Replacing BGA component with an LGA using an intermediate board

[Hicham M]

Hello guys,
I have 3G module in board and I want to replace it with a newer one.
The current module has BGA footprint with 188 pads, and the newer module i'm planning to use has an LGA (144 pad) footprint.

For prototyping, I was thinking to make a small board that will contain :
-on the top, the new module (in LGA footprint)
-on the bottom the current module BGA footprint to fit the place in the main board

and this small board will replace the current module (in BGA footprint)

Please, find an illustration of the my idea



What do you think guys ? is this worth trying ?

 

[barry]

I'm not an expert at this, but you are essentially trying to create a bga device. It's simple to put the bga pads on the PCB, but how do you put the solder balls on? You'll have to send it to someone who has this capability. Further, I wonder if you can actually solder this contraption; you'll have two components on top of each other being reflowed at the same time.

Anything is worth trying, but you might just drive yourself crazy with this.

 

[FvM]

Further, I wonder if you can actually solder this contraption; you'll have two components on top of each other being reflowed at the same time.

That's generally possible and similar to the situation with double-sided SMD mount. Presuming well considered footprint design, the components will stay in place during second reflow pass, even in upside down position. Only heavy components (e.g. large ferrite cores or heatsinks) have to be glued additionally.

Attaching BGA balls to a component package or a module PCB is also straightforward with a stainless-steel stencil. Reballing of BGA packages is a standard procedure in SMD repair.

 

[marce]

You are creating an interposter, use a high temp rated FR4, solder the LGA using a higher melting point solder if possible, then solder that to the board. If not possible to use a higher melting point solder it can be done with careful processing, and would be cheaper than a new layout for testing the LGA. This is done sometimes for change of devices, prototyping and correcting mistakes:grin:

 

[ArticCynda]

It's possible, but requires a lot of care and dedication. BGA reballing kits are available online, so with the necessary patience it can work, but keep in mind that the success rate drops off sharply the more pads the BGA footprint has...

 

[Hicham M]

Thank you guys for the ideas

It's possible, but requires a lot of care and dedication. BGA reballing kits are available online, so with the necessary patience it can work, but keep in mind that the success rate drops off sharply the more pads the BGA footprint has...

My BGA component has 188 ball, and the LGA has 144 pad. is this considered a lots of pads ?

 

[Mattylad]

No.

1760 would be considered a lot of pads