Datasheet
IBM PowerPC 750GX RISC Microprocessor
DD1.X
4. Dimensions and Signal Assignments
IBM offers a ceramic ball grid array (CBGA) that supports 292 balls for the 750GX package. This is a signal
and power compatible footprint to the PowerPC 750FX RISC Microprocessor module. Use A01 corner desig-
nation for correct placement. Use the five plated dots that form a right angle (|_) to locate the A01 corner.
4.1 Package
4.1.1 Reduced-Lead package
This section describes the reduced-lead package, as indicated by the ‘R’ in the Package code field of the part
number. For the reduced lead package, lead-free solder is used for the substrate capacitors and the BGA
balls on the bottom of the package. Standard high melting point 97Pb3Sn solder (exempted by EU RoHS
legislation) is used for the C4 balls that connect the die to the substrate. The resulting module is RoHS
compatible.
All Datasheet electrical specifications apply equally to standard and reduced-lead parts.
4.1.1.1 Mechanical Specifications
The reduced-lead 292-CBGA package uses the same signal pinout, ball center-to-center spacing, and
21x21mm package outline as the leaded package. The solder balls on the bottom of the reduced-lead
package are slightly smaller, which will decrease the overall module height when assembled onto a board.
Heatsink solutions should be modified accordingly.
Table 4-1. Standard and Reduced-Lead Package, Layout, and Assembly Differences
CBGA
Card Solder
Card Solder
Screen
Diameter
Solder Ball
Composition
Solder Ball
Diameter
Card Pad
Diameter
Package
JEDEC MSL
Substrate I/O Mask Opening
Pad Diameter
31.5 (0.80)
Diameter
26.5mil open-
ing in 7.5mil
thick stencil,
2500-4600
cubic mils
Sn 10%
Pb 90%
Standard
1
31.5 (0.80)
25 (0.635)
31.5 (0.80)
27.5 (0.70)
24 (0.61)
23mil opening
in 4mil thick
stencil, 1400-
2000 cubic mils
Sn 95.5%
Ag 3.8%
Cu 0.7%
Reduced Lead
3
27.55 (0.71)
28 (0.72)
Note: All dimensions in mils unless noted. Dimensions in parenthesis are in mm.
4.1.1.2 Assembly Considerations
The reduced-lead package is compatible with a 260C lead-free card assembly reflow profile. Refer to the
NEMI Consortium, www.nemi.org, for industry-standard assembly and rework information. The coplanarity
specification for the reduced-lead CBGA, like other single melt BGA packages, is 0.20 mm (8mil).
750GX_ds_body.fm SA14-2765-02
September 2, 2005
Dimensions and Signal Assignments
Page 29 of 73
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