Semiconductor package comprising fastening means for fastening
By designing a claw-structured fastening device, the high cost and time-consuming process of fixing semiconductor packages and heat sinks in existing technologies are solved, achieving low-cost, fast, and reliable fastening and improving heat dissipation efficiency.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- INFINEON TECHNOLOGIES AG
- Filing Date
- 2025-10-10
- Publication Date
- 2026-04-17
AI Technical Summary
In the existing technology, the method of fixing semiconductor packages and heat sinks requires specially designed heat sinks and PCBs, which results in high costs and time-consuming fixing processes. In addition, the difficulty in fixing screws at the same time may cause the module to tilt.
The fastening device consists of an upper and a lower part. The lower part is designed as a claw structure, which hooks into the inner wall of the heat sink hole through an elastic area and ensures that the lower surface of the package is in close contact with the heat sink through elastic restoring force, simplifying the fixing process.
It achieves low-cost, fast, and reliable semiconductor packaging and heat sink fixing, avoids module tilting, and improves fixing efficiency and heat dissipation effect.
Smart Images
Figure CN121888959A_ABST
Abstract
Description
Technical Field
[0001] This disclosure relates to a semiconductor package including a fastening device for fastening a semiconductor package to a heat sink. Background Technology
[0002] A known semiconductor package includes a semiconductor die at least partially surrounded by a housing. A printed circuit board (PCB) can be mounted on the semiconductor package, and the semiconductor package can include an outwardly extending fastening portion beneath the PCB. To attach the semiconductor package to a heat sink, the heat sink can include threaded holes. Screws can be inserted through the fastening portion and the threaded holes to secure the lower surface of the package to the heat sink. Through-holes are also required on the PCB to allow the screws to be secured in the threaded holes using appropriate tools (e.g., a screwdriver).
[0003] From the customer's perspective, the heatsink and PCB must have different design features to enable reliable screw fastening during production. The heatsink requires at least two threaded holes per power module, and the PCB must have through holes corresponding to each screw location to secure the screws during assembly. Implementing these design features is not only costly but also presents numerous drawbacks for a variety of reasons. Special heatsink designs are required, including two threads with a minimum depth. Screw fastening is not mechanically optimal, and the difficulty in simultaneously fastening screws can lead to module tilting. Furthermore, the sequential order of screw fastening is time-consuming.
[0004] This disclosure is necessary for these and other reasons. Summary of the Invention
[0005] One aspect of this disclosure relates to a semiconductor package including a semiconductor transistor die, a housing at least partially surrounding the semiconductor transistor die, and at least two fastening means for fastening the semiconductor package to a heat sink, each of the fastening means including an upper portion and a lower portion, the upper portion being secured to the housing and including a resilient region, and the lower portion being connected to the resilient region.
[0006] According to embodiments of semiconductor packaging, the lower portion is designed to function as a claw, i.e., by forming the outer end of the lower portion, it is able to hook onto the inner wall of a hole in a heat sink. For example, the lower portion may include a vertical shaft and a spring, the spring being attached to the vertical shaft at its outer end, wherein the spring is bent upwards such that during insertion into the hole in the heat sink, the spring is able to hook its outer end onto the inner wall of the hole. The vertical shaft and the spring may be made of stainless steel.
[0007] According to another example, the outer end of the lower portion may include a vertical shaft in the form of an expansion pin. The lateral protrusions of the pin can also hook onto the inner wall of the hole.
[0008] In addition to the above, the elastic region of the upper portion provides a restoring force when the lower portion is inserted into the hole of the heat sink. At the end of the insertion process, this restoring force exerts an upward force on the lower portion, causing the outer lower part of the lower portion to wedge into the inner wall of the hole. This restoring force also presses the lower thermally conductive surface of the package into contact with the heat sink, thereby facilitating heat transfer from the package to the heat sink.
[0009] According to an embodiment of a semiconductor package, two fastening devices are embedded in two opposing sidewalls of the housing.
[0010] Therefore, this disclosure describes a metal component molded into the housing of a power module, which provides a resilient structure for downward pressure. The fastening device provides sharp metal claws that can be secured into a blind metal hole by a linear press-in motion only.
[0011] According to an embodiment of the semiconductor package, the semiconductor package is further configured to have a printed circuit board connected thereto. As an example, the printed circuit board includes two through-holes configured to be positioned directly above the central sections of the horizontal and vertical portions of the fastening device when the printed circuit board is mounted to the housing.
[0012] According to an embodiment of a semiconductor package, the semiconductor package further includes a substrate to which a semiconductor transistor die is attached, wherein the substrate may be one or more of direct copper bonding, direct aluminum bonding, aluminum brazing, or an insulating metal substrate.
[0013] Semiconductor packages may also include a thermally conductive lower layer for effectively transferring heat from the package to a heat sink. This layer may be in the form of a metal layer, particularly made of copper, covering the bottommost main surface of the semiconductor package, and this metal layer may form part of the substrate. Attached Figure Description
[0014] The accompanying drawings are included to provide a further understanding of the embodiments, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments and, together with the description, serve to explain the principles of the embodiments. Other embodiments and many anticipated advantages of the embodiments will be readily understood by referring to the following detailed description.
[0015] The elements in the accompanying drawings are not necessarily proportional to each other. The same reference numerals denote corresponding similar parts.
[0016] Figure 1A and Figure 1B A cross-sectional side view (A) and a top view (B) of the semiconductor package of this disclosure are shown.
[0017] Figures 2A to 2CA cross-sectional view is shown illustrating the process of inserting a semiconductor package into a hole in a heat sink.
[0018] Figure 3 A cross-sectional representation of another example of the vertical portion of the fastening device is shown. Detailed Implementation
[0019] In the following detailed description, reference is made to the accompanying drawings, which form a part of this document, and specific embodiments in which the present disclosure may be practiced are illustrated by way of illustration. In this regard, directional terms such as “top,” “bottom,” “front,” and “rear” are used with reference to the orientation of the described drawings. Because components of the embodiments can be placed in a number of different orientations, the directional terms are used for illustrative purposes and are by no means limiting. It should be understood that other embodiments may be utilized and structural or logical changes may be made without departing from the scope of the present disclosure. Therefore, the following detailed description should not be considered limiting, and the scope of the present disclosure is defined by the appended claims.
[0020] It should be understood that, unless otherwise expressly stated, features of the various exemplary embodiments described herein may be combined with each other.
[0021] As used herein, the terms “joining,” “attachment,” “connection,” “coupling,” and / or “electrical connection / electrical coupling” do not imply that elements or layers must be in direct contact with each other; intermediate elements or intermediate layers may be provided between elements that are “joined,” “attached,” “connected,” “coupled,” and / or “electrically connected / electrically coupled.” However, according to this disclosure, the above terms may also optionally have the specific meaning of elements or layers being in direct contact with each other, i.e., no intermediate elements or intermediate layers are provided between elements that are “joined,” “attached,” “connected,” “coupled,” and / or “electrically connected / electrically coupled.”
[0022] Furthermore, the term "above" used herein to refer to a layer of parts, elements, or materials formed or placed "above" a surface may be used to indicate that the part, element, or material layer is "indirectly" located (e.g., placed, formed, deposited, etc.) on the implied surface, wherein one or more additional parts, elements, or layers are arranged between the implied surface and the part, element, or material layer. However, the term "above" used herein to refer to a layer of parts, elements, or materials formed or placed "above" a surface may also optionally have a specific meaning, namely, that the part, element, or material layer is "directly" located (e.g., placed, formed, deposited, etc.) on the implied surface (e.g., in direct contact).
[0023] Furthermore, the word "exemplary" is used herein to mean as an example, instance, or illustration. Any aspect or design described herein as "exemplary" is not necessarily to be construed as superior to other aspects or designs. Rather, the use of the word "exemplary" is intended to present concepts in a concrete manner. As used in this application, the term "or" is intended to mean an inclusive "or" rather than an exclusive "or." That is, unless otherwise stated or clearly indicated by the context, "X adopts A or B" is intended to mean any natural inclusive permutation and combination. That is, "X adopts A or B" holds true if X adopts A; X adopts B; or X adopts both A and B. Furthermore, the article "a" used in this application and the appended claims can generally be interpreted as meaning "one or more," unless otherwise stated or clearly indicated from the context to be a singular form. In addition, at least one of A and B generally means A or B or both A and B. Detailed description
[0024] Examples of semiconductor packaging can use various types of transistor devices. These examples can also use horizontal or vertical transistor devices, wherein the structures can be configured such that all contact elements of the transistor device are disposed on one main surface of the semiconductor die (horizontal transistor structure), or in a configuration where at least one electrical contact element is disposed on a first main surface of the semiconductor die, and at least one other electrical contact element is disposed on a second main surface opposite to the main surface of the semiconductor die (vertical transistor structure), such as a MOS transistor structure or an IGBT (Insulated Gate Bipolar Transistor) structure.
[0025] According to embodiments of semiconductor packaging, a semiconductor transistor die is a semiconductor power transistor die. Here, the term "power semiconductor transistor die" can refer to a semiconductor transistor die that provides at least one of high voltage blocking capability or high current carrying capability. A power semiconductor die can be configured for high currents with a maximum current value of several amperes, such as 10A, 250A, 600A, 1000A, or up to or even exceeding 1000A. Similarly, the voltage associated with such current values can have values ranging from several volts to tens, hundreds, or even thousands of volts.
[0026] Examples of semiconductor packaging may include a housing that at least partially encapsulates a semiconductor die. The housing may take the form of a vertical wall surrounding the die and an optional cap on top of the encapsulating housing. Optionally, the housing may take the form of an encapsulating agent or encapsulating material in which a semiconductor transistor die and a semiconductor driver die are embedded. The encapsulating material may be any electrically insulating material, such as any kind of molding material, any kind of resin material, or any kind of epoxy resin material. The encapsulating material may also be a polymer material, a polyimide material, a thermoplastic material, a silicone material, a ceramic material, and a glass material. The encapsulating material may also include any of the above materials and may also include an embedded filler material, such as a thermal conductivity enhancer (e.g., thermally conductive particles made of AlO, BNi, AlNi, SiN, diamond, or any other thermally conductive particles).
[0027] Figure 1A and Figure 1B A cross-sectional side view (A) and a top view (B) of the semiconductor package of this disclosure are shown.
[0028] Figure 1A and Figure 1B The semiconductor package 10 shown includes: a semiconductor transistor die (not shown), particularly a semiconductor power transistor die; and a housing 11 that at least partially encapsulates the semiconductor transistor die. The semiconductor package 10 can, in principle, be of any type. Specifically, it may include a substrate (not shown), such as one or more of direct copper bonding (DCB), direct aluminum bonding, aluminum metal brazing (AMB), or insulated metal substrate (IMS). The substrate is located in or at the bottom of the housing 11. When the housing 11 takes the form of walls and optionally a cover, the substrate is attached to the lower edge of the housing wall. When the housing 11 takes the form of an encapsulant, the substrate is typically embedded in the lower surface of the encapsulant. The DCB typically includes a central ceramic layer and two copper layers disposed on the upper and lower main surfaces of the ceramic layer. The semiconductor transistor die may, for example, be disposed on the upper copper layer of the DCB.
[0029] The semiconductor package 10 may also include a thermally conductive layer 14 to effectively transfer heat from the package 10 to the heat sink 15. The thermally conductive layer may be made of copper, disposed on the bottom surface of the housing 11, and in a secured state in close contact with the heat sink 15. The thermally conductive layer 14 may also form the lower copper layer of the substrate. However, it is also conceivable that this layer may be formed of a non-metallic material, such as a thermally conductive but electrically insulating thermal interface material (TIM).
[0030] The printed circuit board (PCB) 13 can be secured to electrical terminals 16 extending upward from the semiconductor package 10. The PCB 13 may include circuitry connected to a semiconductor transistor die via package terminals, the circuitry including, for example, a semiconductor driver die for controlling the semiconductor transistor die, and possible passive devices such as resistors, capacitors, etc.
[0031] The semiconductor package 10 will be mounted on the heat sink 15, particularly on the customer side. For this purpose, the semiconductor package 10 includes at least two fastening devices 12, only one of which is shown here. The two fastening devices 12 can be embedded in two opposing sidewalls of the housing 11.
[0032] Each of the fastening devices 12 includes an upper horizontal retaining portion 12A that is secured to the housing 11. In the embodiment shown here, this securing is accomplished by inserting the right end of the horizontal retaining portion 12A into the housing 11. Each of the fastening devices 12 also includes a lower vertical portion 12B connected to the horizontal retaining portion 12A.
[0033] In such Figure 1A and Figure 1B In the embodiment of the semiconductor package 10 shown, the vertical portion 12B of the fastening device 12 includes a vertical shaft 12B.1 and a spring 12B.2. The spring 12B.2 is attached to the vertical shaft 12B.1 at its outer end. The spring 12B.2 is attached to the surface of the vertical shaft 12B.1 and then bent upwards, such that its outer end can hook onto the inner wall of the hole 15A of the heat sink 15. The spring 12B.2 and the shaft 12B.1 together form a wedge-shaped structure, which facilitates the insertion of the vertical portion 12B into the hole 15A of the heat sink 15.
[0034] The printed circuit board 13 includes two through holes 13A, which are positioned directly above the center sections of the horizontal portion 12A and the vertical portion 12B of the fastening device 12 when the PCB 13 is secured to the semiconductor package 10. The through holes 13A are used to insert pins to press the fastening device 12 downward.
[0035] The horizontal portion 12A of the fastening device 12 may also include a central portion 12A.1 and a resilient region 12A.2. The resilient region 12A.2 may take the form of two portions located on either side of the central portion 12A.1. The resilient region 12A.2 applies a restoring force at the end of the process of inserting the vertical portion into the hole 15A of the heat sink 15.
[0036] Figures 2A to 2C A cross-sectional view is shown illustrating the process of inserting a semiconductor package into a hole in a heat sink.
[0037] Figure 2AThe diagram shows the state before the vertical sections 12B of the two fasteners 12 are inserted into the holes 15A in the heat sink. The fasteners 12 are aligned such that the vertical portions 12A are positioned above the holes 15A. Pins are then inserted through the through-holes 13A of the PCB 13, and pressed downwards by applying downward pressure. Pins are then used to press down the center region 12A.1 of the horizontal portion 12, and thus press the vertical portion 12B downwards into the holes 15A of the heat sink 15. These pins can form a single tool for simultaneously pressing down both fasteners 12.
[0038] Figure 2B This shows an intermediate step in the process of inserting the vertical portion 12B into the hole 15A of the heat sink 15.
[0039] Figure 2C The diagram shows the state at the end of the process of inserting the vertical portion 12B into the hole 15A of the heat sink 15. Full insertion causes the horizontal spring portion 12A to bend downwards, such that portion 12A.2 tilts obliquely downwards, and the inner spring portion 12A.1 contacts and is parallel to the upper flat surface of the heat sink 15. A restoring force is then provided by the elastic portion 12A.2 of the horizontal portion 12A of the fastening device 12. This provides an upward force on the vertical section 12B, causing one end of the spring 12B.2 to wedge into the inner wall of the hole 15A of the heat sink 15. For this purpose, the spring 12B.2 is preferably sharpened at one end. The portion of the spring 12B.2 opposite this end rests on the corresponding opposing inner wall of the hole 15A. Because the vertical portion 12B locks the horizontal portion 12A in position against the heat sink 15, the elastic portion 12A.2 applies a downward force to the semiconductor package, thereby pressing the lower metal layer surface 14 into contact with the heat sink 15.
[0040] Hole 15A can be a blind via with defined diameter and tolerances, which would be the easiest and cheapest option for the customer. Furthermore, the through-hole 13A in PCB 13 can be smaller, allowing the customer to use the extra space on PCB 13 for other purposes.
[0041] Figure 3 A cross-sectional representation of another example of the vertical portion of the fastening device is shown.
[0042] like Figure 3 The lower vertical portion 22B shown may be part of a fastening device that can be connected to... Figure 1A and Figure 1B The same as shown, specifically having as Figure 1A and Figure 1B The upper retaining portion 12A is shown. Only the vertical portion differs. Figure 1A and Figure 1BThe vertical portion in Figure 2A. Figure 2C The vertical portion includes a vertical shaft 22B.1 and an outer end 22B.2, with the outer end 22B.2 in the form of an expansion pin. The outwardly protruding element at the lower part of the outer end 22B.2 also serves to wed into the inner wall of the hole 15A at the end of the process of pressing the vertical section 22B into the hole 15A. The vertical portion 22B can also be made of stainless steel.
[0043] Typically, metal claws can have different designs, but the working principle is always the same: they should be designed to be easy to insert into the hole 15A but very difficult to remove, even if possible. Although illustrated here as a single integral part, it can also be assembled from multiple sub-parts. The claw is connected to a horizontal portion 12A, which includes a resilient spring element 12A.2. During insertion, the claw is bent by the vertical inner wall of the radiator hole, while the opposite side of the claw must be supported by another inner wall. Example
[0044] Specific examples of this disclosure are described below.
[0045] Example 1 is a semiconductor package including a semiconductor transistor die, a housing at least partially enclosing the semiconductor transistor die, a lower thermally conductive flat surface, and at least two fastening means for fastening the semiconductor package to a heat sink. Each fastening means includes an upper retaining portion and a lower portion. The upper retaining portion is fixed to the housing and includes a resilient region. The lower portion is connected to the upper retaining portion and configured to be inserted into the heat sink. The resilient region is configured to secure the lower portion in the heat sink and press the lower thermally conductive flat surface against the heat sink.
[0046] Example 2 is a semiconductor package according to Example 1, wherein the outer end of the lower portion is designed such that the outer end of the lower portion can be forced by an elastic region to be fixedly engaged with the inner wall of a hole in a heat sink.
[0047] Example 3 is a semiconductor package according to Example 1 or 2, wherein the lower portion includes a vertical shaft and a spring, the spring being attached to the vertical shaft at its outer end, wherein the spring is bent upward such that its outer end can be forced by an elastic region to be fixedly engaged with the inner wall of a hole in a heat sink.
[0048] Example 4 is a semiconductor package according to Example 1, wherein the outer end of the lower portion has the form of an expansion pin.
[0049] Example 5 is a semiconductor package according to any of the preceding examples, wherein the upper portion of the fastening device is partially embedded in the housing.
[0050] Example 6 is a semiconductor package according to any of the preceding examples, wherein at least two fastening devices are secured to two opposite sidewalls of the housing.
[0051] Example 7 is a semiconductor package according to any of the preceding examples, further comprising a substrate including an upper metal layer and a lower metal layer, wherein a semiconductor transistor die is attached to the upper metal layer.
[0052] Example 8 is a semiconductor package according to Example 7, wherein the lower metal layer forms a thermally conductive flat surface.
[0053] Example 9 is a component comprising: a semiconductor package according to any of the preceding examples, and a printed circuit board connected to electrical terminals extending upward from the semiconductor package.
[0054] Example 10 is a component according to Example 9, wherein the printed circuit board includes two through holes arranged directly above the central sections of the horizontal and vertical portions of the fastener.
[0055] Example 11 is a method for mounting a component to a heat sink, the component including a printed circuit board and a semiconductor package, the package further including a semiconductor die, a housing at least partially enclosing the semiconductor die, a lower thermally conductive surface, and at least two fastening devices, each of the fastening devices further including a resilient region, the method comprising: placing the component on the heat sink such that the lower thermally conductive surface engages the heat sink, and each of the at least two fastening devices is positioned above a corresponding hole in the heat sink; pressing each of the fastening devices downward against resistance exerted by the resilient region such that a lower portion of the fastening device is inserted into the hole; and releasing the force on the fastening device such that the resilient region forces the lower portion to engage securely with the hole and forces the lower thermally conductive surface against the heat sink.
[0056] Example 12 is based on the installation method of Example 11, wherein at least two fastening devices are pressed downward simultaneously.
[0057] Example 13 is an installation method of Example 11 or 12, wherein each of at least two fastening devices is pressed down by a tool inserted through a corresponding hole in the printed circuit board.
[0058] Example 14 is an installation method according to any one of Examples 11 to 13, wherein at least two fastening devices are each pressed down by a corresponding pin of a single tool.
[0059] Furthermore, while a particular feature or aspect of an embodiment of this disclosure may be disclosed only with respect to one implementation of several embodiments, such feature or aspect may be combined with one or more other features or aspects of other embodiments if desired and advantageous for any given or particular application. Additionally, when the terms “comprising,” “having,” “with,” or variations thereof are used in the detailed description or claims, these terms are intended to indicate inclusiveness in a manner similar to “including.” Furthermore, it should be understood that embodiments of this disclosure may be implemented in the form of discrete circuits, partially integrated circuits, or fully integrated circuits or programming devices. Moreover, the word “exemplary” indicates only an example and not the best or optimal choice. It should also be understood that, for simplicity and understanding, features and / or elements described herein are represented by specific dimensions relative to each other, and actual dimensions may differ significantly from those shown herein.
[0060] Although specific embodiments have been shown and described herein, those skilled in the art will understand that various alternatives and / or equivalent implementations may be used instead of the shown and described specific embodiments without departing from the scope of this disclosure. This application is intended to cover any modifications or variations of the specific embodiments discussed herein. Therefore, this disclosure is intended to be limited only to the claims and their equivalents.
Claims
1. A semiconductor package (10), comprising: Semiconductor transistor die; A housing (11) that at least partially encloses the semiconductor transistor die; Lower thermally conductive flat surface (14); as well as At least two fastening devices (12) for securing the semiconductor package (10) to the heat sink (15), each of the fastening devices (12) comprising: An upper retaining portion (12A), said upper retaining portion (12A) being fixed to the housing (11) and including a resilient region; and The lower portion (12B) is connected to the upper retaining portion (12A) and is configured to be inserted into the heat sink (15). The elastic region is configured to fix the lower portion (12B) in the heat sink (15) and press the lower thermally conductive flat surface (14) against the heat sink (15).
2. The semiconductor package (10) according to claim 1, wherein, The outer end of the lower portion (12B) is designed such that the outer end of the lower portion (12B) can be forced by the elastic region (12A.2) to be fixedly engaged with the inner wall of the hole in the heat sink.
3. The semiconductor package (10) according to claim 1 or 2, wherein, The lower portion (12B) includes a vertical shaft and a spring attached to the vertical shaft at its outer end, wherein the spring is bent upward so that its outer end can be forced by the elastic region (12A.2) to be fixedly engaged with the inner wall of the hole (15A) of the radiator (15).
4. The semiconductor package (10) according to claim 1, wherein, The outer end of the lower portion (12B) has the form of an expansion pin.
5. The semiconductor package (10) according to any one of the preceding claims, wherein, The upper retaining portion (12A) of the fastening device (12) is partially embedded in the housing (11).
6. The semiconductor package (10) according to any one of the preceding claims, wherein, The at least two fastening devices (12) are fixed to two opposite sidewalls of the housing (11).
7. The semiconductor package (10) according to any one of the preceding claims further includes: A substrate, the substrate including an upper metal layer and a lower metal layer, wherein the semiconductor transistor die is attached to the upper metal layer.
8. The semiconductor package (10) according to claim 7, wherein, The lower metal layer forms the lower thermally conductive flat surface (14).
9. A component comprising: The semiconductor package (10) according to any one of the preceding claims, and A printed circuit board (13) is connected to an electrical terminal (16) extending upward from the semiconductor package (10).
10. The component of claim 9, wherein, The printed circuit board (13) includes two through holes (13A) arranged directly above the central sections of the horizontal portion (12A) and the vertical portion (12B) of the fastening device (12).
11. A method for mounting a component to a heat sink (15), the component including a printed circuit board (13) and a semiconductor package (10), the semiconductor package (10) including a semiconductor die, a housing (11) at least partially enclosing the semiconductor die, a lower thermally conductive surface (14), and at least two fastening devices (12), each of the fastening devices (12) including a resilient region (12A.2), the method comprising: The component is placed on the heat sink (15) such that the lower heat-conducting surface (14) engages the heat sink (15), and each of the at least two fastening devices (12) is placed above the corresponding hole (15A) in the heat sink (15). Each of the fastening devices (12) is pressed downward against the resistance exerted by the elastic region (12A.2) so that the lower portion (12B.1) of the fastening device (12) is inserted into the hole (15A); as well as Release the force on the fastening device (12) so that the elastic area (12A.2) forces the lower portion (12B.1) to be fixedly engaged with the hole (15A) and forces the lower heat-conducting surface (14) to abut against the heat sink (15).
12. The method according to claim 11, wherein, The at least two fastening devices (12) are pressed down simultaneously.
13. The method according to claim 11 or 12, wherein, Each of the at least two fastening devices (12) is pressed down by a tool inserted through the corresponding hole (13A) in the printed circuit board (13).
14. The method according to any one of claims 11-13, wherein, Each of the at least two fastening devices (12) is pressed down by the corresponding pin of a single tool.