Adding a solder mask does a lot more that just "looknice." It does what it's name implies, it masks the solder,keeping it from getting on anything but the exposed pads. With asolder mask you can create a really densely paked board with many tracesrunning next to a pad or under a SMT component and not worry aboutshorting to the traces when soldering the board. It is also almostmandatory when doing a fin pitch no lead part. Whithout the soldermask, it is almost impossible to get the solder paste to reflowproperly and not cause shorts to nearby pins. I have found thatsoldering to a board is far easier with a solder mask, especially whenusing SMT.