Method for producing an electronics component, and electronics component

Abstract

The present invention is in the field of electrical engineering and relates to a method for producing an electronics component having at least one electronics element (12) that is electrically connected by wire bonding to a segment (14.1) of a strip (4) consisting of a substrate material, wherein: the strip (4) is rolled by rolling a base material; the surface (8) formed by rolling is removed to form an exposed contact point (6), formed by the base material, on the strip; the rolled strip (4) is wound up to form a coil (10); the rolled strip (4) is unwound from the coil (10); the segment (14.1) is separated from the strip (4); and, in order to electrically connect the electronics element (12), a wire (16) is electrically conductively bonded to the contact point (6). The invention furthermore relates to an electronics component produced in accordance with the method and to a unit (18) which is ready for shipping and comprises the coil (10), which has an exposed contact point (6) on the strip (4) for a wire, at which contact point the surface (8) formed by rolling has been removed and the base material of the coil (10) has been exposed.

Description

[0001] Method for producing an electronic component and electronic component

[0002] The present invention lies in the field of electrical engineering and relates to an electronic component having at least one electronic component that is electrically connected to a segment of a strip of a carrier material by means of wire bonding, a method for producing such an electronic component and a coil that is formed by a strip of a carrier material and is provided for a wire bonding process within the scope of this production method.

[0003] The reliability and service life of contact systems in switching devices, electromechanical components, and electronic components often depend not only on the contact material used. The choice of the appropriate substrate material also plays a crucial role.

[0004] Copper-based materials are the most important substrate materials. Depending on the application, nickel-based materials or multilayer composite materials, such as thermobimetals, are also used.

[0005] The requirements placed on the substrate materials vary depending on their specific applications. For example, copper materials are required to exhibit not only high electrical and thermal conductivity, but also good strength properties even at elevated temperatures, as well as sufficiently high corrosion resistance. If the substrate materials are used as contact springs, the material must also exhibit good spring properties. Depending on the manufacturing process, a number of technological properties are also required, such as good hot and cold formability, machinability, punchability, weldability, solderability, and electroplating.

[0006] Materials made of copper and copper alloys intended for use in electrical engineering and electronics are generally specified in standards. The DIN-standardized carrier material of the present invention is, in particular, a material in accordance with DIN EN 1758.

[0007] In electronics and electrical engineering, such a substrate is typically used not only for conducting current, especially power current. Sometimes, electronic components such as transistors, light-emitting diodes, or photodiodes are also bonded directly to the substrate.

[0008] Wire bonding is an electrical connection technique in which a thin wire (e.g. AU, AI) with a diameter of 50 to 300 pm is welded to a flat metal surface or a semiconductor element surface by means of high-frequency mechanical excitation. This joining process is frequently used in semiconductor components for the electrical connection between the semiconductor and the system carrier, which is usually made from a copper alloy strip. The wire bonding process requires a defect-free surface. During rolling production of the carrier material, which is supplied in strip form as a wound ring / coil, the surface comes into contact with metallic tools (rollers, straightening rolls) and deflection rolls during many process steps. In the process, defects and particles on the tools or rolls can be transferred to the surface of the carrier material. In addition, relative movement between the windings of the coil, e.g.During transport, scratches and other defects in the surface can occur, making it unsuitable for the wire bonding process. To achieve the defect-free surface required for the wire bonding process, extensive measures are required in the production of the substrate material and in testing.

[0009] The present invention aims to provide a solution to the problems described above.

[0010] According to a first aspect, the present invention provides a method for producing an electronic component having at least one electronic part that is electrically connected to a segment of a strip made of a carrier material by wire bonding. In this method, the strip is rolled in a conventional manner by rolling a base material. The surface formed by rolling is removed to form a contact point exposed on the strip, which contact point is formed by the base material. The rolled strip is then wound into a coil. The contact point is usually formed before the coil is wound up, preferably at the feed rate predetermined by the rolling past a processing station where the contact point is formed. This contact point can be formed by machining and preferably in the rolling direction.

[0011] The coil produced in this way is then typically prepared for shipping as part of the overall process. For this purpose, the coil is placed on a transport pallet and secured or fastened with transport securing devices. The invention is based on the idea that the coil is manufactured in a metalworking shop, and the subsequent processing steps, in particular wire bonding for the electrical connection of the electronic component, are carried out in an electrical shop, and the coil is transported.

[0012] There, the rolled strip is unwound from the coil, and the segment is separated from the strip. To electrically connect the electronic component, a wire is then electrically conductively bonded at the contact point. This wire can be bonded at the same time as the electronic component. The coil is formed from a strip of carrier material. The strip is formed by rolling a base material and has a surface formed by rolling. According to the present invention, at least one contact point exposed on the strip is formed on the strip-shaped carrier material, at which contact point the surface formed by rolling has been removed. The contact point is accordingly lower in height than the surface formed by rolling. The contact point is therefore spaced from the surface formed by rolling towards the center of the carrier material. It exposes the base material of the coil and is formed by this base material.The contact point is preferably formed only locally on the strip, meaning that the contact point is otherwise completely or partially surrounded by the surface formed by rolling. The contact point can be formed as an elongated strip extending continuously in the rolling direction. In this case, the contact point is surrounded on one side, preferably on both sides, by the surface formed by rolling. The contact point can also be surrounded by the surface formed by rolling at specific points and thus completely.

[0013] The contact point serves to remove impurities and modifications to the base material caused by rolling close to the surface. This base material is free of indentations, scars and disruptive foreign particles at the contact point. This allows the topographical and material requirements of the wire bonding process to be taken into account. Even in the event that the wire bonding process requires a previously applied electroplated coating to the contact point, the conditions for the bonding process are significantly improved compared to those with a rolled surface. Since the contact point is also deeper than the surface formed by rolling, the contact point cannot be affected by the relative movement of adjacent turns during transport. A carrier material with a defined contact point can then be supplied to a processor of the carrier material in the form of a coil with a large number of turns in the electronics or semiconductor industries.Electrical engineering is supplied.

[0014] One of the contact points is usually located on one or possibly two opposing surfaces of the strip, which are formed by rolling. This term is intended to express that the strip has two main side surfaces that extend significantly further than the end faces connecting these main side surfaces. These end faces can also be machined by rolling, but they are not necessarily formed by rolling. At least one contact point is located on the main side surface.

[0015] It is understood that, with a view to mass production and the use of a coil in such a production, the contact points are formed at fixed locations on the strip, usually at cyclical spacing from one another. This allows the respective electrically conductive carriers for use in electronics or electrical engineering to be separated from the coil from lengths of the strip-shaped carrier material. The contact point is usually located between the individual cut edges, through which a length of the strip is insulated from the coil.

[0016] As previously mentioned, the base material is preferably a copper alloy. The strip preferably complies with the specifications of DIN EN ISO 1758.

[0017] As mentioned previously, the contact point is located deeper than the rolling surface. The contact point is typically between 30 pm and 150 pm from the rolling surface.

[0018] At the contact point, the material forming the surface formed by rolling is preferably removed by machining.

[0019] This can preferably be done by skiving or scraping the surface of the finished rolled strip material. During skiving or scraping, the tool is stationary. The workpiece is moved relative to it. In contrast to milling, this type of material processing does not produce any visible structures on the surface perpendicular to the rolling direction. These structures perpendicular to the rolling direction can be disadvantageous for the bonding process, since the wire is also bonded to the surface perpendicular to the rolling direction. The present invention therefore also relates to a coil formed by a strip of a carrier material of a component used in electronics or electrical engineering, wherein the strip has a surface formed by rolling a base material. The strip has at least one exposed contact point for a wire, which is electrically connected to the contact point by wire bonding. At the contact point, the surface formed by rolling is removed by scraping.The base material of the coil is exposed at the contact point.

[0020] Each of the contact points typically has a width of between 2 and 10 mm.

[0021] To produce the coil according to the invention, a process is used in which a strip is first produced by rolling a base material. Material of the carrier material is locally removed from the surface of the strip formed by rolling in order to form the exposed contact point on the strip, preferably in the manner described above. The strip material is then wound to form a coil.

[0022] Prepared in this way, the strip material is either subjected to electroplating by the carrier material manufacturer, as required, or it is sent to a puncher, which unwinds the strip from the coil on site and punches, for example, system carriers for semiconductors, either as cut-to-length sections or wound punched strip. These and subsequent processes are then comparable to those for materials for which no surface removal occurs in the wire bonding area and are state of the art. Further details and advantages of the present invention will become apparent from the following description of exemplary embodiments of the invention in conjunction with the drawings. In these drawings:

[0023] Figure 1 is a perspective cross-sectional view of a length of tape;

[0024] Figure 2 is a perspective view of a coil with the end of the strip forming this coil;

[0025] Figure 3 is a side view of a bonded circuit breaker using the tape of Figure 1,

[0026] Figure 4 is a plan view of Figure 4 and

[0027] Figure 5 is a perspective view of a unit ready for shipment.

[0028] Figure 1 shows an exemplary embodiment of a substrate material, specifically CuSn6 R500. This exemplary embodiment illustrates a sectional view through a length 2 of a strip 4 transverse to the rolling direction, indicated by the arrows at reference symbol W. The strip 4 has a thickness S of approximately 0.8-0.02 mm and a width B of 30-0.02 mm.

[0029] Reference numeral 6 designates two contact points near the edge of the strip 4, which are formed by machining the surface 8 created by rolling. In the application example, the distance A between this contact point 6 and each edge of the length 2 is 10 mm. The length L and the distance A are each removed transversely to the rolling direction. As a result of this machining, the contact point 6 is formed in the vertical direction below the surface 8 in a base material BA of the strip, with which the strip was produced from the melt and brought to the desired thickness S by rolling. Reference numeral M in Figure 1 indicates a region of the rolled strip 4 close to the surface, which region may have been undesirably modified by the rolling process for the electrical connection by means of wire bonding.

[0030] The contact point 6 is framed at the transition to the surface 8 at an angle of 45° and has a width b of 5 mm. As the reduced thickness R illustrates, the strip 4 is only 0.77 mm + / - 0.012 mm thick at the contact point 6. This reduced thickness of the strip 4 results from machining the surface 8 of the strip 4. The reduced thickness R is selected such that the modified surface area M is reliably removed by material removal and the strip 4 with its base material B is exposed within the contact point 6, so that the predetermined material properties of the strip are present there.

[0031] In the illustrated embodiment, contact point 6 was created by a peeling process. This resulted in a surface roughness in the rolling direction of Ra=0.018 pm and Rmax=0.705 pm at contact point 6. The roughness in the transverse direction, ie, perpendicular to the longitudinal direction, was Ra=0.173 pm and Rmax=1.228 pm.

[0032] Figure 2 shows an example of a coil 10 formed from a strip 2 modified from Figure 1. As the illustration of the free end of the strip 2 in Figure 2 conveys, this strip 4 has only a single contact point 6 compared to the embodiment according to Figure 1. For details of this contact point 6, reference can be made to the previous description of Figure 1.

[0033] Figures 3 and 4 illustrate the attachment and connection of a semiconductor switch 12 to the strip 4 shown in Figure 1. The strip 4 is divided into several segments 14 by punching, of which segments 14.1 form busbars for the power current switched by the semiconductor switch 12. These segments 14.1 are each formed by punching the edges of the strip 4. The semiconductor switch 12 is electrically connected to one of the segments 14.1 via its wire bridges / pins 16.

[0034] Segment 14.2 was punched from the center of strip 4. In the illustrated embodiment, it carries the power switch 12 and serves as a busbar for the polarity to be switched by the semiconductor switch 12.

[0035] The extension of segment 14.2 in the rolling direction corresponds to the sum of the extensions of segments 14.1 in the rolling direction on one side of segment 14.2.

[0036] Figure 5 illustrates an embodiment of a ready-to-ship unit 18 comprising the coil 10, a pallet 20 and securing straps 22.

[0037] In the facility that provides the strip 4 with the contact point 6, the strip 4 is wound into a coil 10 after the contact point 6 has been formed, placed on the pallet 20, and secured for transport using the securing straps 22. Prepared in this manner, the ready-to-ship unit 18 is shipped to the facility that performs the bonding.

[0038] List of reference symbols

[0039] 2 length pieces

[0040] 4 volumes

[0041] 6 Contact point

[0042] 8 Surface

[0043] 10 coils

[0044] 12 semiconductor switches

[0045] 14.1 Segment

[0046] 14.2 middle segment

[0047] 16 wire bridges / pins

[0048] 18 units ready for dispatch

[0049] 20 pallets

[0050] 22 security tape

[0051] A distance

[0052] B Width of the band b Width of the contact point

[0053] R reduced thickness

[0054] S Strength

Claims

Claims 1. A method for producing an electronic component with at least one electronic component (12) which is electrically connected by wire bonding to a segment (14.1) of a strip (4) made of a carrier material, wherein the strip (4) is rolled by rolling a base material, the surface (8) formed by rolling is removed to form a contact point (6) exposed on the strip (4) which is formed by the base material, the rolled strip (4) is wound up into a coil (10), the rolled strip (4) is unwound from the coil (10) and the segment (14.1) is separated from the strip (4), and a wire (16) is bonded in an electrically conductive manner in the contact point (6) for the electrical connection of the electronic component (12).

2. Method according to claim 1, characterized in that the contact point (6) is produced continuously in the rolling direction (W) by removing surface material of the carrier material.

3. Method according to claim 1 or 2, characterized in that a carrier segment (14.2) is separated from the band (4) and that the electronic component (12) is mounted on the carrier segment (14.2).

4. Method according to one of the preceding claims, characterized in that the surface (8) formed by rolling is removed in such a way that the contact point (6) is delimited on at least two sides by the surface (8) formed by rolling.

5. Method according to one of the preceding claims, characterized in that the surface (8) formed by rolling is removed by scraping.

6. A unit (18) ready for dispatch, comprising a coil (10) formed by a strip (4) of a carrier material of a component used in electronics or electrical engineering, the strip (4) having a surface (8) formed by rolling a base material, and a transport pallet on which the coil (10) rests and to which the coil (10) is connected in a transport-secure manner, characterised by a contact point (6) exposed on the strip (4) for a wire (16) which is electrically connected to the contact point (6) by wire bonding, the surface (8) formed by rolling being removed at the contact point (6) and the base material of the coil (10) being exposed.

7. Ready-to-ship unit (18) according to claim 6, characterized in that the base material is a copper alloy.

8. Ready-to-ship unit (18) according to claim 6 or 7, characterized in that the band (4) complies with the specification according to DIN ISO 1758.

9. Ready-to-ship unit (18) according to one of claims 6 to 8, characterized in that at the contact point (6) the surface (8) formed by rolling is removed from the surface (8) formed by rolling up to a distance (A) of between 30 pm and 150 pm.

10. Ready-to-ship unit (18) according to one of claims 6 to 9, characterized in that at the contact point (6) a material forming the surface (8) formed by rolling is removed by machining.

11. Ready-to-ship unit (18) according to claim 10, characterized in that the material forming the surface (8) is removed by scraping.

12. Ready-to-ship unit (18) according to one of claims 6 to 11, characterized in that the contact point (6) has a width (b) between 2 and 10 mm.

13. Ready-to-ship unit (18) according to one of claims 6 to 12, characterized in that the contact point (6) is delimited at least on one side by the surface (8) formed by rollers.

14. Electronic component with at least one electronic component (12) which is electrically connected by wire bonding to a segment (14.1) of a strip (4) made of a carrier material, wherein the segment (14.1) has a surface (8) formed by rolling a base material and an exposed contact point (6) at which the surface (8) formed by rolling is removed, which surface is formed by the base material of the coil and to which a wire electrically connecting the electronic component (12) to the segment (14.1) is bonded.

15. Electronic component according to claim 14, characterized by a carrier segment (14.2) formed from the strip (4) on which the electronic component (12) is mounted.

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