Method for assigning pins to connection points

• US 5,360,767 A
• Filed: 04/12/1993
• Issued: 11/01/1994
• Est. Priority Date: 04/12/1993
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Lui, Lok T., Narayanan, Vinod, Honsinger, Philip, Lin, Shuhui
• Primary Examiner(s): Chaudhuri, Olik
• Assistant Examiner(s): TSAI, H JEY
• Application Number:
  US08/044,659
• Time in Patent Office: 568 Days
• Field of Search: 257/206, 257/207, 257/208-211, 257/697, 364/491, 437/208, 437/189, 437/250
• US Class Current: 716/130
• CPC Class Codes: H01L 2224/16225 the item being non-metallic, e.g. insulating substrate with or without metallisation
• CPC Class Codes: H01L 23/5386 Geometry or layout of the interconnection structure
• CPC Class Codes: H01L 2924/09701 Low temperature co-fired ceramic [LTCC]
• CPC Class Codes: H01L 2924/15192 Resurf arrangement of the internal vias

Abstract

A method of assigning pins to corresponding connection points in the design of computer modules where connection points on one layer need to be electrically connected through the pins to a wiring layer so as to minimize the length of the wiring between the points. A best area for selecting a pin is identified for each point that needs to use a pin, and pins are preferentially assigned to the points from their respective best areas. The method introduces a consideration of the direction of the destination point into the assignment solution and allows previous assignment methods to be used which incorrectly assumed that the direction to the destination point could be ignored.

Claims

1. A method for assigning pins connecting first and second layers of a multilayer electrical device to connection points located on the first layer and for connecting the connection points to assigned pins which are to be further connected through wiring located on the second layer, comprising the steps of:

a. identifying the location of a first connection point on the first layer that needs to be assigned to a pin and the location of a destination point to be connected to the first connection point through the pin;

b. computing the location of a first area located about the first connection point, the first area including all points on the first layer within a first length limit distance from the first connection point, the first length limit distance being determined by physical characteristics of the first layer that limit the length of wires formed within the first layer;

c. computing the location of a second area located about the destination point, the second area including all points on the second layer within a second length limit distance from the destination point, the second length limit distance being determined by physical characteristics of the second layer that limit the length of wires formed within the second layer;

d. computing an enclosing rectangle for the first connection point and the destination point, the first connection point and the destination point being located on opposite vertices of the enclosing rectangle;

e. determining a best area for selecting the pin to be assigned to the first connection point by calculating the overflapping intersection of the first area, the second area and the enclosing rectangle;

f. assigning a pin located within the best area to the first connection point; and

g. connecting the first connection point to the second layer through the assigned pin by forming a wire in the first layer between the first connection point and the assigned pin, the wire having a length that is no longer than the first length limit.

2. A method for assigning pins to connection points according to claim 1 wherein:

step (a) comprises identifying the location of a second connection point as the destination point when no pin has been assigned for use by the second connection point and identifying the pin assigned for use by the second connection point as the destination point when a pin has been previously assigned for use by the second connection point.

3. A method for assigning pins to connection points according to claim 1 wherein:

step (b) comprises computing a first manhattan circle as the first area, centered about the first connection point, the first manhattan circle having a manhattan length diameter determined by the first length limit and;

step (c) comprises computing a second manhattan circle as the second area, centered about the destination point, the second manhattan circle having a manhattan length diameter determined by the second length limit.

5. A method for assigning pins to connection points according to claim 1, further including the steps of:

h. computing a cost for assigning each of a plurality of pins to the first connection point;

i. assigning the lowest cost for pins that fall within the best area for pin assignment for the first connection point;

j. repeating steps (a) through (i) for each connection point that needs to be assigned a pin; and

k. performing pin assignment.

6. A method for assigning pins to connection points according to claim 5, wherein step (k) includes the step of performing pin assignment by linear assignment to minimize the total assignment cost.

7. A method for assigning pins to connection points according to claim 1, wherein step (e) includes the step of transforming coordinate systems for the first and second areas, the step of transforming coordinate systems being performed before the step of calculating the intersection of the first and second areas.

8. A method for assigning pins to connection points according to claim 7, wherein the first and second areas are initially in an x, y coordinate system and the step of transforming coordinate systems comprises transforming the x,y coordinate system of the first and second areas into an (x+y),(x-y) coordinate system before calculating the intersection of the first and second areas.

4. A method for assigning pins to connection points according to claim further comprises:

in step (a) identifying at least one additional destination point to be connected to the first connection point through the pin;

the method further includes the step of computing the location of an area about each additional destination point that includes pins closer to the additional destination point than a length limit for wires from the additional destination point to the pin;

in step (d) computing an enclosing rectangle for the first connection point and all destination points; and

in step (e) determining a best area for selecting the pin to be assigned to the first connection point by calculating the intersection of the first area, the second area, the enclosing rectangle and all areas about additional destination points.