Electronic component with metal cap

Abstract

The present invention relates to electronic components with metal caps. The present disclosure describes an electronic component that includes a package having a top side and a bottom side and at least one electronic die housed within an enclosure inside the package. The package includes a package base on its top side and a metal cap on its bottom side. The at least one electronic die is separated from the metal cap by a gap, and the metal cap is attached to the package base to form the enclosure.

Description

TECHNICAL FIELD

[0001] The present invention relates to electronic components, in particular component packages around electronic chips. The present disclosure also relates to electronic components in which the component package comprises a base and a cap attached to the base. BACKGROUND

[0002] Electronic chips, also referred to as dies, are usually prepared by manufacturing various electronic structures on a substrate and cutting the substrate into chip-sized pieces. Each chip can then be placed inside a protective package that forms an enclosure in which the chip is protected from the surrounding environment. The chip can be mechanically attached to a support structure inside the enclosure, such as a die pad, and electrically connected to contacts that extend outside the enclosure. The packaged chip thus forms an electronic component that can be mounted on a circuit board.

[0003] The protective package can comprise a package base with a die pad to which the electronic chip can be attached. A separate cap can then be attached to the package base to seal the electronic chip inside an enclosure formed by the base and the cap. When the component is mounted to the surface of a circuit board, the package base is attached to the circuit board. The document US2005101161 discloses a package with a base and a cap. This arrangement can be problematic in some applications in which the electronic chip is sensitive to external vibrations. The protective package can resonate at a frequency that affects the operation of the chip. SUMMARY

[0004] It is an object of the present disclosure to provide a device that alleviates the above-mentioned drawbacks.

[0005] The object of the present disclosure is achieved by a device having the features specified in the independent claims. Preferred embodiments of the present disclosure are disclosed in the dependent claims.

[0006] The present disclosure is based on the idea of constructing an inverted protective package that can be mounted to a circuit board, in which the cap is closer to the surface of the circuit board than the base. By attaching the cap to the circuit board in a suitable manner, the resonant frequency of the protective package can be shifted to a frequency that does not interfere with the electronic chip. BRIEF DESCRIPTION OF DRAWINGS

[0007] The present disclosure will be described in more detail by preferred embodiments with reference to the attached drawings, in which:

[0008] Figure 1a An electronic component is shown.

[0009] Figure 1b An electronic component with a metal cap is shown.

[0010] Figure 1cAn electronic chip inside the enclosure formed between the package base and the metal cap is shown.

[0011] Figure 2 A bottom side of the metal cap is shown.

[0012] Figure 3a A circuit board with electronic components is shown.

[0013] Figure 3b A bottom side of the metal cap is shown.

[0014] Figure 4a A circuit board including electronic components is shown.

[0015] Figure 4b A layered structure is shown. DETAILED DESCRIPTION

[0016] The present disclosure describes an electronic component including a package having a top side and a bottom side and at least one electronic chip housed inside an enclosure within the package. The package includes a package base at its top side. The package base includes a chip mounting element with at least one electronic chip attached therein. The package further includes a metal cap at its bottom side. The at least one electronic chip is separated from the metal cap by a gap, and the metal cap is attached to the package base to form the enclosure.

[0017] In the figures of the present disclosure, the plane defined by the x-axis and the y-axis is parallel to the plane of a circuit board to which the electronic component will be attached. The direction defined by the z-axis is perpendicular to the same circuit board plane, and to the bottom side of the metal cap.

[0018] The words "bottom" and "top" refer here only to how the component is placed on a circuit board. The bottom side of the component is intended to be attached to the surface of the circuit board. Words such as "above" and "below" have the same meaning - a first part that is above a second part is closer to the top side of the component than the second part. Words such as "bottom" and "top", "above" and "below" do not refer to the direction of the component relative to the direction of the Earth's gravitational field when the component is manufactured or used, although they can coincide with this traditional top / bottom meaning when the xy-plane is horizontal.

[0019] Figure 1aAn electronic component is shown with a package base 111 that houses a plurality of electronic chips 13 attached to a chip mounting element 12. The component also has a plurality of electronic leads 14 that can be used to make electrical connections with the chips 13 outside of the package. In other words, the chips 13 can be connected to electronic leads 14 inside the package, for example, by wire bonding, and the electronic leads 14 can extend outward from the package base in a side direction that is substantially perpendicular to the z-axis. Electrical connections with the chips 13 can then be made by connecting the leads 14 to appropriate connectors.

[0020] The chip mounting element 12 can be located in a recessed area of the package base so that the package base 111 forms a set of side walls that at least partially surround the chips 13. Figure 1a A metal cap is not shown in. It can be placed over the chip mounting element 12 so that the electronic chips 13 are enclosed between the package base 111 and the metal cap.

[0021] Figure 1b An electronic component 19 and a circuit board 15 that includes the electronic component are shown. The electronic component includes a package base 111 and a metal cap 112 that together form an enclosure. The metal cap 112 forms a bottom side of the package. The metal cap 112 of the electronic component can be attached to a surface of the circuit board 15. Components inside the enclosure are not shown in this figure. In Figures 1a to 1c , the z-axis shows a "top" direction. In other words, Figure 1a The perspective view shows the component upside down. The chip mounting element 12 is located on a bottom side of the package base 111 and the electronic chips 13 are attached to the chip mounting element 12 on the bottom side of the package base 111. The direction is then reversed when the electronic component is placed on a circuit board, as Figure 1b is shown.

[0022] The package base 111 can be made of plastic, for example, and can be manufactured in a molding process in which the base 111 is molded around a lead frame that has already formed the chip mounting element 12 and the electronic leads. Other methods can also be used to form the plastic package base. The package base can instead be made of a ceramic material. The metal cap 112 can be attached to the package base 111 with glue or any other method. The area of attachment in which the metal cap is attached to the package base can encircle the enclosure.

[0023] The metal cap can be attached to a surface of the circuit board 15 at one or more attachment points 161, as Figure 1b is shown. The attachment can be performed, for example, by soldering or using an adhesive. Figure 1cAn electronic chip 13 inside the enclosure 17 formed between the package base 111 and the metal cap 112 is schematically shown. The electronic chip 13 is separated from the metal cap by a gap 18. The gap 18 can be an air gap, for example.

[0024] As shown in Figure 1b and Figure 1c the metal cap 112 can be shaped such that a bottom surface of the metal cap 112 is below the attachment area where the metal cap 112 is attached to the package base 111. In other words, the metal cap 112 can be shaped such that at least a portion of the enclosure is formed by the cap 112. The shape of the enclosure 17 and the height of the gap 18 are then determined by the shape of the metal cap 112 and the shape of the package base 111 and the mounting elements inside it. As shown in Figure 1a the chip mounting elements can be recessed relative to the edges of the package base 111 (in the positive z-direction) where the base 111 and the metal cap are attached to each other. The shape of the enclosure 17 and the height of the gap 18 are then determined by the shape of the recess and the shape of the metal cap 112.

[0025] The electronic leads 14, which can also be referred to as electrical contacts, can extend to the surface of the circuit board 15 and to the electrical contact pads 162 on the surface of the circuit board. As seen in Figure 1b the electronic leads 14 can extend substantially to the same z-coordinate as the bottom surface of the metal cap 112.

[0026] A viscoelastic material can be used to influence the resonance frequency and amplitude of the package, either within the package itself or between the electronic components and the circuit board to which they are attached. The metal cap can comprise a viscoelastic material sandwiched between two metal layers, for example. In other words, the manufacturing of the cap can comprise a lamination process where a viscoelastic material is laminated between two metal sheets, followed by a shaping process where the laminated structure is shaped into the form of the cap. Alternatively or additionally, a viscoelastic adhesive can also be used to attach the metal cap to the package base.

[0027] There are different options that can be used to facilitate the mechanical connection of the electronic components to the circuit board. For example, the entire bottom of the metal cap can be coated with a solder pad material to form a solder pad that extends substantially across the entire bottom of the metal cap, or dedicated areas of the metal cap can be coated with a solder pad material to form solder pads only in these areas. The solder pad(s) on the metal cap can then be attached to one or more solder pads on the surface of the circuit board with a solder material.

[0028] Alternatively, the metal cap can be attached to the solder pads on the surface of the circuit board with an adhesive and a solder material. The adhesive can be in contact with the metal cap and the metal plate can be placed between the adhesive and the solder material of the solder pads that fix the cap to the circuit board. The adhesive can be a viscoelastic material. The viscoelastic material can be attached directly to the metal cap, or to an attachment pad formed from the solder pad material or any other suitable material on the metal cap.

[0029] Another alternative is to coat one or more areas on the bottom of the metal cap with the solder pad material to form solder pads in said one or more areas on the bottom of the metal cap. These solder pads on the metal cap can then be attached to the surface of the circuit board with a solder material. Corresponding solder pads can be present on the surface of the circuit board. Another alternative is to form solder pads on the surface of the circuit board and solder them directly to the metal cap without forming separate solder pads on the metal cap for this purpose. Depending on the materials chosen, the solder attachment can be made with or without solder pads on the side of the metal cap and with or without solder pads on the circuit board.

[0030] Figure 2 The bottom of an electronic component with a metal cap on its bottom is schematically shown. Reference 212 corresponds to reference 112 in Figure 1b and Figure 1c . The solder attachment areas 221 are shown on the bottom side of the metal cap. These areas on the metal cap can but do not necessarily have to include solder pads.

[0031] The (typically very stiff) solder attachment between the metal cap and the surface of the circuit board (with or without solder pads) can be combined with a viscoelastic attachment between the same cap and the circuit board. The rigid solder attachment will typically increase the resonance frequency of the metal cap that is fixed on the circuit board, while the viscoelastic attachment will dampen the amplitude of any oscillations experienced by the metal cap.

[0032] Figure 3a A circuit board 35 with an electronic component 39 is shown. The electronic component has a metal cap 312 on its bottom side. The component 39 has been separated from the circuit board 35 to keep things clear, but it is in mechanical contact with the circuit board when it is attached.

[0033] The metal cap 312 can include one or more first attachment areas 341 and one or more second attachment areas 342. The surface of the circuit board 35 can include corresponding one or more first attachment areas 351 and one or more second attachment areas 352 that are aligned with the one or more first attachment areas 341 and the one or more second attachment areas 342 on the metal cap 312, respectively. The one or more first attachment areas 341 on the metal cap 312 can be attached to the one or more first attachment areas 351 on the surface of the circuit board 35 with a solder material. The one or more second attachment areas 342 on the metal cap 312 can be attached to the one or more second attachment areas 352 on the surface of the circuit board 35 with a viscoelastic adhesive material.

[0034] Both the first attachment areas 351 and the second attachment areas 352 on the surface of the circuit board 35 can include solder pads. The first attachment areas 341 and the second attachment areas 342 on the metal cap do not necessarily need to include attachment pads, but can also form solder pads or other attachment pads on the cap, as described above.

[0035] The one or more second attachment areas 352 on the surface of the circuit board can include solder pads, and the one or more second attachment areas 342 on the metal cap can include a metal layer that is secured to the metal cap using a viscoelastic adhesive. The metal layer can then be secured to the solder pads in the second attachment areas 352 using a solder material. In other words, the metal cap can be attached to the one or more second attachment areas 352 on the surface of the circuit board 35 by a layered structure that includes a layer of viscoelastic adhesive material closest to the metal cap 312, a layer of solder material closest to the solder pads in the second attachment areas 352 on the surface of the circuit board 35, and a layer of metal between the layer of viscoelastic adhesive material and the layer of solder material.

[0036] Figure 3b A bottom surface of the metal cap 312 in the xy-plane is shown, and one possible placement of the one or more first attachment areas 341 and the one or more second attachment areas 342 on this surface is shown. Other placement geometries and relative dimensions are possible.

[0037] Figure 4a A circuit board including electronic components is shown. Reference numerals 412, 45, and 49 correspond to reference numerals 312, 35, and 39 in Figure 3a A layered structure 40 for attaching a metal cap to a surface of a circuit board is shown. Figure 4bThe layered structure 40 is shown in more detail. It comprises a solder pad 401 on the surface of the circuit board 45, a metal layer 403 and a layer of solder material 402 attaching the metal layer 403 to the solder pad 401. The layered structure further comprises a layer of viscoelastic adhesive material 404 attaching the other side of the metal layer 403 to the metal cap 412. Figure 4a A second attachment structure 41 is also shown, in which a solder pad on the metal cap 412 is attached to a solder pad on the surface of the circuit board by a layer of solder material. The layered structure 40 is thicker than the attachment structure 41, but the metal cap comprises a bump 42 extending in the z-direction to compensate for this difference.

Claims

1. An electronic component comprising a package having a top side and a bottom side, and at least one electronic chip housed within a housing inside said package. Its features are, The package includes a package base on its top side, and the package base includes a chip mounting element for attaching at least one electronic chip. The package also includes a metal cap on its bottom side, wherein the at least one electronic chip is separated from the metal cap by a gap, and the metal cap is attached to the package base to form the housing. The metal cap has a bottom surface with its z-axis perpendicular to it, and the bottom surface of the metal cap forms the bottom side of the package. The component also includes one or more electrical contacts capable of making electrical connections with the at least one electronic chip, and the electrical contacts extend outward from the package base to the same z-coordinate as the bottom surface of the metal cap.

2. The electronic component according to claim 1, characterized in that, The metal cap includes a viscoelastic material sandwiched between two metal layers.

3. The electronic component according to any one of claims 1-2, characterized in that, The entire bottom of the metal cap is coated with a welding pad material to form a welding pad that extends substantially across the entire bottom of the metal cap.

4. The electronic component according to any one of claims 1-2, characterized in that, One or more areas on the bottom of the metal cap are coated with a welding pad material to form welding pads in the one or more areas on the bottom of the metal cap.

5. A circuit board comprising the electronic components according to any one of claims 1-4, characterized in that, The metal cap of the electronic component is attached to the surface of the circuit board.

6. The circuit board according to claim 5, characterized in that, The metal cap includes one or more first attachment regions and one or more second attachment regions, and the surface of the circuit board includes one or more corresponding first attachment regions and one or more second attachment regions aligned with the one or more first attachment regions and one or more second attachment regions on the metal cap, respectively, and the one or more first attachment regions on the metal cap are attached to the one or more first attachment regions on the surface of the circuit board by soldering material, and the one or more second attachment regions on the metal cap are attached to the one or more second attachment regions on the surface of the circuit board by viscoelastic adhesive material.

7. The circuit board according to claim 6, characterized in that, One or more second attachment regions on the surface of the circuit board include solder pads, and one or more second attachment regions on the metal cap are attached to one or more second attachment regions on the surface of the circuit board via a layered structure, the layered structure including a viscoelastic adhesive layer closest to the metal cap, a solder material layer for the solder pads in the second attachment regions closest to the surface of the circuit board, and a metal layer between the viscoelastic adhesive layer and the solder material layer.

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