Molded intelligent power module

This invention relates generally to a molded intelligent power module (IPM) for driving a motor. More particularly, the present invention relates to a molded IPM having a reduced top surface area and a reduced number of leads compared to a conventional IPM.

A conventional IPM uses an insulated metal substrate (IMS). The IMS is usually clamped by two copper layers. In the present disclosure, the use of lead frame and die paddles in an over-mold type IPM simplifies the manufacturing process and reduces the fabrication cost. A conventional IPM for driving a motor has three driving integrated circuits (ICs). In the present disclosure, the IPM has a low voltage IC and a high voltage IC.

Compact package size is achieved by optimization of the layout. The optimization includes use of two driving ICs instead of three driving ICS and introduction of conformal curved sides along adjacent die paddles. Reduction of the number of leads is achieved by attaching the two driving ICs on a same tie bar and wire-bonding three boost diodes to a selected lead connected to a power supply pin.

The present invention discloses an IPM having a first, second, third and fourth die paddles, a first, second, third, fourth, fifth and sixth metal-oxide-semiconductor field-effect transistors (MOSFETs), a tie bar, a low voltage IC, a high voltage IC, a first, second and third boost diodes, a plurality of leads and a molding encapsulation. The first MOSFET is attached to the first die paddle. The second MOSFET is attached to the second die paddle. The third MOSFET is attached to the third die paddle. The fourth, fifth and sixth MOSFETs are attached to the fourth die paddle. The low and high voltage ICs are attached to the tie bar. The molding encapsulation encloses the first, second, third and fourth die paddles, the first, second, third, fourth, fifth and sixth MOSFETs, the tie bar, the low and high voltage ICs, and the first, second and third boost diodes.

At least four through holes are located along a trench separating the tie bar and the first, second, third and fourth die paddles. The at least four through holes are between a middle section of a lower side edge of the tie bar and upper side edges of the first, second, third and fourth die paddles. Through holes help to reduce moisture formation. The at least four through holes are configured to receive at least four supporting pins during a molding process.

FIG. 1 is a circuit diagram of an intelligent power module (IPM) for driving a motor in examples of the present disclosure.

FIG. 2 is a perspective view of an IPM in examples of the present disclosure.

FIG. 3 is a bottom view of an IPM (with a molding encapsulation not shown) in examples of the present disclosure.

FIG. 4A is a top view, FIG. 4B is a cross-sectional view perpendicular to AA plane and FIG. 4C is a side view of an IPM in examples of the present disclosure.

FIG. 1 is a circuit diagram 100 of an IPM for driving a motor in examples of the present disclosure. A low voltage integrated circuit (IC) 120 controls a first transistor 142 , a second transistor 144 and a third transistor 146 . A high voltage IC 122 controls a fourth transistor 152 , a fifth transistor 154 and a sixth transistor 156 . In examples of the present disclosure, the transistors are metal-oxide-semiconductor field-effect transistors.

FIG. 2 is a perspective view of an IPM 200 in examples of the present disclosure. In one example, a top surface area 202 of the IPM 200 is at most 500 square millimeters. A top surface area of a conventional IPM is about 750 square millimeters.

FIG. 3 is a bottom view of an IPM 300 (with a molding encapsulation 498 of FIG. 4A not shown) in examples of the present disclosure. The IPM 300 has a first die paddle 302 A, a second die paddle 302 B, a third die paddle 302 C, a fourth die paddle 302 D, a first transistor 342 , a second transistor 344 , a third transistor 346 , a fourth transistor 352 , a fifth transistor 354 , a sixth transistor 356 , a tie bar 310 , a low voltage IC 320 , a high voltage IC 322 , a first boost diode 372 , a second boost diode 374 , a third boost diode 376 , a plurality of leads 380 and a molding encapsulation 498 of FIG. 4A .

The first die paddle 302 A, the second die paddle 302 B, the third die paddle 302 C, and the fourth die paddle 302 D are separated from each other and arranged one by one next each other in sequence with one edge of each die paddle aligned substantially in a line. The first transistor 342 is attached to the first die paddle 302 A. The second transistor 344 is attached to the second die paddle 302 B. The third transistor 346 is attached to the third die paddle 302 C. The fourth transistor 352 , the fifth transistor 354 and the sixth transistor 356 are attached to the fourth die paddle 302 D.

The tie bar 310 extends along the aligned edges of the die paddles. A first end 312 of the tie bar 310 extends beyond an outer edge of the first die paddle 302 A. A second end 314 of the tie bar 310 extends beyond an outer edge of the fourth die paddle 302 D. In examples of the present disclosure, the tie bar 310 further includes a mid-range extension 316 between the first end 312 and the second end 314 . The mid-range extension 316 of the tie bar 310 is mechanically and electrically connected to a ground pin. The mid-range extension 316 extends along a lateral direction (Y-direction) perpendicular to aligned edges of the die paddles. The low voltage IC 320 is attached to a first expansion area of the tie bar 310 between the first end 312 and the mid-range extension 316 adjacent the second die paddle 302 B. In examples of the present disclosure, the low voltage IC 320 is electrically connected to the first transistor 342 , the second transistor 344 and the third transistor 346 by bonding wires 306 . The high voltage IC 322 is attached to a second expansion area of the tie bar 310 between the second end 314 and the mid-range extension 316 adjacent the fourth die paddle 302 D. In examples of the present disclosure, the high voltage IC 322 is electrically connected to the fourth transistor 352 , the fifth transistor 354 and the sixth transistor 356 by bonding wires 308 .

In examples of the present disclosure, the molding encapsulation 498 of FIG. 4A encloses the first die paddle 302 A, the second die paddle 302 B, the third die paddle 302 C, the fourth die paddle 302 D, the first transistor 342 , the second transistor 344 , the third transistor 346 , the fourth transistor 352 , the fifth transistor 354 , the sixth transistor 356 , the tie bar 310 , the low voltage IC 320 , the high voltage IC 322 , the first boost diode 372 , the second boost diode 374 and the third boost diode 376 . In examples of the present disclosure, the plurality of leads 380 are partially embedded in the molding encapsulation 498 of FIG. 4A . In examples of the present disclosure, end surfaces of the first end 312 and the second end 314 of the tie bar 310 are exposed from edge surfaces of the molding encapsulation 498 .

In examples of the present disclosure, upper side edges 362 , 364 , 366 and 368 of the first die paddle 302 A, the second die paddle 302 B, the third die paddle 302 C and the fourth die paddle 302 D are aligned. A middle section 318 of a lower side edge of the tie bar 310 is parallel to the upper side edges 362 , 364 , 366 and 368 . At least four through holes 488 A, 488 B, 488 C and 488 D of FIG. 4A are between the middle section 318 of the lower side edge of the tie bar 310 and the upper side edges 362 , 364 , 366 and 368 of the first die paddle 302 A, the second die paddle 302 B, the third die paddle 302 C and the fourth die paddle 302 D. The at least four through holes 488 A, 488 B, 488 C and 488 D of FIG. 4A are aligned along a longitudinal direction (X-direction). The at least four through holes 488 A, 488 B, 488 C and 488 D of FIG. 4A are configured to receive at least four supporting pins during a molding process.

In examples of the present disclosure, a first bonding wire 304 A connects the first boost diode 372 to an adjacent lead 388 of the plurality of leads 380 . A second bonding wire 304 B connects the second boost diode 374 to the first boost diode 372 . A third bonding wire 304 C connects the third boost diode 376 to the second boost diode 374 . In examples of the present disclosure, the adjacent lead 388 of the plurality of leads 380 is a power supply (Vcc) pin.

In examples of the present disclosure, a first curved side 334 of the third die paddle 302 C and a second curved side 336 of the fourth die paddle 302 D have a same center of curvature 332 . A radius of curvature of the first curved side 334 is larger than a radius of curvature of the second curved side 336 .

A first connecting member 392 connects the first die paddle 302 A to a first lead 382 of the plurality of leads 380 . A second connecting member 394 connects the second die paddle 302 B to a second lead 384 of the plurality of leads 380 . A third connecting member 396 connects the third die paddle 302 C to a third lead 386 of the plurality of leads 380 . The first connecting member 392 , the second connecting member 394 and the third connecting member 396 have a same width. In examples of the present disclosure, the same width is at least 1.2 millimeters. A width of a conventional connecting member is in the range from 0.7 millimeters to 0.8 millimeters. A wider connecting member provides stronger mechanical support, increases electrical current capability by reducing resistance, and increases heat dissipation.

In examples of the present disclosure, a total number of leads of the plurality of leads 380 is at most 23. A total number of leads of a conventional IPM is at least 26.

FIG. 4A is a top view, FIG. 4B is a cross-sectional view perpendicular to AA plane and FIG. 4C is a side view of an IPM 400 in examples of the present disclosure. Through holes 488 A, 488 B, 488 C and 488 D help to reduce moisture formation.

In examples of the present disclosure, the molding encapsulation 498 has a first cutout 452 near the first end 312 of the tie bar 310 and a second cutout 454 near the second end 314 of the tie bar 310 . The first and second cutouts 452 and 454 are for screw mounts. In examples of the present disclosure, the first and second cutouts 452 and 454 are of half circular shapes.

In examples of the present disclosure, the molding encapsulation 498 has isolation cutouts 478 A, 478 B and 478 C near the first boost diode 372 , the second boost diode 374 and the third boost diode 376 .

In examples of the present disclosure, at least two selected leads 468 of the plurality of leads 380 of FIG. 3 have rectangular cutouts so as to serve as lead stoppers.

Those of ordinary skill in the art may recognize that modifications of the embodiments disclosed herein are possible. For example, a total number of the selected leads 468 having rectangular cutouts may vary. Other modifications may occur to those of ordinary skill in this art, and all such modifications are deemed to fall within the purview of the present invention, as defined by the claims.