This application claims the priority benefit of Italian Application for Patent No. 102023000017700 filed on Aug. 29, 2023, the content of which is hereby incorporated by reference in its entirety to the maximum extent allowable by law.
The description relates to manufacturing semiconductor devices.
Solutions as described herein can be applied to integrated circuit (IC) power semiconductor devices such as power quad flat no-leads (QFN) packages for automotive products, for instance.
In power semiconductor devices, the current transferred from the high-power section to the output pads of the device can be significant.
Clips or ribbons are used for conducting current transfer in the place of wires.
Clips are currently stamped from flat material and are provided with centering features such as pins that facilitate centering and keeping the clips in position during processing.
In small power QFN packages and/or if several channels are desired in the final package, more pads are needed and the dimensions for the centering features on leadframe and clips may become relatively small.
Furthermore, the singulation and handling of clips may become difficult due to a tighter and elongated shape for the clips.
Another approach is based on the use of electrically conductive ribbons to provide electrical coupling between the power section of an integrated circuit (IC) semiconductor device and the outer pads.
These ribbons are bonded via ultrasonic wedge-bonding and such a bonding method may severely damage the (relatively small) outer pads and/or the die bonding pads provided on the semiconductor die.
There is a need in the art address the issues discussed in the foregoing.
One or more embodiments relate to a method.
One or more embodiments relate to a corresponding component. An electrical coupling member for use in manufacturing (power) semiconductor devices and suited to be provided by a supplier to a manufacturer of semiconductor devices can be exemplary of such a component
One or more embodiments relate to a semiconductor device comprising such a component.
In solutions as described herein, an electrical coupling member is provided to electrically couple an integrated circuit semiconductor die to one or more (power) leads.
In solutions as described herein, an electrical coupling member may be formed via premolding technology.
Solutions as described herein contemplate providing a leadframe, mounting a die thereon, applying an electrical coupling member to provide the desired electrical couplings between the die and leads in the leadframe.
One or more embodiments will now be described, by way of example only, with reference to the annexed figures, wherein:
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated.
The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.
The edges of features drawn in the figures do not necessarily indicate the termination of the extent of the feature.
In the ensuing description one or more specific details are illustrated, aimed at providing an in-depth understanding of examples of embodiments of this description. The embodiments may be obtained without one or more of the specific details, or with other methods, components, materials, etc. In other cases, known structures, materials, or operations are not illustrated or described in detail so that certain aspects of embodiments will not be obscured.
Reference to “an embodiment” or “one embodiment” in the framework of the present description is intended to indicate that a particular configuration, structure, or characteristic described in relation to the embodiment is comprised in at least one embodiment. Hence, phrases such as “in an embodiment” or “in one embodiment” that may be present in one or more points of the present description do not necessarily refer to one and the same embodiment.
Moreover, particular conformations, structures, or characteristics may be combined in any adequate way in one or more embodiments.
The headings/references used herein are provided merely for convenience and hence do not define the extent of protection or the scope of the embodiments.
For simplicity and ease of explanation, throughout this description, and unless the context indicates otherwise, like parts or elements are indicated in the various figures with like reference signs, and a corresponding description will not be repeated for each and every figure.
An array of leads 12B is arranged around the die pads 12A having the low-power 14A die and the high-power 14B die mounted thereon.
As illustrated herein by way of example, a semiconductor device such as the device 10 comprises, in addition to a substrate (leadframe) 12 having one or more semiconductor chips or dice 14A, 14B (as used herein, the terms chip/s and die/dice are regarded as synonymous) arranged thereon: electrically conductive formations (wires, ribbons, clips) 16, 28 coupling the semiconductor dice 14A, 14B to leads (outer pads) 12B in the substrate; and an insulating encapsulation (an epoxy resin for instance, visible in
The designation “leadframe” (or “lead frame”) is currently used (see, for instance the USPC Consolidated Glossary of the United States Patent and Trademark Office) to indicate a metal frame that provides support for an integrated circuit chip or die as well as electrical leads to interconnect the integrated circuit in the die or chip to other electrical components or contacts.
Essentially, a leadframe 12 comprises an array of electrically-conductive formations (or leads) 12B that from an outline location extend inwardly in the direction of a semiconductor chip or die (such as, 14A or 14B, for instance) thus forming an array of electrically-conductive formations from a die pad 12A configured to have at least one semiconductor chip or die attached thereon. This may be via conventional means such as a die attach adhesive (a die attach film (DAF), for instance).
In certain cases, a leadframe can be of the pre-molded type, that is a type of leadframe comprising a sculptured metal (e.g., copper) structure formed by etching a metal sheet and comprising empty spaces that are filled by a resin “pre-molded” on the sculptured metal structure.
The current transferred from the high-power section to the output pads 12B of the device can be significant. As shown on the right-hand side of
That is, as illustrated in
Conversely, clips 28 are used to couple the high-power section (right-hand side of
According to a conventional approach, clips 28 as illustrated, for instance, in
Clips are conventionally provided with centering features that facilitate mounting and keeping clips 28 in position during processing. Pins may be provided, via punching for instance, at the terminal portion of the clips which will be coupled to respective leads 12B provided with recessed portions at corresponding locations.
Due to the relatively small dimensions of current semiconductor devices, centering features, such as pins, are increasingly difficult to provide via conventional stamping tools. In certain devices, pins cannot be provided when more than two power channels are desired.
According to another conventional approach, ribbons, that is, electrically conductive (of a metallic material such as copper or a copper alloy, for instance) strip-like formations, are used to provide the desired (power) electrical couplings between a power semiconductor die 14B and power leads 12B.
The terminal parts of the ribbons may be bonded to the underlying die bonding pads 18 or leads 12B via ultrasonic wedge-bonding technique in order to form the desired electrical couplings and to keep the ribbons in position during processing of the devices.
Ultrasonic wedge-bonding is essentially based on the application of ultrasound and (mechanical) pressure to form an electrical connection between the terminal part of a ribbon and an underlying surface.
While advantageous for certain aspects, wedge-bonding may have undesired effects on the device structure as a consequence of the mechanical stress applied during bond formation.
The mechanical stress applied in the wedge bonding step may have detrimental effect on both the leadframe 12 and the semiconductor die 14B, possibly resulting in deformation of the leadframe 12 and/or cratering of the semiconductor die 14B at the die bonding pad 18 thereof. Such undesired effects may cause failure and rejection of the device under processing.
In solutions as described herein, an electrical coupling member is provided to electrically couple a semiconductor die to one or more (power) leads.
In solutions as described herein, an electrical coupling member may be provided via premolding technology.
Solutions as described herein contemplate providing a leadframe, mounting a die thereon, applying an electrical coupling member to form electrical connections between the die and leads in the leadframe.
An electrical coupling member as described herein may be formed via pre-molding techniques, similar to processing to provide pre-molded leadframe.
As known to those skilled in the art, in the manufacturing process of pre-molded leadframes, a plurality of individual leadframes may be arranged in a leadframe reel (that is, a common substrate) to facilitate concurrent processing thereof.
In a similar way, a plurality of coupling members 100 may be concurrently processed by providing a coupling reel 1000 as illustrated in
As illustrated in
An elongated main body 101 of electrically insulating pre-molding compound 20 is supported by the outer frame and divides the region comprised in the outer frame into two empty regions 103.
The main body 101 is provided with electrically metal (copper, for instance) pads 102 exposed, that is, left uncovered by the pre-molding compound 20, at a first surface of the main body 101 of electrically insulating compound 20.
As mentioned, conventional pre-molding techniques may be used to form a coupling reel 1000 having reel portions as illustrated in
As exemplified in the figure, two ribbons 108 may be attached to each metal pad 102 exposed at the first surface of the main body 101 of the coupling member 100. Ribbons 108 may be attached via conventional (ultrasonic) wedge-bonding techniques, for instance.
More in detail, a first ribbon 108 may be wedge-bonded at its (proximal) terminal portion on a metal pad 102 exposed at the first surface of the main body 101. A second ribbon 108 may be wedge-bonded on the terminal end of the first ribbon 108 (wedge-on-wedge) previously welded on the metal pad 102, as illustrated in
In the exemplary case, two ribbons 108 are attached to each of the four metal pads 102 in order to provide, as described in the following, four (high-current) electrical couplings between the semiconductor die 14B and the leads 12B.
For simplicity and ease of explanation, the case will be considered in the following description of a coupling member 100 with four high-current electrical couplings. This is by way of example only, as a different number or a different layout of couplings may be suggested by device design.
Cutting (with a saw or blade, for instance) along cutting lines referenced with the reference CL in
As illustrated in
Said otherwise, a coupling member 100 as described herein comprises (at least) one electrically conductive pad 102 having first and second electrically conductive ribbons 108 protruding therefrom, the first and second electrically conductive ribbons 108 having proximal ends at the electrically conductive pad 102 and distal ends away from the electrically conductive pad 102.
The distal ends of the first and second electrically conductive ribbons 108 are configured to be electrically coupled to a semiconductor die (such as the semiconductor die 14B) arranged at the die mounting location 12A of the leadframe 12 and to the (at least one) electrically conductive lead 12B, respectively.
The electrical coupling member 100 may comprise an electrically insulating body 101 that leaves the electrically conductive pads 102 exposed at a side portion of the electrically insulating body 101. The proximal ends of the first and second electrically conductive ribbons 108 are arranged at the side portion of the electrically insulating body 101 where the electrically conductive pads 102 are left exposed.
As illustrated, size and dimension of the coupling member 100 and its parts as well as the position of metal pads 102 (and consequently, the position of the ribbons 108) may be chosen in such a way to match the position of the die bonding pads 18 and the leads 12B and the distance therebetween.
The distal terminal portions of the ribbons 108 are attached to the die bonding pads 18 and the leads 12B by providing solder material SM thereon.
As illustrated in
It may be appreciated that handling, centering and keeping in position a coupling member 100 as described herein is considerably easier than individual clips. Moreover, the coupling member 100 may be provided with centering features (such as pins, not illustrated in the figures for simplicity) in order to facilitate positioning of the coupling member 100.
In summary, a manufacturing process as described herein comprises: arranging a semiconductor die 14B at a die mounting location (that is, a die pad) 12A of a substrate (a leadframe, for instance) 12, where the substrate 12 comprises an array of electrically conductive leads 12B arranged laterally of the die mounting location 12A; electrically coupling the semiconductor die 14B arranged at the die mounting location 12A of the substrate 12 with one (or more) electrically conductive lead(s) 12B in the array of electrically conductive leads 12B via an electrical coupling member 100 applied onto the semiconductor die 14B.
The electrical coupling member 100 comprises one (or more) electrically conductive pad(s) 102 having first and second electrically conductive ribbons 108 protruding therefrom. The first and second electrically conductive ribbons 108 have their proximal ends at the electrically conductive pad 102 and their distal ends away from the electrically conductive pad 102.
The distal ends of the first and second electrically conductive ribbons 108 are thus electrically coupled to the semiconductor die 14B arranged at the die mounting location 12A of the substrate 12 and to the electrically conductive lead 12B, respectively, to provide electrical coupling therebetween.
Further processing of an (integrated circuit) semiconductor device as illustrated in
As mentioned, concurrent processing of a plurality of coupling members 100 may involve providing a coupling reel comprising a plurality of such coupling members 100.
As illustrated, a coupling reel 1000 comprising a plurality of coupling members 100 may be mounted on a leadframe reel 1200; each coupling reel 1000 portion (comprising an individual coupling member 100) may be matched to a corresponding leadframe reel 1200 portion (comprising an individual leadframe 12).
Such a processing step may be facilitated by providing the reels 1000, 1200 with centering features such as pins and corresponding recessed portions (not visible for simplicity).
After applying the coupling reel 1000 on the leadframe reel 1200, the desired electrical couplings may be provided for each portion of the reels by electrically couple the distal ends of the ribbons 108 of the individual coupling members 100 comprised in the coupling reel 1000 to the die bonding pads 18 and leads 12B of the corresponding individual leadframe 12 comprised in the leadframe reel 1200, similarly to what has been discussed in the case of an individual coupling member 100 mounted on an individual leadframe 12.
The reels 1000, 1200 may be further processed in order to concurrently process a plurality of devices and finally singulated in order to obtain a plurality of individual, processed devices.
Ribbons 108 may be attached to die bonding pads 18 and leads 12B as described in the foregoing, that is, providing solder material SM such as a solder paste or glue.
As illustrated in
Such a coupling member 100 may be applied to a semiconductor die 14B with the first surface of the main body 101 facing the semiconductor die 14B, as illustrated in
As illustrated in
That is, the electrical coupling member may be formed in such a way that the electrically insulating body 101 leaves the electrically conductive pads 102 exposed at a further side portion of the electrically insulating body 101 opposite the side portion at which the proximal ends of the first and second electrically conductive ribbons 108 are arranged.
The insulating encapsulation 22 molded onto the semiconductor die 14B and onto the electrical coupling member 100 may leave uncovered the electrically conductive pads 102 exposed at the further side portion of the electrically insulating body 101.
Such a short circuit may be obtained by providing a third ribbon 108 electrically coupling two neighboring metal pads 102.
In the example illustrated in
The claims are an integral part of the technical teaching provided in respect of the embodiments.
Without prejudice to the underlying principles, the details and embodiments may vary, even significantly, with respect to what has been described by way of example only without departing from the extent of protection. The extent of protection is determined by the annexed claims.
Number | Date | Country | Kind |
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102023000017700 | Aug 2023 | IT | national |