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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). |
