Method of drilling printed circuit board

A method of drilling a hole in a printed circuit board in which stacked printed circuit boards are fixed for drilling by a pressure foot for the drilling, comprising the steps of:

• setting a drill start position at which said pressure foot is not in contact with said printed circuit boards, a pulled-out position at which the pressure of said pressure foot acts on said printed circuit boards and at which a drill bit is located just above said stacked printed circuit boards, a plurality of intermediate positions successively located at certain points in a depthwise direction of said hole, switchover positions which are each located a predetermined distance above corresponding intermediate positions, and a hole bottom position at which the drilling of said hole is completed;
• setting an entry feed rate at which said drill bit initially drills said printed circuit boards, a drilling feed rate which ensures satisfactory drilling, and a rapid feed rate which is faster than said drilling feed rate;
• repeating, after said drill has been fed from said drill start position to said pulled-out position at said rapid feed rate, then from said pulled-out position to a first intermediate position at said entry feed rate, a cycle which includes a step of feeding said drill from said first intermediate position to a switchover position via said pulled-out position at said rapid feed rate and a step of feeding said drill from said switchover position to a next intermediate position at said drilling feed rate;
• and
• returning said drill to said drill start position at said rapid feed rate after said drill has reached said hole bottom position.

A method for drilling a hole having an aspect ratio, as defined by the length of the hole to the hole diameter, higher than 8.5 in an object, comprising the steps of:

• moving a pressure foot associated with a drill from a drill-start position out of contact with the object to a pulled-out position in which the pressure foot but not the drill exerts pressure on the object;
• moving the drill into the object at an entry feed rate to initiate drilling to a first intermediate position on the object while maintaining the pressure exerted by the pressure foot;
• moving the drill to a pulled-out position at a feed rate which is higher than the entry feed rate while maintaining the pressure exerted by the pressure foot;
• and
• moving the drill to a second intermediate position on the object at a drilling feed rate lower than the rapid feed rate while maintaining the pressure exerted by the pressure foot.

A method for drilling a hole having an aspect ratio, as defined by the length of the hole to the hole diameter, higher than 8.5 in stacked circuit boards, comprising

• moving a pressure foot associated with a drill from a drill-start position out of contact with said stacked circuit boards at a rapid feed rate to a pulled-out position in which said pressure foot is in pressure contact with said stacked circuit boards and said drill is located just out of contact therewith, and
• moving said drill into said stacked circuit boards at an entry feed rate, which is lower than the rapid feed rate to initiate drilling at an intermediate portion of a first circuit board of said stacked circuit boards to be contacted by said drill while maintaining the pressure contact by the pressure foot;
• moving said drill from the intermediate portion of said first circuit board at the rapid feed rate to the pulled-out position and then to a switchover position adjacent the intermediate portion while maintaining the pressure contact by the pressure foot;
• and
• moving said drill to another intermediate position of another circuit board of said stacked circuit boards at a drilling feed rate lower than the rapid feed rate while maintaining the pressure contact by the pressure foot.

A method of drilling a hole in a printed circuit board in which stacked printed circuit boards are fixed by a pressure foot for the drilling, comprising the steps of:

• setting a drill start position at which said pressure foot is not in contact with said printed circuit boards, a pulled-out position at which the pressure of said pressure foot acts on said printed circuit boards and at which a drill bit is located just above said stacked printed circuit boards, a plurality of intermediate positions successively located at certain points in a depthwise direction of said hole, and a hole bottom position at which the drilling of said hole is completed;
• setting an entry feed rate at which said drill bit initially drills said printed circuit boards, a drilling feed rate which ensures satisfactory drilling, and a rapid feed rate which is faster than said drilling feed rate;
• repeating, after said drill has been fed from said drill start position to a first intermediate position with the pressure foot in contact with said printed circuit boards at said entry feed rate, a cycle which includes a step of feeding said drill from said first intermediate position to said pulled-out position with the pressure foot in contact with said printed circuit boards at said rapid feed rate and a step of feeding said drill from said pulled out position to a next intermediate position with the pressure foot in contact with said printed circuit boards at said drilling feed rate;
• and
• returning said drill to said drill start position at which the pressure foot is not in contact with said printed circuit boards at said rapid feed rate after said drill has reached said hole bottom position with the pressure foot in contact with said printed circuit boards.

A method of drilling a hole in a printed circuit board in which stacked printed circuit boards are fixed for drilling by a pressure foot for the drilling, comprising the steps of:

• setting a drill start position at which said pressure foot is not in contact with said printed circuit boards, a pulled-out position at which the pressure of said pressure foot acts on said printed circuit boards and at which a drill bit is located just above said stacked printed circuit boards, a plurality of intermediate positions successively located at certain points in a depthwise direction of said hole at which the pressure foot acts on said printed circuit boards, switchover positions which are each located a predetermined distance above corresponding intermediate positions and at which the pressure foot acts on said printed circuit boards, and a hole bottom position at which the drilling of said hole is completed;
• setting an entry feed rate at which said drill bit initially drills said printed circuit boards, a drilling feed rate which ensures satisfactory drilling, and a rapid feed rate which is faster than said drilling feed rate;
• repeating, after said drill has been fed from said drill start position to said pulled-out position at said rapid feed rate, then from said pulled-out position to a first intermediate position at said entry feed rate, a cycle which includes a step of feeding said drill from said first intermediate position to a switchover position with the pressure foot in contact with said printed circuit boards via said pulled-out position at said rapid feed rate and a step of feeding said drill from said switchover position to a next intermediate position with the pressure foot in contact with said printed circuit boards at said drilling feed rate;
• and
• returning said drill to said drill start position at which the pressure foot is not in contact with said printed circuit boards at said rapid feed rate after said drill has reached said hole bottom position.