Basically, a via hole only makes connections from one layer of a board to another. A Component hole can do the same thing, but it's primary function is to connect the component to the circuitry. Via holes are generally smaller in size than component holes. Normal for everybody can be different but you usually see them in sizes like .012, .018, .025, .032. They can be completely exposed, totally covered (with soldermask), partially covered, blind or buried. Blind vias are vias that start on one side of the board, but stop part way through a multilayer board. It would allow you to have traces running through a location where a through via would be. A buried via is completely enclosed within the board and allows you to run track, or mount surface mount components, to the external layer over the via itself. Hope this helps somewhat. Larry Campbell Supervisor, PWB BFGoodrich, Avionics Systems What is the difference between a via hole and a component hole? How do you distinguish these two types of holes in a PCB? thanks in advance for any information. regina ################################################################ DesignerCouncil E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE DesignerCouncil <your full name> To unsubscribe: SIGNOFF DesignerCouncil ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For technical support contact Hugo Scaramuzza at [log in to unmask] or 847-509-9700 ext.312 ################################################################