CCGA (also called CGA) Column Grid Array IC packages are made with non-collapsible solder columns for surface mount soldering on printed circuit boards (PCB). Most CCGA packages have large ceramic substrates 21mm to 52.5mm. It is noteworthy to mention that there is increasing interest in replacing solder balls on (organic) Plastic Ball Grid Arrays (PBGA) with solder columns. CCGA packages are typically 1.0mm or 1.27mm pitch. Experimentation suggests the feasibility to use solder columns for narrower pitch CCGA packages down to 0.8mm and eventually smaller pitches.

Solder columns absorb CTE mismatch between the IC package and the PCB circuit board. CTE mismatch is inherent due to joining different material properties between the IC package and the PCB circuit board. The CTE mismatch differential between a ceramic IC package and PCB circuit board is 10ppm/°C in the X/Y axis. CTE mismatch rises above 50ppm/°C in the Z-axis as temperatures exceed the Tg rating of the PCB circuit board. As the IC package increases in size, the differentials of CTE mismatch become more significant, especially when the package is subjected to repeatedly wide temperature cycles from -40°C to +125°C.

Stress due to CTE mismatch results in eventual delamination and catastrophic electrical failure between a large ceramic BGA IC package and the PCB circuit board. The corner pads are most prone to fail as well as the corners directly under the silicon die mounted on (or in) the package.

History: In the early 1970s IBM invented CGA packages using plain Pb90/Sn10 solder columns, almost 10 years before Bell Laboratories introduced the solder ball for ceramic CBGA packages (Circa 1979-1980). In the early 1980s, Raychem improved solder columns by wrapping copper ribbon around Pb80/Sn20 solder core, with measurable improvements in operating life. In 1989 Motorola and Citizen jointly delveloped plastic BGA (PBGA) packages, originally named OMPAC (Over Molded Pad Array Carrier)

Older style solder columns are constructed of high melting temperature Pb90/Sn10 wire (or cast) without copper wrapping. Such "plain" columns tend to decrease electrical performance, especially at higher frequencies. Columns increase the overall package profile height, as compared to BGA components.

Solder columns are available in a variety of lengths from 1.0mm to 2.54mm. However, solder columns of 2.21mm nominal length tend to be the industry norm for most CCGA packages. Longer columns, such as 3.81mm, are useful for raising IC packages with bottom mounted decoupling capacitors off the circuit board.

Ideally, the diameter of the solder column should be roughly 75% of the landing pad diameter to allow a proper annular solder fillet to form around both ends of solder columns after joining the IC package to thePCB circuit board. Solder columns are available with diameters as small as Ø0.20mm and as large as Ø0.56mm (Ø0.89mm for certain applications).

Solder columns have been successfully attached to organic PBGA substrates as illustrated in Figure 2. Ø0.50mm diameter solder columns tend to be the industry norm for 1.0mm and 1.27mm pitch ceramic IC packages. Smaller size solder columns with Ø0.38mm diameter are required for commercial off-the-shelf (COTS) 1.0mm pitch organic substrates (PBGA without solder balls), since most 1.0mm pitch PBGA packages have Ø0.50mm solder mask defined pads (SMD). Even smaller solder columns Ø0.25mm ~ 0.30mm diameter are required for 0.8mm pitch PBGA packages, depending on the diameter of the solder mask defined pads.