Integrated circuit package with lead fingers extending into a slot of a die paddle
View Patent ↗The specification describes a leadframe that is aimed at high-performance digital IC devices with high-pin counts, and packaged using wire bond technology. According to the invention the configuration of the paddle is modified to add a new dimension to the leadframe design. In a preferred embodiment, one or more slots are formed in the paddle to allow the length of selected wire bonds to be reduced. This reduces the susceptibility of these selected leads to parasitic capacitances. The selected leads are typically those that carry very high-speed signals.
1. A integrated circuit package comprising:
a leadframe having a paddle, the paddle having at least one edge with a slot formed therein;
an integrated circuit chip secured to the paddle; and
a plurality of lead fingers having a distal end adjacent to the paddle along the at least one edge, the distal end of a subset of the lead fingers extending into the slot, whereby a wire bond extending from a bond pad on the chip to the distal end of a lead finger extending into the slot is shorter than a wire bond extending from a bond pad on the chip to the distal end of a lead finger that does not extend into the slot.
2. An integrated circuit package comprising:
a. a leadframe having a paddle, the paddle having a quadrilateral shape, with length L, width W, and having four edges,
b. a plurality P+P′ of lead fingers extending from the paddle along at least two edges, where P′ is less than P,
c. an IC chip attached to the paddle, the IC chip having a quadrilateral shape with length L′, width W′, and having four edges, wherein L′ is less than L and W′ is less than W, and wherein the IC chip substantially covers the paddle except for at least one exposed region along the edge of the paddle,
the invention characterized by at least one slot formed in said exposed region, and wherein the plurality P′ of lead fingers extend into the slot.
3. The device of claim 2 further comprising wire bonds of length X attached to the plurality P of lead fingers, and wire bonds of length X′ attached to the plurality P′ of lead fingers, and wherein X′ is substantially less than X.
4. The device of claim 3 wherein X′ is less than 50% of X.
5. The device of claim 3 wherein the IC chip is a digital IC chip, and the plurality of leads P′ are selected high speed digital I/O leads.
6. The device of claim 3 wherein the slot has a length of less than 0.25L.
7. The device of claim 6 wherein the slot has a width of at least 0.50 (W–W′).
8. The device of claim 3 wherein L and W are substantially equal.
9. The device of claim 3 wherein the lead fingers P have pitch p and the lead fingers P′ have pitch p′, where p′ is larger than p.
10. The device of claim 3 wherein at least some of the lead fingers P are bent.
11. The device of claim 3 wherein at least some of the lead fingers 3 are tapered.
12. The device of claim 3 wherein the slot has tapered sidewalls.
13. A leadframe on which to secure an integrated circuit chip, to wire bond from bond pads on the integrated circuit chip to lead frame fingers, and overmold to form an integrated circuit, the leadframe comprising:
a leadframe having a paddle on which the integrated circuit chip is adapted to be secured, the paddle having at least one edge with a slot formed therein; and
a plurality of lead fingers, each lead finger having a distal end adjacent to the paddle along the at least one edge, the distal end of a subset of the lead fingers extending into the slot, whereby when a wire bond is completed from a bond pad on the chip to the distal end of a lead finger extending into the slot such wire bond will be shorter than a wire bond completed from a bond pad on the chip to the distal end of a lead finger that does not extend into the slot.
14. A integrated circuit package leadframe comprising:
a. a leadframe having a paddle, the paddle having a quadrilateral shape, with length L, width W, and having four edges,
b. a plurality P+P′ of lead fingers extending from the paddle along at least two edges, where P′ is less than P,
the invention characterized by at least one slot formed in one edge of the leadframe, and wherein the plurality P′ of lead fingers extend into the slot.
15. The leadframe of claim 14 wherein the slot has a length of less than 0.25L.
16. The leadframe of claim 14 wherein L and W are substantially equal.
17. The leadframe of claim 14 wherein the lead fingers P have pitch p and the lead fingers P′ have pitch p′, where p′ is larger than p.
18. The leadframe of claim 14 wherein at least some of the lead fingers are tapered.