Head unit for a bump coining machine.

Abstract

This invention provides a head unit for a bump coining machine that offers improved clamping strength, high surface hardness, and excellent release properties. [Solution] The bump coining device head unit 100 for coining the bump 15 includes a coining body that is vertically movable relative to the bump, and a coining head 120 positioned at the end of the coining body so as to face the upper surface of the bump, and made of a material having a single-crystal structure containing different elements. As a result, the bump coating device head unit can have improved bonding strength, high surface hardness, and excellent release properties.

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a head unit for a bump coining apparatus. An embodiment of the present invention relates to a head unit that constitutes a bump coining apparatus capable of flattening bumps formed on a circuit board by pressing them. [Background technology]

[0002] In the case of computers, laptops, and mobile phones, as storage capacity increases, research is being conducted on increasing the capacity of chips, such as large-capacity random access memory (RAM) and flash memory, while simultaneously miniaturizing the packages.

[0003] To achieve this, research is focused on naturally miniaturizing the size of packages used as core components, and various techniques are being proposed and studied for mounting a larger number of packages on a limited-sized substrate.

[0004] As a method to reduce the size of such packages, a technology has been proposed that can minimize the size and thickness of the package while using chips with the same memory capacity; this is commonly known as a flip-chip package.

[0005] A printed circuit board contained in a flip-chip package includes bumps as terminals for connecting to components such as semiconductor chips or motherboards (e.g., flip-chip connections).

[0006] To form the bumps, various methods are employed, such as applying conductive paste to the top surface of the pad using screen printing, dispensing, or inkjet methods, followed by a reflow process, or attaching small solder balls.

[0007] If the surface of a bump is formed in a spherical or hemispherical shape, contact failures may occur during semiconductor chip and device mounting. Therefore, a bump coining device is used for the coining process to flatten the bump.

[0008] However, in the coining process in which a head unit included in a bump coining apparatus pressurizes the bumps, the head unit may be made of a metal material. In this case, if pinholes remain on the surface of the head unit, a problem may arise in which the uniformity of the flat surface of the bump is weakened. To remove the pinholes, a separate chrome plating layer may be formed on the surface of the head unit. However, the chrome plating layer needs to be formed with a relatively large thickness, for example, 50 μm or more, and there is a problem that defects are likely to occur in the plating process in which the chrome plating layer is formed.

[0009] In contrast, the metal constituting the head unit has relatively low surface hardness and a high coefficient of friction, which can cause scratches on the surface of the head unit. Therefore, a separate diamond-like coating (DLC) layer may be required on the lower surface of the head unit. In this case, the coating layer may peel off from the head unit.

[0010] As described above, when the head unit included in the bump coining apparatus is made of metal, an additional chrome plating layer or DLC coating layer is required through a chrome plating process or a coating process. There is a problem in that a large number of defects occur in the additionally required chrome plating or coating process. [Overview of the Initiative] [Problems that the invention aims to solve]

[0011] An embodiment of the present invention provides a head unit for a bump coining machine that has improved clamping strength and high surface hardness while simultaneously ensuring excellent release properties. [Means for solving the problem]

[0012] A head unit for a coining device for coining bumps according to one embodiment of the present invention includes a coining body that is vertically movable relative to the bump, and a coining head that is positioned at the end of the coining body so as to face the upper surface of the bump and is made of a material having a single-crystal structure in which different elements are bonded.

[0013] In one embodiment of the present invention, the coining head has a unit area (1 cm²). 2 ) has a pinhole density of 2 or less per unit, where a pinhole can be defined as having a diameter in the range of 0.1 μm to 2 μm.

[0014] In one embodiment of the present invention, the coining head may have a compressive strength in the range of 2 to 5 GPa. In one embodiment of the present invention, the coining head may have a surface roughness (Ra) of 0.02 μm or less.

[0015] In one embodiment of the present invention, the coining head is 40 to 500 W·m -1 ·K -1 It may have a thermal conductivity within this range. In one embodiment of the present invention, the coining head is 2.5 × 10 -6 ~10.0×10 -6 ℃ -1 It may have a thermal expansion coefficient within the range of [this range].

[0016] In one embodiment of the present invention, the coining head may include one selected from the group of single-crystal materials consisting of silicon carbide (SiC), sapphire (Al2O3), and zirconia (ZrO2). Here, the coining head formed of the single-crystal silicon carbide material can be formed through a sublimation growth method or a chemical vapor deposition method.

[0017] In an embodiment of the present invention, the coining head may further include a heat-resistant lubricating layer in contact with the top surface of the bump. In an embodiment of the present invention, the coining head may be detachably provided to the coining body.

Effects of the Invention

[0018] According to an embodiment of the present invention, the head unit is disposed at an end of the coining body to face the top surface of the bump, and includes the coining head formed of a substance having a single-crystal structure material containing a different element, whereby improved compression bonding strength, high surface hardness, and at the same time excellent releasability can be ensured.

[0019] Furthermore, by providing the coining head detachably from the head body, the coining head can be easily replaced when damage occurs on the surface thereof.

Brief Description of Drawings

[0020] [Figure 1] It is a perspective view for explaining a head unit for a bump coining device according to an embodiment of the present invention. [Figure 2] It is a configuration diagram for explaining the head unit of FIG. 1. [Figure 3] It is a perspective view showing bumps before and after performing a coining process.

Mode for Carrying Out the Invention

[0021] Embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, the present invention is not to be limited to the embodiments described below, and can be embodied in a variety of other forms. The following embodiments are provided not so much to fully complete the present invention, but rather to adequately convey the scope of the present invention to those skilled in the art in the field of the present invention.

[0022] In embodiments of the present invention, when one element is described as being positioned on or connected to another element, it is possible that the element may be directly positioned on or connected to the other element, and other elements may be interposed between them. In contrast, when one element is described as being directly positioned on or connected to another element, there are no other elements between them. Terms such as first, second, third, etc. can be used to describe a variety of items such as various elements, compositions, regions, layers and / or parts, but the items described above are not limited by these terms.

[0023] The technical terms used in the embodiments of the present invention are used solely for the purpose of describing specific embodiments and are not intended to limit the invention. Furthermore, unless specifically limited, all terms, including technical and scientific terms, have the same meaning as those understood by those skilled in the art who have ordinary skill in the field of the present invention. The same terms as those limited in a standard dictionary are to be interpreted as having a meaning consistent with that in the context of the relevant technology and the description of the present invention, and are not to be interpreted ideally or overly introspectively unless explicitly limited.

[0024] Embodiments of the present invention will be described with reference to schematic illustrations of ideal embodiments of the present invention. Therefore, variations from the illustrated shapes, such as changes in the manufacturing method and / or tolerances, are well foreseeable. Accordingly, embodiments of the present invention will not be described as being limited to specific shapes of the illustrated regions, and will include deviations in shape. The elements shown in the drawings are entirely schematic, and these shapes are not intended to describe the exact shapes of the elements, nor do they limit the scope of the present invention.

[0025] Figure 1 is a perspective view illustrating a head unit for a bump coining apparatus according to one embodiment of the present invention, and Figure 2 is a configuration diagram illustrating the head unit of Figure 1. Referring to Figures 1 and 2, the head unit (100) of the bump coining device that coins the bumps (13) of the printed circuit board (10) includes a head body (110) and a coining head (120). The bumps (11) formed on the substrate have their spherical surfaces flattened by a coining process using the bump coining device.

[0026] The head body (110) can be driven in the vertical direction. A press unit that applies pressure to the head body is connected to the head body (110). A separate leveling unit may be connected to the head body. This allows the coining head connected to the head body to be leveled relative to the upper surface of the substrate. Furthermore, a heating element such as a heater may be provided inside the head body.

[0027] The coining head (120) descends and pressurizes the bump (13), thereby flattening the upper surface of the bump. The bottom surface of the coining head (120) facing the bump (13) can be formed flat.

[0028] The coining head (120) can be formed in a single plate shape and can cover a number of bumps (13) at once, thereby pressing multiple bumps (13) simultaneously. As the coining body moves up and down, the coining head (120) can move up and down. When the printed circuit board (10) is placed below the head body (110), the head body (110) moves downward toward the bump (13), causing the coining head to pressurize the bump (13) at a high temperature.

[0029] Once the coining head (120) is pressurized, the head body (110) can rise to the top again. When the bump coining apparatus, including the head unit (100), completes the coining process, a bump (15) with a flat top surface can be formed on the substrate.

[0030] The coining head can be formed from a material having a single-crystal structure containing dissimilar elements, instead of conventional metal materials. For example, the coining head can be formed from one selected from the group of single-crystal materials consisting of silicon carbide (SiC), sapphire (Al2O3), and zirconia (ZrO2). Therefore, an additional chromium plating layer or DLC coating layer can be omitted from the coining head. As a result, defects that may occur in the manufacturing process for producing the coining head can be drastically reduced.

[0031] That is, if the coining head is formed from a material having a single-crystal structure containing different elements instead of a conventional metal material, the coining head has a unit area (1 cm²). 2 The pinhole density is 2 or less per surface, where a pinhole is defined as having a diameter in the range of 0.1 μm to 2 μm. Therefore, by reducing the pinhole density remaining on the surface of the coining head, the bump coining apparatus including the coining head can perform an improved coining process.

[0032] Furthermore, the coining head may have a compressive strength in the range of 2 to 5 GPa. This ensures improved durability for the bump coining apparatus, including the coining head.

[0033] In one embodiment of the present invention, the coining head may have a surface roughness (Ra) of 0.02 μm or less. On the other hand, when the coining head is formed of, for example, a silicon carbide (SiC) material having a single crystal structure, it may have a friction coefficient of 0.5 or less. Accordingly, after the bump coining apparatus performs the bump coining process, residual bump material on the coining head can be reduced due to the excellent lubricity of the coining head. Therefore, the bump coining apparatus can ensure improved release properties.

[0034] The coining head formed of the silicon carbide single crystal material may be formed through a sublimation growth method or a chemical vapor deposition method. The sublimation growth method is a method of sublimating SiC powder at a high temperature, and then recrystallizing the vapor on a cooled substrate to form a single crystal. For this purpose, SiC powder can be sublimated at a high temperature of about 2000°C or higher, and then deposited on a lower temperature substrate (with a seed film formed thereon) to grow the single crystal. The sublimation growth method can produce SiC single crystals with relatively high quality.

[0035] The chemical vapor deposition (CVD) method is a method of decomposing a gaseous compound to deposit a solid on a substrate. More specifically, a silicon source (e.g., SiH4, SiCl4) and a carbon source (e.g., C3H8, CH4) are injected into a reaction chamber to cause a chemical reaction at a high temperature, thereby depositing SiC on the substrate. The chemical vapor deposition method can grow highly pure SiC single crystals.

[0036] In one embodiment of the present invention, the coining head has a thermal conductivity of 40 to 500 W·m -1 ·K -1It may have a thermal conductivity within a certain range. The coining head formed of the single-crystal material can more effectively transfer the heat generated by the heating element provided in the head body to the bump. This ensures improved coining efficiency and characteristics for the bump coining apparatus.

[0037] In one embodiment of the present invention, the coining head is 2.5 × 10 -6 ~10.0×10 -6 ℃ -1 It may have a thermal expansion coefficient within this range. Because the coining head expands relatively little with respect to heat, the coining head can be made to have excellent durability.

[0038] In particular, the coining head can be formed from a single-crystal material consisting of silicon carbide (SiC), sapphire (Al2O3), or zirconia (ZrO2). When the coining head is formed from a single crystal material of silicon carbide (SiC), it may have a cubic-zinc blend structure or a hexagonal-wurtzite crystal structure. When the coining head is formed from a single crystal material of sapphire (Al2O3), it may have a hexagonal crystal structure.

[0039] On the other hand, the coining head can be formed from zirconia (ZrO2) having a cubic crystal structure. In one embodiment of the present invention, the coining head may further include a heat-resistant lubricating layer that contacts the upper surface of the bump. If the coining head has hydrophobic and lipophilic properties, the heat-resistant lubricating layer can be easily applied to the coining head. Furthermore, the heat-resistant lubricating layer can additionally improve the release properties from the surface of the bump.

[0040] Examples of materials constituting the heat-resistant lubricating layer may include polyether-ether ketone (PEEK). Referring to Figure 2, the coining head may be detachably mounted to the coining body.

[0041] Various methods can be used to fasten the coining head to the head body, such as a sliding method, a hook fastening method, or a bolt / nut fastening method. This allows the coining head to be easily separated from the head body and replaced if it is damaged due to wear or corrosion on its surface.

[0042] While the above description has been made with reference to preferred embodiments of the present invention, those skilled in the art will understand that the present invention can be modified and altered in various ways without departing from the spirit and scope of the invention as described in the following claims.

[0043] Many other embodiments besides those described above are included within the scope of the claims of the present invention. [Explanation of symbols]

[0044] 100: Head unit for bump coining machine 110: Head body 120: Coining Head

Claims

1. In a head unit for a bump coining device that coins bumps, A coining body provided to be vertically movable relative to the aforementioned bump; and A head unit for a bump coining apparatus, comprising a coining head positioned at the end of the coining body so as to face the upper surface of the bump, and formed of a material having a single-crystal structure containing different elements;

2. The coining head has a unit area (1 cm²) 2 The head unit for a bump coining apparatus according to claim 1, characterized in that it has a pinhole density of 2 or less per unit, where a pinhole is defined as having a diameter in the range of 0.1 μm to 2 μm.

3. The head unit for a bump coining apparatus according to claim 1, characterized in that the coining head has a compressive strength in the range of 2 to 5 GPa.

4. The head unit for a bump coining apparatus according to claim 1, characterized in that the coining head has a surface roughness (Ra) of 0.02 μm or less.

5. The coining head has a power output of 40 to 500 W·m -1 ・K -1 A head unit for a bump coining apparatus according to claim 1, characterized by having a thermal conductivity within the range of [value].

6. The coining head is 2.5 × 10 -6 ~10.0 x 10 -6 K -1 The head unit for a bump coining apparatus according to claim 1, characterized in that it has a thermal expansion coefficient in the range of [range].

7. The coining head is formed of one material selected from the group of single crystal materials consisting of silicon carbide (SiC), sapphire (Al 2 O 3 ) and zirconia (ZrO 2 ), characterized in that the head unit for a bump coining device according to claim 1.

8. The head unit for a bump coining apparatus according to claim 7, characterized in that the coining head formed of the silicon carbide single crystal material is formed by sublimation growth or chemical vapor deposition.

9. The head unit for a bump coining apparatus according to claim 1, characterized in that the coining head further includes a heat-resistant lubricating layer that contacts the upper surface of the bump.

10. The head unit for a bump coining apparatus according to claim 1, characterized in that the coining head is detachably provided with respect to the coining body.

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