Computer Memory Module Components

The following are some of the components in a computer memory. PCB (Printed Circuit Board) The green board that holds the memory chips is made up of several layers. Each layer contains traces and circuitry to control the movement of data. Usually, higher quality memory modules use more layers. The more layers, the more space there is between traces. With more space between traces, the module has less chance of noise interference and is more reliable.

Traces (Internal Trace Layer) Think of traces as roads that data travels on. The width and curvature as well as the distance between affect both the speed and reliability. Contact Fingers The contact fingers (connections or leads) are used to plug the memory chips into the module. Contacts can either be tin or gold. Gold is a better conductor than tin, but more expensive. To help avoid corrosion, It's always best to match the metal of the module to the metal of the socket. Chip Packaging This is the material coating around the actual silicon. Today's most common packaging are. . . DIP (Dual In-Line Package) This type of packaging was used when memory was installed directly on the computer's system board. It installed into holes extending into the surface of the PCB and could either be soldered or inserted into sockets. SOJ (Small Outline J-Lead) This type of packaging was used for surface mount components where they mounted directly onto the surface of the PCB. TSOP (Thin Small Outline Package) This is also a surface mount design and was first used to make thin credit card modules for notebook computers. CSP (Chip Scale Package) CSP doesn't use pins to connect to the board. It uses electrical connections to the board on the underside of the package. RDRAM chips utilize this type of packaging. Chip Stacking For higher capacity modules, it is necessary to stack chips on top of one another. Stacking can be internally (not visible) or externally (visible).