1. A circuit layout device of a semiconductor integrated circuit having scan chains, comprising:
a circuit layout section for performing the circuit layout of a semiconductor integrated circuit considering a weighting factor being set for a wire of the semiconductor integrated circuit, and outputting the layout data;
a wire length calculation section for calculating a wire length of a scan chain from the layout data output by the circuit layout section;
a wire weighting section for increasing the weighting factor of the scan chain wire based on the scan chain wire length calculated by the wire length calculation section; and
a scan chain wire determination section for comparing the scan chain wire length calculated by the wire length calculation section and a predefined upper limit value of scan chain wire length, wherein the wire weighting section increases the weighting factor of the scan chain wire based on the comparison result of the scan chain wire determination section.
2. The circuit layout device according to claim 1, wherein the weighting factor of the scan chain wire is set to be lower than the weighting factor of a signal wire of the semiconductor integrated circuit.
3. A circuit layout method for a semiconductor integrated circuit having scan chains, comprising:
providing a predefined upper limit value of scan chain wire length;
performing a first circuit layout of the semiconductor integrated circuit based on connection information of a user circuit;
calculating a wire length of a scan chain wire from layout data based on the first circuit layout;
comparing the calculated scan chain wire length with the predefined upper limit;
increasing a weighting factor of a scan chain wire if the calculated scan chain wire length is determined greater than the predefined upper limit during the step of comparing; and
performing another circuit layout using the increased weighting factor of the scan chain wire.
4. One or more computer readable media storing computer readable instructions that, when executed, perform a circuit layout method of claim 3 for a semiconductor integrated circuit having scan chains.
5. The circuit layout method according to claim 3, further comprising at least one cycle of following steps:
comparing the previous calculated scan chain wire length with the predefined upper limit value of the scan chain wire length;
performing another circuit layout using a further increased weighting factor of the scan chain wire if the previous calculated scan chain wire length is determined greater than the predefined upper limit during the step of comparing;
calculating a wire length of a scan chain wire from layout data based on the another circuit layout; and
ending the cycle if the latest calculated scan chain wire length is determined smaller than or equal to the upper limit during the step of comparing.
6. One or more computer readable media storing computer readable instructions that, when executed, perform a circuit layout method of claim 5 for a semiconductor integrated circuit having scan chains.
7. The circuit layout method according to claim 3, wherein the weighting factor of the scan chain wire is set to be lower than the weighting factor of a signal wire of the semiconductor integrated circuit.
8. One or more computer readable media storing computer readable instructions that, when executed, perform a circuit layout method of claim 7 for a semiconductor integrated circuit having scan chains.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. Rotary cutting tool comprising a cutting part (12) centred on an axis of rotation (10) of the tool and comprising a side surface with at least one side cutting edge (18) and an end surface with at least one end cutting edge (20), means for feeding fluid being provided for feeding a fluid onto the end surface, close to each end cutting edge (20), the means for fluid feed comprising a central lubrication channel (22) drilled along the axis of rotation (10) of the tool and at least one secondary channel (24) linking one non-through end of the central channel (22) to the end surface, close to each end cutting edge (20), characterised in that the end cutting edge (20), relative to a plane perpendicular to the axis of rotation (10) of the tool, forms an end dedendum angle comprised between about 3 and about 20.
2. Rotary cutting tool according to claim 1, in which the non-through end of the central channel (22) is located very closely to the end surface of the cutting part (12).
3. Rotary cutting tool according to any one of claims 1 and 2, in which the secondary channels (24) have cross-sections whose sum is at least equal to the cross-section of the central channel (22).
4. Rotary cutting tool according to any one of claims 1 to 3, in which the end dedendum angle is closely equal to 6.
5. Rotary cutting tool according to any one of claims 1 to 4, in which each side cutting edge (18) comprises a non-nil circular land, less than 0.1 mm.
6. Rotary cutting tool according to any one of claims 1 to 5, in which each end cutting edge (20) comprises a first end clearance of width comprised between 0.3 mm and 0.4 mm.
7. Rotary cutting tool according to claim 6, in which the width of the first clearance is closely equal to 0.3 mm.
8. Rotary cutting tool according to any one of the preceding claims, in which said tool comprises, successively, beyond the cutting part (12) and along the axis of rotation (10) of the tool, a clearance section (14) of diameter d1 and a tail section (16) of diameter dQ, connected to each other along a connection radius RR at least equal to (dQd1)2, with a minimum of 0.1 dQ.
9. Rotary cutting tool according to claim 8, in which the clearance part (14) and the cutting part (12) are connected to each other according to an angle of about 30.
10. Rotary cutting tool according to any one of the preceding claims, in which the side and end cutting edges (18) and (20) are connected together by a rounding or a chamfer of 0.1 mm oriented at 45 relative to the axis of rotation of the tool.
11. Rotary cutting tool according to any one of the preceding claims, in which each secondary channel (24) opens onto the end surface of the cutting part (12), in a secondary clearance of an end cutting edge (20), at a distance of at least 0.5 mm from a first end clearance of said end cutting edge.
12. Cutting method using a rotary cutting tool according to any one of the preceding claims, characterised in that it consists of machining a bore in a part by a rotational movement of the tool around its axis and a forward movement of the tool along said axis, while injecting a fluid constituted of nano-droplets of lubricant through the central channel and through the secondary channel.