@...> wrote:
Show quoted textHide quoted text
>
> I want to use a Xilinx Spartan 3A XC3S200AN
> 
> It comes in 256-FTBGA.
> 
> I've done .5mm pitch SMD parts with my hot air gun but never BGA.
> 
> I understand I won't be able to inspect the part but is BGA that difficult?
> 
> Can I solder it with a hot air gun?
> 
> My current technique is to put the biggest tip on my hot air gun then I just watch until all the solder has reflowed.
> 
> For the BGA, I was planning on carefully aligning it under the microscope then just hitting it with hot air from on top.  I was going to place some dabs of solder paste around the side and I figure if I heat it a minute or so after the solder dabs have reflowed then it should be ok.
> 
> I did some SMD parts with an exposed thermal pad underneath and this seemed to work fine so I guess the BGA parts will be too.
> 
> Should I invest in one of those cheap Chinese reflow ovens on ebay or is my hot air gun good enough?
> 
> Thanks.
>

Re: Soldering a BGA chip?

2009-12-18 by mcjonster

I have another question for BGA layout:

Can I use a 2 sided board for a BGA and route wires between solder pads and put vias in there also or am I stuck with 4+ layer board?

Thanks.

--- In Homebrew_PCBs@yahoogroups.com, "blue_eagle74" <blue_eagle74@...> wrote:
Show quoted textHide quoted text
>
> I have done BGA's at work. I used a hot plate and a hot air gun. use flux and the solder on the part. Dont use any paste because it will make it ununiform, possibly lifting one side leaving unsoldered balls, unless you have a paste plate. We had a test fixture for the board to confirmed it worked.
> 
> There was a silkscreen to help me align the part, not the best idea since the silkscreen can be off. inspecting position on each corner should be good. Once done inspect the distance of each corner from the board to make sure it is uniform.
> 
> Brian
> 
> --- In Homebrew_PCBs@yahoogroups.com, "mcjonster" <mcjonster@> wrote:
> >
> > I want to use a Xilinx Spartan 3A XC3S200AN
> > 
> > It comes in 256-FTBGA.
> > 
> > I've done .5mm pitch SMD parts with my hot air gun but never BGA.
> > 
> > I understand I won't be able to inspect the part but is BGA that difficult?
> > 
> > Can I solder it with a hot air gun?
> > 
> > My current technique is to put the biggest tip on my hot air gun then I just watch until all the solder has reflowed.
> > 
> > For the BGA, I was planning on carefully aligning it under the microscope then just hitting it with hot air from on top.  I was going to place some dabs of solder paste around the side and I figure if I heat it a minute or so after the solder dabs have reflowed then it should be ok.
> > 
> > I did some SMD parts with an exposed thermal pad underneath and this seemed to work fine so I guess the BGA parts will be too.
> > 
> > Should I invest in one of those cheap Chinese reflow ovens on ebay or is my hot air gun good enough?
> > 
> > Thanks.
> >
>

Re: [Homebrew_PCBs] Re: Soldering a BGA chip?

2009-12-18 by DJ Delorie

"mcjonster" <mcjonster@...> writes:
> Can I use a 2 sided board for a BGA and route wires between solder
> pads and put vias in there also or am I stuck with 4+ layer board?

It depends on the chip and what you want to do with it.  For example,
I just did a layout (not etched) for a 6x8 (=48) BGA adapter that was
single sided:

  http://www.delorie.com/electronics/adapters/

In theory, you can do larger BGAs as long as you won't have signal
integrity or power spike issues - the inner planes help mitigate
those.  You can route the outer four rows of balls out with two
layers, but you still need to get your power and ground in there -
usually those are on the inner balls, and you'll need bypass caps in
there.

Note, however, that doing your own PCBs at home with BGAs will only
work if you can do plated vias - a wire sticking up under there will
cause problems.

Re: Soldering a BGA chip?

2009-12-18 by blue_eagle74

I etch my own boards. single and double. Not sure about the routing wires between pads, not much room at all or are you talking about traces (i hope)? I havent tried using bga's on my homemade boards, I would never get it to work.

The number of layers depends on how many 'pins' you plan on using. At work I deal with 1 to 14 layers. Most boards with bga's have 7 or more layers. All the boards I work with have vias for every pad to take it to the layer it needs.

Brian

--- In Homebrew_PCBs@yahoogroups.com, "mcjonster" <mcjonster@...> wrote:
Show quoted textHide quoted text
>
> I have another question for BGA layout:
> 
> Can I use a 2 sided board for a BGA and route wires between solder pads and put vias in there also or am I stuck with 4+ layer board?
> 
> Thanks.
> 
> --- In Homebrew_PCBs@yahoogroups.com, "blue_eagle74" <blue_eagle74@> wrote:
> >
> > I have done BGA's at work. I used a hot plate and a hot air gun. use flux and the solder on the part. Dont use any paste because it will make it ununiform, possibly lifting one side leaving unsoldered balls, unless you have a paste plate. We had a test fixture for the board to confirmed it worked.
> > 
> > There was a silkscreen to help me align the part, not the best idea since the silkscreen can be off. inspecting position on each corner should be good. Once done inspect the distance of each corner from the board to make sure it is uniform.
> > 
> > Brian
> > 
> > --- In Homebrew_PCBs@yahoogroups.com, "mcjonster" <mcjonster@> wrote:
> > >
> > > I want to use a Xilinx Spartan 3A XC3S200AN
> > > 
> > > It comes in 256-FTBGA.
> > > 
> > > I've done .5mm pitch SMD parts with my hot air gun but never BGA.
> > > 
> > > I understand I won't be able to inspect the part but is BGA that difficult?
> > > 
> > > Can I solder it with a hot air gun?
> > > 
> > > My current technique is to put the biggest tip on my hot air gun then I just watch until all the solder has reflowed.
> > > 
> > > For the BGA, I was planning on carefully aligning it under the microscope then just hitting it with hot air from on top.  I was going to place some dabs of solder paste around the side and I figure if I heat it a minute or so after the solder dabs have reflowed then it should be ok.
> > > 
> > > I did some SMD parts with an exposed thermal pad underneath and this seemed to work fine so I guess the BGA parts will be too.
> > > 
> > > Should I invest in one of those cheap Chinese reflow ovens on ebay or is my hot air gun good enough?
> > > 
> > > Thanks.
> > >
> >
>

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