104 using a lead frame construction or other similar module of multiple metal clips that can be configured as a unitary component arrangement of metal clips 402, such as metal clips 104a and 104b. Individual ones of the metal clips 402 can be connected to other individual ones of the metal clips 402, such as at predefined distances from each other. These can connected either by a single tie-bar structure as in the arrangement of metal clips 406 or a double tie-bar structure as in the arrangement of metal clips 408. For example, the lead frame can include tie-bars 404 that can be made of the same material as the metal clips 104a, 104b. The lead frame of multiple clips 402 may be fabricated as a unit. This unit may be made from the same material as the metal clips 104a, 104b. The unitary lead frame can then be positioned or assembled with respect to one or more other components. Transfer molding or other suitable fabrication processes can be used in such fabrication or assembly. Then, a material removal technique, such as wet or dry etching, can be selectively performed, such as using photolithographic or other techniques. The tie bars 404 can be selectively severed, such as to remove electrical conduction pathways along the tie-bars 404.

FIG. 5 and FIG. 6 shows a top view of the metal clips using lead frame construction using a dual bridge and single bridge design respectively. The sideview shows that the thickness of the tie-bars 404, while being the same material as the metal clips are not the same thickness of the metal clips. For example, the thickness of the tie-bars 404 can be about half of that of the metal clip 104. Then, obtaining the tie-bar 404 thickness can be done by a material removal method such as wet or dry chemical etching can be used to selectively remove the tie-bars 404 of the lead frame. This can be done such that the tie-bars are etched along the bottom side 404 of the metal. Such selective etching (i.e. half-etch process) can include using photolithographic or other techniques, such as selectively etching the tie bars 404. The resulting lead frame, which may have been initially made at the same thickness as the metal clips 104a and 104b, may be reduced in thickness by about half. The bend angle 206 of the folded-over portion of either the metal clips 104a and 104b can range from 80° to 90° for the angle between the vertical interconnect portion and the folded-over portion of the metal clips 104a, and 104b. In order to obtain this bend angle 206 the radius of the bend 210 (R) is twice the thickness 208 (T) of the material of the metal clips 104a and 104b.

Along with selectively etching the tie-bars 404, the topside of the folded-over portion of the metal clips on the unitary lead-frame 402 component, including the metal clips 104a, 104b, can also be masked off and selectively etched the edges of the metal clips creating a structural step 502. The structural step 502 allows for the mold flow material to mechanically hold the metal clips 104a and 104b in place. Such a structural step 502 at the edge of the metal clips 104a, 104b can be helpful during a subsequent fabrication process step, such as during transfer molding.

For example, an assembly method can include providing or obtaining the metal clips being connected via tie-bars 404, which can be carried as a unitary “lead frame” 402 that connects a plurality of metal clip connector pads. The unitary lead frame 402 includes component of metal clips 104a and 104b and may include at least two other metal clips can then be placed on and electrically connected to the substrate 102, such as for electrically connecting the circuit packages 106 via the metal clips and interconnections made within the substrate 102.

The unitary lead frame 402 may be fabricated as a unit, then assembled with the substrate 102 or other components. During molding, the structural step can provide a structural element that is easier for a mold flow material to be able to physically attach to the metal clips 104a, 104b. Since the lead frame is either etched or cut away by that point, the structural step the edge of the metal clips 104a, 104b helps provide further support and holds the metal clips 104a, 104b in place on the substrate 102.

The lead frame, including and carrying the metal clips 104a and 104b, can be placed on the substrate 102. The lead frame can be placed such that the folded-over portions of the metal clips 104a and 104b can be located over the surface-mounted electrical components at the connector pads. Then, the tie-bars 404 can be removed to create electrical isolation between the individual metal clips, at least at regions above the substrate 102. This can include mechanically sawing or otherwise removing portions of the tie-bars 404 of the lead frame, thereby transforming the unitary lead frame 402 component into individuated metal clips 104a, 104b.

The transfer molding process can be performed before (or after) the tie-bars 404 are cut. For example, a molding layer can be injected over the substrate 102 and the first circuit package 106 such as to help provide additional structural support. The molded layer formed by the transfer molding can leave the top side of the metal clips exposed, such as for electrical contact with the third circuit, package 108.

FIG. 7 shows an example of a stacking approach, such as for use with pre-packaged electronic components. For example, this stacking approach can help for providing a compact footprint for power converters or other componentry, such as to step-up or boost low Vin inputs or to step-down or buck high Vin inputs. This approach can be used without any changes needed for the internal components of the pre-packaged electronic circuit components. The metal clips 706, 708, and 714 can be placed as desired, such as to connect a bottom region of pre-packaged electronic circuit components to the substrate 102.

The overlaying third circuit package 108 can include a voltage regulator 704. The first metal clip 706 can be electrically connected to a voltage terminal of the first voltage regulator 704 to the first metal clip 706. The output of the output of the voltage regulator 704 is then used as an input which is provided to the second voltage regulator 710 by an electrical pathway through the second metal clip 708 can provide an electrical path for providing the input voltage to the second circuit package 710 and provide an output voltage at 716. This would bypass electrical components that are mounted on the substrate.

A third metal clip 714 can be mounted on the first surface of the substrate 102. The third metal clip 714 can be electrically connected to a ground line in the substrate 102, such as via a third electrical connector on or in substrate 102. The folded-over portion of the third metal clip 714 can be equal in height to the folded-over portions of the first and second metal clips 706 and 708. The ground terminal of high voltage regulator 704 can be electrically connected to a ground terminal of the substrate 102, such as via the folded-over portion of the third metal clip 714. At locations above the substrate 102, the folded-over portion of the third metal clip 714 is electrically isolated from the first metal clip 706 and the second metal clip 708.

For an illustrative example, an input voltage of 60 volts can be stepped down to 1 volt in a two-step configuration that can use pre-packaged components to first step down the voltage from 60 volts to an intermediate voltage of 5 volts and then to further step down the intermediate voltage of 5 volts down to a 1 volt output. In FIG. 7, the input 702 of the package can receive the 60V input voltage. Using a buck configuration, the 60 volt input voltage received at the input 702 can be electrically connected and provided to the pre-packaged components of the high voltage regulator 704 resting on the first metal clip 706. The high voltage regulator 704 can convert the 60V input voltage received at the input 702 to a 5 V output voltage at the second metal clip 708. The 5V output voltage at the second metal clip 708 can be electrically connected back down to a low voltage regulator 710 via the second metal clip 708 to provide and output voltage at 716. A common electrical ground connection 712 between the high voltage regulator 704 and the low voltage regulator 710 can be provided through an electrical connection therebetween that can be provided by the third metal clip 714. This common ground connection 712 can optionally also be electrically connected to a ground line of the substrate 102.

The circuit packages 704 and 710 can additionally or alternatively include current regulators or other first and second circuits used in a two-step power conversion or other processes, for example, using any combination of voltage or current buck, boost, or buck-boost converters for providing two-stage power conversion between first and second power terminals.

FIG. 8 shows an example stacking design for use with pre-packed electronic components with isolated grounds according to another embodiment. An electrical ground 802 for the high voltage regulator 704 and separate isolated electrical ground 714 for the low voltage regulator 710 are provided. The electrical ground 802 can make use of either a third or fourth metal clip to directly connect to the substrate ground (not shown).

FIG. 9 and FIG. 10 show examples of multiple metal clips configured with Kelvin sense capability. In a heavy load current mode regulator (buck, boost, or buck-boost), the sub-miliohm inductor current sensing techniques use the inductor DC resistance (DCR) sensing network to calculate the current limit. In applications that offer the digital current readback, Kelvin sensing technique improves the accuracy of current readback. The Kelvin sense arrangement can add one or more additional voltage sensing (“Kelvin-connected”) terminals that can be connected to a high-input impedance amplifier. The high input impedance connected to such Kelvin-connected terminals can help reduce or minimize current flow through these Kelvin sense connections. This, in turn, will provide more accurate voltage sensing since there will be less voltage drop caused by minimal current flow through the Kelvin sense connections. Three-terminal or four-terminal sensing can use one or more such Kelvin sense connections, as desired, so as to improve measurement performance accuracy.

The Kelvin sense connection can extend along a dedicated electrical conduction path from one of the metal clips 104a, 104b to a desired location on the substrate 102. As a large current flows through a folded-over region of the conductive material of the metal clips 104a and 104b, less current density (and, therefore, less voltage drop) is present along the dedicated electrical conduction path extending from (1) a location on the folded-over region that is beyond the primary current flow region to (2) the desired Kelvin sense connection point on the substrate 102. Thus, the measurement can be taken at a location on the clip where there is much less—or even no—current density to cause a voltage drop that would otherwise perturb the measurement. Also, if there is a change in electrical resistance of the portion of the metal clip carrying the large current density, the change can be detected using measurement performed at the Kelvin-sense connection.

Kelvin measurements can allow accurate voltage measurements with better immunity to voltage drops caused by parasitic wiring resistance. Having Kelvin sensing capability can help allow for better controlling of a power converter with variable load capacity. The Kelvin sense voltage or current measurements obtained using the Kelvin sense measurement leads 902 or 1002 can be presented to the user, such as in a digital readout of either a voltage or a current measurement. The measurement leads 902 and 1002 can be electrically connected to current or voltage measurement circuitry that can be included in the third circuit package 108.

FIG. 9 shows an example of custom clips with Kelvin sense to provide a substantially separate dedicated electrical measurement pathway to help improve digital readback of a voltage measurement associated with current output through a primary current flow region of the custom clip. The Kelvin sense electrical connection can be at a location of the metal clip that is beyond the primary electrical current pathway carrying the bulk of the current density. In FIG. 9, the Kelvin sense electrical connection can be brought back down to the substrate 102 while still being folded over any component on package 106a or 106b. In FIG. 10, the Kelvin sense readback electrical lead can be brought straight back down to the substrate 102 from a location beyond a region of the metal clip carrying the bulk of the current density.

In some aspects, the techniques described herein relate to an apparatus including: a substrate; a first circuit package, mounted to a first surface of the substrate; a first metal clip mounted on the first surface of the substrate and electrically connected to the first circuit package via a first electrical connector on or in the substrate and folded over the first circuit package; a second circuit package, mounted to the first surface of the substrate; a second metal clip mounted on the first surface of the substrate and electrically connected to the second circuit package via a second electrical connector on or in the substrate and folded over the second circuit package; a first end of a first dielectric support connected to the folded over portion of the first metal clip and a opposite second end of the first dielectric support connected to the folded-over portion of the second metal clip, the first dielectric support providing electrical isolation and bridging mechanical support between the first and second metal clips; and a third circuit package, mounted on and electrically connected to a folded-over portion of the first metal clip and to a folded-over portion of the second metal clip, wherein the folded-over portion of the first metal clip and the folded-over portion of the second metal clip are electrically isolated from each other above the substrate.