Hi Adeline,

BGA stands for Ball Grid Array.  It is a method to facilitiate chip assembly onto printed circuit boards without having to go wire bond the chip to the board directly or use a socket.

A BGA is thin core printed circuit board ( typically 4 mil thick).  One side of th BGA has gold plated "pads" arranged in a pitch that will allow gold wire bonding of the chip onto it.  Those "pads" are connected through traces and vias to the other side of the BGA terminating at a rectangular grid of pads.  Solder balls are attached to the rectangular grid pads.  The "mother" circuit board has a similar rectangular pattern.  The chip is first gold wire bonded onto the BGA substrate and packaged.  The package is then placed on the PCB and reflowed which cause the solder balls to flow and attach to the chip to the grid pattern.

Hammad



---------- Forwarded Message ----------

FROM:    Ko Adeline-FSGA2298 <[log in to unmask]>
TO:      [log in to unmask]
DATE:    Fri, 4 Jun 1999 10:58:33 +0800

RE:      Re: [TN] stencil thickness

Hi,

May I know what is BGA?

Thanks & Best Rdgs
Adeline Ko

> -----Original Message-----
> From: Feng Yi,BISC PD IE(BJ) [SMTP:[log in to unmask]]
> Sent: Friday, June 04, 1999 10:49 AM
> To:   [log in to unmask]
> Subject:      [TN] stencil thickness
>
> Hi,
>
> We will make stencil for module with BGA, Fine pitch(0.4mm) and chip,
> because we knowed the requirement of stencil thickness it is 0.12mm for
> fine pitch(0.4mm), but it is 0.2mm for BGA, so we would like to know how
> thickness is stencil when there are both BGA and fine pitch.
>

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