USE OF ADDITIONAL BONDING FINGER ROWS TO IMPROVE WIRE BOND DENSITY

Abstract: An electronic part includes an integrated circuit that has bond pads. A wire bonded package contains the integrated circuit. The wire bonded package includes bond fingers. A second row of bond fingers is located between a first row of bond fingers and a third row of bond fingers. Each bond finger in the third row of bond fingers is electrically connected to a corresponding bond finger in the first row of bond fingers. Wire bonds connect bond pads to bond fingers from the first row of bond fingers, the second row of bond fingers and the third row of bond fingers.

Description: USE OF ADDITIONAL BONDING FINGER ROWS TO IMPROVE WIRE BOND DENSITY TECHNICAL FIELD The present invention concerns processing of integrated circuits and pertains particularly to the use of one or more additional bonding finger rows to improve wire bond density. BACKGROUND Integrated circuits are generally manufactured on a wafer surface. The wafers are then divided into individual dice. Each die is packaged. Wire bonds are typically used to electrically connect rows of bond pads on the surface of a die to power rings, ground rings and rows of bond fingers in the package. Typically, in the prior art, there is an inner row of bond pads and an outer row of bond pads. Likewise there is an inner row of bond fingers and an outer row of bond fingers. The outer row of bond pads is nearest the inner row of bond fingers. Likewise, the inner row of bond pads is farthest from the outer row of bond fingers. The rows of bond fingers and the rows of bond pads may be in line or staggered. The general rule for wiring configuration is to have high wire bond loops and low wire bond loops. The low wire bond loops connect bond pads on the outer row of bond pads to the power ring, to the ground ring and to bond fingers from the inner row of bond fingers. The high wire bond loops are used to connect the bond pads on the inner row of bond pads to bond fingers from the outer row of bond fingers. In order to prevent crossed wiring, the locations for ground wire placement is significantly limited. There are also typically areas of dead space within the bond fingers. SUMMARY OF THE INVENTION In accordance with the preferred embodiment of the present invention, an electronic part includes an integrated circuit that has bond pads. A wire bonded package contains the integrated circuit. The wire bonded package includes bond fingers. Bond fingers are arranged into a first row, a second row and a third row. The second row of bond fingers is located between the first row of bond fingers and the third row of bond fingers. Each bond finger in the third row of bond fingers is electrically connected to a corresponding bond finger in the first row of bond fingers. Wire bonds connect bond pads to bond fingers from the first row of bond fingers, the second row of bond fingers and the third row of bond fingers. In the preferred embodiment of the present invention, the wire bonded package additionally includes a ground ring and a power ring. The ground ring and the power ring are placed towards an inside of the wire bonded package with respect to the first row of bond fingers. The wire bonds also connect bond pads to the ground ring and to the power ring. Also in the preferred embodiment, the bond pads are arranged into an inner row and an outer row. In an alternative preferred embodiment of the present invention, the wire bonded package additionally includes a fourth row of bond fingers. Each bond finger in the fourth row of bond fingers is electrically connected to a corresponding bond finger in the second row of bond fingers. The third row of bond fingers is between the second row of bond fingers and the fourth row of bond fingers. The present invention gives the flexibility to use the first row of bond fingers (closest to the cavity of the wire bonded package) for connection to low loop wire bonds and the second row of bond fingers for connection to high loop wire bonds. Alternatively, the second row of bond fingers can be connected to low loop wire bonds and the third row of bond fingers can be connected to high loop wire bonds. This allows the use of space which was previously considered "dead space", thereby increasing the flexibility to place power or ground wire bonds to power or ground rings, respectively. The use of what was formerly "dead space" increases bond finger density at the cost of slightly longer wire bonds. As a result of increasing bond finger density, the size of the electronic part can be reduced because of the elimination of dead space. The described embodiments of the present invention can be used for both a staggered die pad and in-line die pad design. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows wire bonds being used to connect pads of an integrated circuit die to a ground ring, a power ring and bond fingers. Figure 2 illustrates crossing of wire bonds used to connect pads of an integrated circuit die to a ground ring, a power ring and bond fingers, when wire density is increased. Figure 3 shows wire bonds being used to connect pads of an integrated circuit die to a ground ring, a power ring, bond fingers and double-bonded bond fingers in accordance with a preferred embodiment of the present invention Figure 4 shows connect pads of an integrated circuit die ready for connection to a ground ring, a power ring, and four rows of double-bonded bond fingers in accordance with a preferred embodiment of the present invention DESCRIPTION OF THE PRIOR ART Figure 1 shows a electronic part 30 having an inner row of bonding pads 31 and an outer row of bonding pads 32. Electronic part is, for example, a semiconductor device. Inner row of bonding pads 31 includes a bonding pad 3, a bonding pad 5, a bonding pad 7, a bonding pad 9, a bonding pad 11, a bonding pad 13, a bonding pad 15, a bonding pad 17 and a bonding pad 19. Outer row of bonding pads 32 includes a bonding pad 1, a bonding pad 2, a bonding pad 4, a bonding pad 6, a bonding pad 8, a bonding pad 10, a bonding pad 12, a bonding pad 14, a bonding pad 16 and a bonding pad 18. Wire bonds connect the bonding pads to a ground ring 33, a power ring 34 or a bond finger within a package. The bond fingers are either in a first (inner) row of bond fingers 35 or a second (outer) row of bond fingers 36. First row of bond fingers 35 includes a bond finger 41, a bond finger 42, a bond finger 43, a bond finger 44, a bond finger 45, a bond finger 46, a bond finger 47, a bond finger 48 and a bond finger 49. Second row of bond fingers 36 includes a bond finger 51, a bond finger 52, a bond finger 53, a bond finger 54, a bond finger 55, a bond finger 56, a bond finger 57, a bond finger 58 and a bond finger 59. The general rule for prior art wiring configurations is to have high wire bond loops and low wire bond loops. As shown in Figure 1, the low wire bond loops connect bond pads on the outer row of pads 32 to power ring 34, to ground ring 33 and to bond fingers from the first row of bond fingers 35. The high wire bond loops are used to connect the bond pads on inner row of pads 31 to bond fingers from the second row of bond fingers 36. As shown in Figure 1, low wire bond loops include the wire bond from bond pad 1 to ground ring 33, the wire bond from bond pad 2 to bond finger 41, the wire bond from bond pad 4 to power ring 34, the wire bond from bond pad 6 to bond finger 43, the wire bond from bond pad 8 to bond finger 44, the wire bond from bond pad 10 to ground ring 33, the wire bond from bond pad 12 to bond finger 46, the wire bond from bond pad 14 to bond finger 47, the wire bond from bond pad 16 to power ring 34 and the wire bond from bond pad 18 to bond finger 49. High wire bond loops include the wire bond from bond pad 3 to bond finger 51, the wire bond from bond pad 5 to bond finger 52, the wire bond from bond pad 7 to bond finger 53, the wire bond from bond pad 9 to bond finger 54, the wire bond from bond pad 11 to bond finger 55, the wire bond from bond pad 13 to bond finger 56, the wire bond from bond pad 15 to bond finger 57, the wire bond from bond pad 17 to bond finger 58 and the wire bond from bond pad 19 to bond finger 59. Bond fingers 42, 45 and 48 are in unavailable space (dead space) which is an optimal area for ground wire bonds. In the arrangement shown in Figure 1, bond pads 1, 4, 10 and 16 are connected to either ground ring 33 or power plane 34. Any changes made to connections to either ground ring 33 or power plane 34 are limited because it would result in wire crossing, which is undesirable. For example, Figure 2 shows what happens when bonding density is increased, for example, by adding a bond pad 20, a bond pad 21 and a bond pad 22 to and an attempt is made to wire bond as many bond pads and die pads as possible. In Figure 2, low wire bond loops include the wire bond from bond pad 1 to ground ring 33, the wire bond from bond pad 2 to bond finger 41, the wire bond from bond pad 4 to power ring 34, the wire bond from bond pad 6 to bond finger 42, the wire bond from bond pad 8 to bond finger 44, the wire bond from bond pad 10 to ground ring 33, the wire bond from bond pad 12 to bond finger 44, the wire bond from bond pad 14 to bond finger 45, the wire bond from bond pad 16 to power ring 34, the wire bond from bond pad 18 to bond finger 46, the wire bond from bond pad 20 to bond finger 47, the wire bond from bond pad 22 to bond finger 48. High wire bond loops include the wire bond from bond pad 3 to bond finger 51, the wire bond from bond pad 5 to bond finger 52, the wire bond from bond pad 7 to bond finger 53, the wire bond from bond pad 9 to bond finger 54, the wire bond from bond pad 11 to bond finger 55, the wire bond from bond pad 13 to bond finger 56, the wire bond from bond pad 15 to bond finger 57, the wire bond from bond pad 17 to bond finger 58 and the wire bond from bond pad 19 to bond finger 59. Bond finger 49 and wire bond 21 are unconnected. Additionally, as shown in Figure 2, the low loop wire from bond pad 6 to bond finger 42 crosses under the high loop wire from bond pad 5 to bond finger 52. Also, the low loop wire from bond pad 8 to bond finger 43 crosses under the high loop wire from bond pad 7 to bond finger 53. Additionally, the low loop wire from bond pad 12 to bond finger 44 crosses under the high loop wire from bond pad 11 to bond finger 55. The low loop wire from bond pad 14 to bond finger 45 crosses under the high loop wire from bond pad 13 to bond finger 56. The low loop wire from bond pad 16 to power ring 34 crosses under the high loop wire from bond pad 15 to bond finger 57. The low loop wire from bond pad 18 to bond finger 46 crosses under the high loop wire from bond pad 15 to bond finger 57 and the high loop wire from bond pad 17 to bond finger 58. The low loop wire from bond pad 20 to bond finger 47 crosses under the high loop wire from bond pad 15 to bond finger 57, the high loop wire from bond pad 17 to bond finger 58 and the high loop wire from bond pad 19 to bond finger 59. The low loop wire from bond pad 22 to bond finger 48 crosses under the high loop wire from bond pad 17 to bond finger 58 and the high loop wire from bond pad 19 to bond finger 59. DISCLOSURE OF THE INVENTION In a preferred embodiments of the present invention a third row of bond fingers is added to a staggered two row bond finger design such that each bond finger in the added third row is connected by a trace to a bond finger in the first bond finger row. This is illustrated in Figure 3. In Figure 3, electronic part 30 has inner row of bonding pads 31 and outer row of bonding pads 32. Inner row of bonding pads 31 includes bonding pad 3, bonding pad 5, bonding pad 7, bonding pad 9, bonding pad 11, bonding pad 13, bonding pad 15, bonding pad 17 and bonding pad 19. Outer row of bonding pads 32 includes bonding pad 1, bonding pad 2, bonding pad 4, bonding pad 6, bonding pad 8, bonding pad 10, bonding pad 12, bonding pad 14, bonding pad 16 and bonding pad 18. Since the present invention allows for increased wire bond density, additional bonding pads may be added verses prior art implementations. This is illustrated in Figure 3 by the addition of a bonding pad 20, a bonding pad 21 and a bonding pad 22, as shown. Wire bonds connect the bonding pads to ground ring 33, power ring 34 or a bond finger within package. The bond fingers are either in first row of bond fingers 35, second row of bond fingers 36, or a third row of bond fingers 37. Third row of bond fingers 37 is added in order to provide an opportunity to decrease wire bond density. First row of bond fingers 35 includes bond finger 41, bond finger 42, bond finger 43, bond finger 44, bond finger 45, bond finger 46, bond finger 47, bond finger 48 and bond finger 49. Second row of bond fingers 36 includes bond finger 51, bond finger 52, bond finger 53, bond finger 54, bond finger 55, bond finger 56, bond finger 57, bond finger 58 and bond finger 59. Third row of bond fingers 37 includes a bond finger 61, a bond finger 62, a bond finger 63, a bond finger 64, a bond finger 65, a bond finger 66, a bond finger 67, a bond finger 68 and a bond finger 69. Bond finger 41 is electrically connected by a trace to bond finger 61. Bond finger 42 is electrically connected by a trace to bond finger 62. Bond finger 43 is electrically connected by a trace to bond finger 63. Bond finger 44 is electrically connected by a trace to bond finger 64. Bond finger 45 is electrically connected by a trace to bond finger 65. Bond finger 46 is electrically connected by a trace to bond finger 66. Bond finger 47 is electrically connected by a trace to bond finger 67. Bond finger 48 is electrically connected by a trace to bond finger 68. Bond finger 49 is electrically connected by a trace to bond finger 69. The traces between bond fingers in first row of bond finger 35 and third row of bond fingers 37 provides for an option to bond to a bond finger in first row of bond finger 35 or its connected bond finger counterpart in third row of bond fingers 37. If desired, it is possible to bond to bond fingers in both rows in order to improve electrical performance. Using the arrangement shown in Figure 3 the problem of crossing wires is alleviated when bonding density is increased by adding bond pads 20, 21 and 22 to and an attempt is made to wire bond as many bond pads and die pads as possible. In Figure 3, a wire bond connects bond pad 1 to ground ring 33. A wire bond connects bond pad 2 to power ring 41. A wire bond connects bond pad 3 to bond finger 51. A wire bond connects bond pad 4 to power ring 34. A wire bond connects bond pad 5 to bond finger 62. A wire bond connects bond pad 6 to bond finger 52. A wire bond connects bond pad 7 to bond finger 63. A wire bond connects bond pad 8 to bond finger 53. A wire bond connects bond pad 9 to bond finger 64. A wire bond connects bond pad 10 to ground ring 33. A wire bond connects bond pad 11 to bond finger 54. A wire bond connects bond pad 12 to bond finger 45. A wire bond connects bond pad 13 to bond finger 55. A wire bond connects bond pad 14 to bond finger 46. A wire bond connects bond pad 15 to bond finger 56. A wire bond connects bond pad 16 to power ring 34. A wire bond connects bond pad 17 to bond finger 67. A wire bond connects bond pad 18 to bond finger 57. A wire bond connects bond pad 19 to bond finger 68. A wire bond connects bond pad 20 to bond finger 58. A wire bond connects bond pad 21 to bond finger 69. A wire bond connects bond pad 22 to bond finger 59. The above described design gives the flexibility to connect row of bond fingers 35 using low loop wire bonds and to connect row of bond fingers 36 using high loop wire bonds. Alternatively, row of bond fingers 36 can be connected using the low loop wire bonds and the row of bond fingers 37 can be connected using the high loop wire bonds. In the design shown in Figure 3, space which was previously considered "dead space" ( from bond pads 42, 45 and 48) is used, thereby increasing the flexibility to place power or ground wire bonds to power or ground rings. The use of this "dead space" increases bond finger density at the cost of slightly longer wire bonds. As a result of increasing utilized bond finger density the size of the electronic part device can be reduced by eliminating "dead space" on the device. Figure 4 shows another embodiment of the present invention in which a fourth row of bond fingers 38 is added in order to provide additional flexibility. Fourth row of bond fingers 38 includes a bond finger 71, a bond finger 72, a bond finger 73, a bond finger 74, a bond finger 75, a bond finger 76, a bond finger 77, a bond finger 78 and a bond finger 79. Bond finger 51 is electrically connected by a trace to bond finger 71. Bond finger 52 is electrically connected by a trace to bond finger 72. Bond finger 53 is electrically connected by a trace to bond finger 73. Bond finger 54 is electrically connected by a trace to bond finger 74. Bond finger 55 is electrically connected by a trace to bond finger 75. Bond finger 56 is electrically connected by a trace to bond finger 76. Bond finger 57 is electrically connected by a trace to bond finger 77. Bond finger 58 is electrically connected by a trace to bond finger 78. Bond finger 59 is electrically connected by a trace to bond finger 79. The traces between bond fingers in second row of bond finger 36 and fourth row of bond fingers 38 provides for an option to bond to a bond finger in second row of bond finger 36 or its connected bond finger counterpart in fourth row of bond fingers 38. If desired, it is possible to bond to bond fingers in both the second and fourth rows in order to improve electrical performance. The foregoing discussion discloses and describes merely exemplary methods and embodiments of the present invention. As will be understood by those familiar with the art, the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. Accordingly, the disclosure of the present invention is intended to be illustrative, but not limiting, of the scope of the invention, which is set forth in the following claims.

Claims: CLAIMS We Claim: 1. A wire bonded package for containing an integrated circuit, the wire bonded package comprising: a first row of bond fingers; a second row of bond fingers; and, a third row of bond fingers, each bond finger in the third row of bond fingers being electrically connected to a corresponding bond finger in the first row of bond fingers; wherein, the second row of bond fingers is between the first row of bond fingers and the third row of bond fingers. 2. A wire bonded package as in claim 1 additionally comprising: a ground ring; and, a power ring; wherein the ground ring and the power ring are placed towards an inside of the wire bonded package with respect to the first row of bond fingers. 3. A wire bonded package as in claim 1 additionally comprising: a fourth row of bond fingers, each bond finger in the fourth row of bond fingers being electrically connected to a corresponding bond finger in the second row of bond fingers; wherein, the third row of bond fingers is between the second row of bond fingers and the fourth row of bond fingers. 4. An electronic part comprising: a integrated circuit, the integrated circuit including bond pads; a wire bonded package for containing the integrated circuit, the wire bonded package including: a first row of bond fingers, a second row of bond fingers, and a third row of bond fingers, each bond finger in the third row of bond fingers being electrically connected to a corresponding bond finger in the first row of bond fingers, wherein, the second row of bond fingers is between the first row of bond fingers and the third row of bond fingers; and wire bonds connecting bond pads to bond fingers from the first row of bond fingers, the second row of bond fingers and the third row of bond fingers. 5. An electronic part as in claim 4 wherein the wire bonded package additionally includes: a ground ring; and, a power ring; wherein the ground ring and the power ring are placed towards an inside of the wire bonded package with respect to the first row of bond fingers; and, wherein the wire bonds also connect bond pads to the ground ring and to the power ring. 6. An electronic part as in claim 4 wherein the wire bonded package additionally includes: a fourth row of bond fingers, each bond finger in the fourth row of bond fingers being electrically connected to a corresponding bond finger in the second row of bond fingers; wherein, the third row of bond fingers is between the second row of bond fingers and the fourth row of bond fingers. 7. An electronic part as in claim 4 wherein the bond pads are arranged into an inner row and an outer row. 8. A method for connected a wire bonded package to an integrated circuit contained by the wire bonded package, the method comprising the following steps: (a) providing the integrated circuit with bond pads, and (b) providing the wire bonded package with a first row of bond fingers, a second row of bond fingers and a third row of bond fingers, the second row of bond fingers being between the first row of bond fingers and the third row of bond fingers (c) electrically connecting, each bond finger in the third row of bond fingers to a corresponding bond finger in the first row of bond fingers; and, (d) electrically connecting, with wire bonds, bond pads to bond fingers from the first row of bond fingers, the second row of bond fingers and the third row of bond fingers. 9. A method as in claim 8 additionally comprising the following steps: (e) providing the wire bonded package with a ground ring and a power ring; (f) electrically connecting, with wire bonds, bond pads to the ground ring and to the power ring. 10. A method as in claim 8 additionally comprising the following steps: (e) providing the wire bonded package with a fourth row of bond fingers, the third row of bond fingers being between the second row of bond fingers and the fourth row of bond fingers (f) electrically connecting, each bond finger in the fourth row of bond fingers to a corresponding bond finger in the second row of bond fingers; and, (g) electrically connecting, with wire bonds, bond pads to bond fingers in the fourth row of bond fingers. 11. A method as in claim 10 wherein step (b) includes arranging the bond pads into an inner row and an outer row.

Inventors: HAMZEHDOOST AHMAD, LAU DANIEL KWOK, MARTIN ROBERT J III, HAMZEHDOOST, AHMAD, LAU, DANIEL, KWOK, MARTIN, ROBERT, J., III
Applicants: KONINKL PHILIPS ELECTRONICS NV, PHILIPS SEMICONDUCTORS INC, KONINKLIJKE PHILIPS ELECTRONICS N.V., PHILIPS SEMICONDUCTORS, INC.
Application year: 2000
Main classification: H01L23
IPC codes: H01L21, H01L23