Question

Assume that one component with 256 I/Os is offered in three forms: QFP, full array PBGA, and fl ip chip with gold bumps. The pitch of the QFP is 0.4 mm and the lead length is 1 mm. An edge of the QFP to the center of the nearest lead is assumed to the same as the lead pitch. The pitch of the BGA is 1.27mm and an edge to the center of the nearest solder joints is 2.5 mm. The pitch of the flip chip is 0.4 mm and an edge to the center of the nearest solder joints is1mm. Assume the underll extension is 1 mm.

1. Calculate the PCB surface area requirement for each case.

Answer 1

The calculation involves determining the side length of the PCB area required for each component type—QFP, PBGA, and flip chip—based on their respective pitches and dimensions including lead lengths, solder joint distances, and underfill extensions, and then squaring this dimension to get the area.

Step-by-step explanation:

The question asks for the calculation of the PCB surface area requirements for three different types of electronic component packages: QFP (Quad Flat Package), PBGA (Plastic Ball Grid Array), and flip chip with gold bumps, each with different pitches and dimensions.

For the QFP:

The side length of the component can be estimated by multiplying the number of I/Os by the pitch and adding twice the lead length: (256 * 0.4 mm) + (2 * 1 mm).

Add the underfill extension on all sides: Total side length + (2 * 1 mm extension).

Finally, calculate the area by squaring the total side length.

For the PBGA:

First, calculate the number of solder joints along one edge by taking the square root of the total number of I/Os.

Then, calculate the side length by multiplying the number of joints by the pitch and adding twice the distance from the edge to the center of the nearest joint.

Remember to include the underfill extension for the total dimension, then square it for the area.

For the flip chip: Repeat the process using the respective dimensions and pitches for the flip chip package.