Power semiconductor component and method for producing a power semiconductor component

Abstract

The invention relates to a power semiconductor component (1), having: - a substrate (2); - at least one power semiconductor chip (3) arranged on the substrate (2), and - a plastic housing (4) which embeds the power semiconductor chip (3) and at least part of the substrate (2), wherein on an upper side (8) of the plastic housing (4), which upper side forms an outer side of the power semiconductor component (1), a metal structure (10) is arranged at least above the power semiconductor chip (3), said metal structure being applied by means of the plasma coating method and being electrically insulated from the power semiconductor chip (3).

Description

[0001] Description

[0002] Power semiconductor component and method for producing a

[0003] Power semiconductor component

[0004] The present invention relates to a power semiconductor component with a plastic housing. It also relates to a method for producing such a power semiconductor component.

[0005] Various designs exist for power semiconductor components with at least one power semiconductor chip. For example, they can be designed as molded modules, with the at least one power semiconductor chip arranged on a substrate and a molded plastic housing embedding the power semiconductor chip and at least a portion or regions of the substrate.

[0006] To increase the performance of electronic systems, silicon components are increasingly being replaced with silicon carbide-based components. This enables higher power densities and thus component miniaturization. This has the advantage of saving material and costs. However, it also results in smaller surfaces available for electrical contact. This results in significantly increased requirements for current density and current-carrying capacity for top-side contacting.

[0007] The plastic housing made of organic material can rupture due to faults on the circuit board that trigger thermal events. Decomposition of the organic material begins at temperatures of approximately 350 °C. Failure of the housing means that the surrounding installation space is no longer protected from critical temperatures. The power required to reach this decomposition temperature may be only a few watts, and power limitation is not possible for all components.

[0008] It is therefore an object of the present invention to provide a power semiconductor component in which, despite a high power density, the temperature increase in the ambient temperature is limited in the event of a fault. Furthermore, a method for producing such a power semiconductor component is to be provided. This object is achieved by the subject matter of the independent claims.

[0009] Advantageous embodiments and further developments are the subject of the subclaims.

[0010] According to one aspect of the invention, a power semiconductor component is specified, comprising a substrate, at least one power semiconductor chip arranged on the substrate, and a plastic housing that embeds the power semiconductor chip and at least a part or regions of the substrate. On an upper side of the plastic housing forming an outer side of the power semiconductor component, a metal structure that is applied using a plasma coating process and is electrically insulated from the power semiconductor component is arranged at least above the power semiconductor chip. The plastic housing is formed, in particular, from a molding compound or an injection molding compound, which is shaped by (direct) molding or injection molding of the molding compound or injection molding compound onto the substrate or a part thereof and onto the power semiconductor chip, and completely encloses the substrate or at least a part thereof and the power semiconductor chip.

[0011] The power semiconductor component thus has a metal structure on the top side of the housing that does not act as a conductor or similar and is not in contact with the power semiconductor chip or other electronic components of the power semiconductor component. The metal structure is thus arranged only on the top side of the plastic housing and is not connected to the power semiconductor chip through the plastic housing.

[0012] The power semiconductor component has the advantage that the metal structure reduces the risk of heat or flames escaping to the outside in the event of a sharp rise in temperature of the power semiconductor chip and damage to the plastic housing. The increased thermal conductivity of the metal structure dissipates heat, preventing the temperature outside the plastic housing from becoming too high. Furthermore, flames are prevented from spreading to the surrounding area. Thus, the power semiconductor component incorporates a safety feature to protect the surrounding area in the event of thermal events on the power semiconductor chip.

[0013] The metal structure is applied using a plasma coating process. In this process, especially the fine powder coating (FPC) process, fine metal particles are introduced into a plasma jet and then applied to the surfaces to be coated. This process allows for the application of finely structured layers of highly thermally conductive material.

[0014] The metal structure can extend substantially across the entire top surface of the plastic housing. Alternatively, it can be limited to a portion of the top surface, for example, to an area above the power semiconductor chip.

[0015] The metal structure can, for example, be designed as a lattice structure. It can also be designed as a spiral structure or meander structure, or have another regular or irregular shape.

[0016] According to one embodiment, a plastic layer, also applied using a plasma coating process, is arranged on the top side of the metal structure. This plastic layer can be made of PEEK (polyetheretherketone) or PA (polyamide), for example. This plastic layer, which can also be applied over the entire surface, insulates and protects the metal structure from the outside. The plastic used can, in particular, be a high-temperature-resistant plastic.

[0017] The metal structure can be connected to a ground terminal of the power semiconductor component.

[0018] According to a further aspect of the invention, a method for producing a power semiconductor component is specified, comprising providing a power semiconductor component with at least one power semiconductor chip arranged on a substrate and a plastic housing which embeds the power semiconductor chip and at least a part or regions of the substrate, and applying a metal structure electrically insulated from the power semiconductor component to an upper side of the plastic housing in a plasma coating process.

[0019] The process offers the advantages already described in connection with the power semiconductor component. Furthermore, the metal structure can be applied particularly easily and precisely as a security device using the plasma coating process. The temperature input during the FPC process is very low at less than 100°C and is unproblematic for the materials involved. The FPC process also places no mechanical stress on the component. This makes it more gentle than, for example, cold gas deposition. Furthermore, the shape, extent, and thickness of the metal structure can be freely selected and easily changed at any time. The top side of the plastic housing, to which the metal structure is applied, does not need to be flat. It can also be curved, inclined, or structured.

[0020] Because the metal structure is applied to the top of the plastic housing, it has a defined insulating distance from the semiconductor chip and does not need to be taken into account when designing the molding tool.

[0021] According to one embodiment, at least one stencil is used to pattern the metal structure. Using a stencil allows for the creation of fine structures and the achievement of good edge sharpness.

[0022] According to one embodiment, the top surface of the plastic housing is prepared for better adhesion prior to plasma coating by heating, grinding, blasting, laser roughening, and / or plasma activation. This has the advantage that the metal structure can also be applied to plastic housings made of materials to which the adhesion of the metal powder is unsatisfactory.

[0023] In particular, copper, iron and aluminum or other metals or alloys with good thermal conductivity are suitable materials for the metal structure.

[0024] Embodiments of the invention are described below by way of example with reference to schematic drawings.

[0025] Figure 1 shows a sectional view of a power semiconductor component according to a first embodiment of the invention;

[0026] Figure 2 shows a top view of the power semiconductor component according to Figure 1;

[0027] Figure 3 shows a top view of a power semiconductor component according to a second embodiment;

[0028] Figure 4 shows a top view of a power semiconductor component according to a third embodiment, and Figure 5 shows a sectional view of a power semiconductor component according to a fourth embodiment.

[0029] Figure 1 shows a power semiconductor component 1 with a substrate 2 having a bottom side 5 and a top side 6. At least one power semiconductor chip 3 is arranged on the top side 6. The power semiconductor chip 3 and at least regions of the substrate 2, in particular its top side 6, are embedded in a plastic housing 4. External contacts 7 of the power semiconductor component 1 extend from the plastic housing 4.

[0030] A top side 8 of the plastic housing 4 forms a top side of the power semiconductor component 1. A metal structure 10 is applied to the top side 8 above the power semiconductor chip 3 using a plasma coating process.

[0031] The metal structure 10 is electrically insulated from the power semiconductor chip 3. It therefore does not serve to contact the power semiconductor chip 3. The electrically insulated metal structure 10 is formed, for example, from copper or aluminum and is arranged in the area where the plastic housing 4 would fail and possibly ignite in the event of an increased temperature development at the power semiconductor chip 3.

[0032] Figure 2 shows a top view of the power semiconductor component 1 according to Figure 1. This view shows that the metal structure 10 is formed as a grid structure. Such a grid structure can be applied with a very fine structure and sharp boundaries using a plasma coating process, for example, using stencils.

[0033] In the embodiment shown, the metal structure 10 has dimensions a, b that approximately correspond to those of the power semiconductor chip 3. Thus, the metal structure 10 only covers the portion of the top side 8 where the plastic housing 4 would fail in the event of overheating of the power semiconductor chip 3. This saves material and thus costs for the metal structure 10.

[0034] Figure 3 shows a power semiconductor component 1 according to a further

[0035] Embodiment. This differs from the one shown in Figures 1 and 2 in that the metal structure 10 extends substantially over the entire top side 8 of the plastic housing 4. Such a configuration of the metal structure 10 can be selected if the power semiconductor component 1 has multiple power semiconductor chips 3 or if, for other reasons, increased heat development is also expected in other areas of the top side 8.

[0036] Figure 4 shows a further embodiment of the power semiconductor component 1. In this embodiment, the metal structure 10 is arranged only above a power semiconductor chip 3 and has a spiral structure. Furthermore, it has a connection 11 for electrically contacting the spiral structure 10. In this embodiment, the metal structure 10 can be used, if necessary, to heat the power semiconductor chip 3 arranged underneath. However, in the event of an increased temperature development at the power semiconductor chip 3, it serves, just like the metal structures 10 in the previously described embodiments, to limit the temperature in the environment and prevent flames from escaping from the plastic housing 4 in the event of a failure of the plastic housing 4.

[0037] Figure 5 shows a further embodiment of a power semiconductor component 1. In this embodiment, too, the metal structure 10 is formed as a spiral structure with an electrical connection 11. However, an insulating layer 12 is additionally applied to the metal structure 10. The insulating layer 12 is made of plastic, which was also applied to the metal structure 10 and the top side 8 of the plastic housing 4 using a plasma coating process.

[0038] List of reference symbols

[0039] 1 power semiconductor component

[0040] 2 Substrate 3 Power semiconductor chip

[0041] 4 plastic housings

[0042] 5 Bottom

[0043] 6 Top

[0044] 7 External contacts 8 Top

[0045] 10 Meta II Structure

[0046] 11 Connection

[0047] 12 insulating layer

Claims

Patent claims 1. Power semiconductor component (1 ), comprising - a substrate (2); - at least one power semiconductor chip (3) arranged on the substrate (2) and - a plastic housing (4) which embeds the power semiconductor chip (3) and at least part of the substrate (2), wherein on an upper side (8) of the plastic housing (4) forming an outer side of the power semiconductor component (1), at least above the power semiconductor chip (3), a metal structure (10) which is applied by a plasma coating process and is electrically insulated from the power semiconductor chip (3) is arranged.

2. Power semiconductor component (1) according to claim 1, wherein the metal structure (10) extends substantially over the entire upper side (8) of the plastic housing (4).

3. Power semiconductor component (1) according to claim 1, wherein the metal structure (10) is limited to a region above the power semiconductor chip (3).

4. Power semiconductor component (1) according to one of claims 1 to 3, wherein the metal structure (10) is designed as a lattice structure.

5. Power semiconductor component (1) according to one of claims 1 to 3, wherein the metal structure (10) is designed as a spiral structure.

6. Power semiconductor component (1) according to one of claims 1 to 5, wherein an electrically insulating plastic layer (12) applied by a plasma coating process is arranged on an upper side of the metal structure (10).

7. Power semiconductor component (1) according to claim 6, wherein the plastic layer (12) applied in the plasma coating process is made of PEEK or PA.

8. Power semiconductor component (1) according to one of claims 1 to 7, wherein the metal structure (10) is connected to a ground terminal of the power semiconductor component (1).

9. Power semiconductor component (1) according to one of claims 1 to 8, wherein the metal structure (10) is designed as a heating structure and has a contact terminal (11) for applying an electrical voltage.

10. A method for producing a power semiconductor component (1), comprising providing a power semiconductor component (1) with at least one power semiconductor chip (3) arranged on a substrate (2) and a plastic housing (4) which embeds the power semiconductor chip (3) and at least part of the substrate (2), and applying a metal structure (10) electrically insulated from the power semiconductor chip (3) to an upper side (8) of the plastic housing (4) in a plasma coating process.

11. The method according to claim 10, wherein at least one template is used to structure the metal structure (10).

12. The method according to claim 10 or 11, wherein the upper side (8) of the plastic housing (4) is prepared for better adhesion before plasma coating by heating, grinding, blasting, laser roughening and / or plasma activation.

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