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ball grid array packaging


A ball grid array (BGA) is a type of surface-mount packaging used for integrated circuits.The BGA is descended from the pin grid array (PGA), which is a package with one face covered (or partly covered) with pins in a grid pattern. These pins are used to conduct electrical signals from the integrated circuit to the printed circuit board (PCB) it is placed on. In a BGA, the pins are replaced by balls of solder stuck to the bottom of the package. The device is placed on a PCB that carries copper pads in a pattern that matches the solder balls. The assembly is then heated, either in a reflow oven or by an infrared heater, causing the solder balls to melt. Surface tension causes the molten solder to hold the package in alignment with the circuit board, at the correct separation distance, while the solder cools and solidifies.The BGA is a solution to the problem of producing a miniature package for an integrated circuit with many hundreds of pins. Pin grid arrays and dual-in-line surface mount (SOIC) packages were being produced with more and more pins, and with decreasing spacing between the pins, but this was causing difficulties for the soldering process. As package pins got closer together, the danger of accidentally bridging adjacent pins with solder grew. BGAs do not have this problem, because the solder is sometimes factory-applied to the package in exactly the right amount.

BGA is called as “Ball Grid Array”. A Ball Grid Array (BGA) package is similar to a PGA (Pin Grid Array) package, except that the role of the pins is taken over by small balls of conductive material. The advantage is that unlike pins, the conductors are not easily bent. Unfortunately, BGA CPU’s are soldered right onto the motherboard, and users cannot replace them. This form of packaging is seen in embedded CPU’s like those from VIA.

As programmable logic devices (PLDs) increase in density and I/O pins, the demand for small packages and diverse packaging options continues to grow. Ball-grid array (BGA) packages are an ideal solution because the I/O connections are on the interior of the device, improving the ratio between pin count and board area. Typical BGA packages contain up to twice as many connections as quad flat pack (QFP) packages for the same area. Further, BGA solder balls are considerably stronger than QFP leads, resulting in robust packages that can tolerate rough handling.

In BGA packages, the I/O connections are located on the interior of the device. Leads normally placed along the periphery of the package are replaced with solder balls arranged in a matrix across the bottom of the substrate. The final device is soldered directly to the PCB using assembly processes that are virtually identical to the standard surface mount technology preferred by system designers.
Additionally, BGA packages provide the following advantages:

■ Fewer damaged leads—BGA leads consist of solid solder balls, which are less likely to suffer damage during handling.

■ More leads per unit area—Lead counts are increased by moving the solder balls closer to the edges of package and by decreasing pitch to 1.0 mm for flip-chip BGAs and 0.8 mm for micro-BGAs.

■ Less expensive surface mount equipment—BGA packages can tolerate slightly imperfect placement during mounting, requiring less expensive surface mount equipment. The placement can be imperfect because the BGA packages self-align during solder reflow.

■ Smaller footprints—BGA packages are usually 20% to 50% smaller than QFP packages, making BGA packages more attractive for applications that require high performance and a smaller footprint.

■ Integrated circuit speed advantages—BGA packages operate well into the microwave frequency spectrum and achieve high electrical performance by using ground planes, ground rings, and power rings in the package construction.

■ Improved heat dissipation—Because the die is located at the center of the BGA package and most GND and VCC pins are located at the center of the package, the GND and VCC pins are located under the die. As a result, the heat generated in the device can be transferred out through the GND and VCC pins (i.e., the GND and VCC pins act as a heat sink).

it is a method of backside emission analysis for packaged BGA chips, comprising the steps of:

providing a BGA device having a backside and a front side, said BGA device comprising a printed circuit board having a first surface and a second surface in addition to comprising a molded plastic part having a first surface and a second surface, said second surface of said printed circuit board being in contact with said first surface of said molded plastic part, said molded plastic part comprising a BGA chip having a backside and a front side in or on the surface of said front side of said BGA chip having been created semiconductor circuits, said BGA device having a grid of contact balls mounted on said first surface of said printed circuit board said second surface of said printed circuit board having points of electrical contact that are in electrical contact with points of electrical contact that have been provided in said first surface of said molded plastic part, said points of electrical contact that have been provided in said first surface of said molded plastic part being in contact with said semiconductor devices that have been provided in or on the front side of said BGA chip;

providing a BGA device carrier;

exposing the backside of said BGA chip, then; splitting said BGA device into two parts by physically removing said printed circuit board substrate from said molded plastic part; and

performing BGA chip analysis.





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