JP2009010416A - Circuit device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a circuit device for cleaning and roughening a surface of conductive foil by irradiation with plasma, and a manufacturing method of a circuit device that solves a problem that a semiconductor element is broken etc., when contaminants sticking on a surface of a conductive material are removed using plasma. <P>SOLUTION: A separation groove 11 is formed by selectively etching the conductive foil 10 to form a conductive pattern 21. A circuit element such as a semiconductor element 22A is mounted at a desired place on the conductive pattern 21 and electrically connected to the conductive pattern 21. The conductive foil 10 is irradiated with plasma 33 from above the conductive foil to roughen a surface of the separation groove 11. Eventually, the adhesion strength between sealing resin filling the separation groove 11 and the conductive pattern 21 is improved. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a circuit device, and more particularly to a circuit device that removes residues adhered to a surface of a conductive foil by irradiating with plasma.

2. Description of the Related Art Conventionally, a circuit device set in an electronic device is required to be reduced in size, thickness, and weight in order to be used in a mobile phone, a portable computer, and the like. For example, in a semiconductor device as a circuit device, in order to satisfy such a requirement, a semiconductor device called a CSP (Chip size package) having a size equal to or slightly larger than the chip size has been developed. However, in a general CSP, a support substrate such as a glass epoxy substrate or a ceramic substrate is an essential component in order to support the entire apparatus. For this reason, since the support substrate is a thick member, there is a problem that the size of the entire semiconductor device is increased.

  In view of the above problems, a circuit device that does not require a support substrate has been developed (see, for example, Patent Document 1). A method for manufacturing the circuit device will be described below.

  Referring to FIG. 10A, a conductive foil 100 made of a metal such as copper is prepared, and a conductive pattern 100A that realizes a predetermined electric circuit is formed. As a method for forming the separation groove, a known etching process using an etching resistant mask can be used.

  Referring to FIG. 10B, a circuit element is fixed to the surface of conductive pattern 100A. As circuit elements, a chip component 103 such as a capacitor and a resistor, a semiconductor element 102, and the like are fixed. Furthermore, the electrode of the semiconductor element 102 and the conductive pattern 100A are electrically connected through a fine metal wire.

  With reference to FIG. 10C, coating with the sealing resin 105 is performed. The circuit element fixed in the previous process is covered, and the separation groove 101 of the conductive foil 100 is also filled with the sealing resin 105.

  Referring to FIG. 10D, the conductive foil 100 is etched from the back surface, and the conductive foil 100 is removed until the sealing resin 105 filled in the separation groove 101 is exposed. As a result, the conductive patterns 100A are electrically separated. Further, solder resist formation, external electrode formation, and the like are performed. Finally, each circuit device is separated by dicing the sealing resin 105 at the dot-and-dash line. In the process as described above, a circuit device that does not require a support substrate has been manufactured.

  Further, there is a plasma irradiation technique as a technique for removing contaminants attached to the surface of a pattern made of metal. With reference to FIG. 11, a method of removing contaminants attached to the surface by irradiating plasma to a lead frame on which a semiconductor device is mounted will be described.

  With reference to FIG. 11A, the structure of the lead frame 110 that has undergone a lead frame processing step, an element mounting step, and the like will be described. A semiconductor element 112 is mounted on the island 114 formed in a land shape, and a large number of leads 111 are provided so as to surround the island 114. The lead 111 corresponds to an electrode provided on the surface of the semiconductor element 112, and each electrode is electrically connected to the lead 111 through a fine metal wire 113.

With reference to FIG. 11B, a step of performing plasma irradiation will be described. First, the lead frame 110 is placed inside a sealed container. Next, a gas is introduced into the container, and plasma gas is generated by discharge. Then, radicals or ions present in the plasma gas collide with the surface of the lead frame 110, whereby the surface of the lead frame 110 is cleaned.
JP 2002-076246 A (page 7, FIG. 1)

  However, the above-described method for manufacturing a circuit device has a problem that the surface of the conductive foil 100 is contaminated due to a process until resin sealing is performed. As this contaminant, the organic residue contained in the etchant used in the step of forming the separation groove 101, dust in the air, and the like can be considered. Furthermore, if the sealing resin 105 is sealed while the contaminants as described above are attached to the surface of the conductive foil 100, the adhesion between the sealing resin 105 and the conductive foil 100 may be reduced. .

  Further, in the lead frame cleaning method by plasma irradiation as shown in FIG. 11, since the island 114 and the lead 111 are processed into a complicated shape, the lead frame 110 is locally exposed to the plasma irradiation. An increase in potential occurs. For this reason, there is a problem that a current flows into the semiconductor element 112 through the fine metal wire 113 due to a local potential difference of the lead frame, and an element such as a CMOS formed on the surface of the semiconductor element is destroyed. Further, since the lead frame 110 becomes high temperature in the plasma irradiation process, there is a problem that the lead is deformed and the metal thin wire 113 is disconnected.

  The present invention has been made in view of such problems, and the main object of the present invention is to manufacture a circuit device that cleans and roughens the surface of the conductive foil by irradiating the surface of the conductive foil with plasma. It is to provide a method. Furthermore, the main object of the present invention is to provide a method of manufacturing a circuit device that solves problems such as destruction of semiconductor elements that occur when removing contaminants attached to the surface of a conductive material using plasma. It is in.

  The method for manufacturing a circuit device according to the present invention is the method for manufacturing a circuit device in which a conductive foil provided with a convex conductive pattern by forming a separation groove from the surface is used as a material for a conductive member. The surface of the conductive foil including the separation groove is irradiated with plasma from above to roughen the side surface of the separation groove.

  Furthermore, the method for manufacturing a circuit device of the present invention includes a step of forming a separation groove from the surface of the conductive foil to form a convex conductive pattern, a step of electrically connecting a circuit element to the conductive pattern, A step of irradiating the surface of the conductive foil including the separation groove with plasma from above the conductive foil to roughen the side surface of the separation groove; and covering the circuit element and filling the separation groove And a step of sealing with a sealing resin.

  According to the present invention, the side surface of the separation groove can be roughened by plasma ions entering from above the conductive foil. Therefore, it is possible to improve the adhesion strength between the conductive pattern formed from the conductive foil and the sealing resin, and to manufacture a circuit device with excellent quality.

The method for manufacturing a circuit device according to the present invention includes a step of forming a separation groove 11 on the conductive foil 10 from the surface and forming a conductive pattern 21 integrally connected at the bottom, and a circuit element 22 at a desired location of the conductive pattern 21. A circuit device by covering the circuit element 22 and sealing with a sealing resin 28 so as to fill the separation groove 11 and irradiating the surface of the conductive foil 10 with plasma. Manufacturing. There are two methods for plasma irradiation. The first method is a method in which plasma irradiation is performed before the circuit element 22 is mounted. The second method is a method in which plasma irradiation is performed after the circuit element 22 is mounted. How to do it. Details of each of the above steps will be described below.

  As shown in FIGS. 1 to 3, the first step of the present invention is a step of forming a conductive pattern 21 integrally formed at the bottom by forming a separation groove 11 on the conductive foil 10 from the surface.

  In this step, first, a sheet-like conductive foil 10 is prepared as shown in FIG. This conductive foil 10 is selected in consideration of the adhesiveness, bonding property, and plating property of the brazing material. As the material, a conductive foil mainly composed of Cu, a conductive foil mainly composed of Al, or Fe is used. A conductive foil made of an alloy such as Ni is employed.

  Specifically, as shown in FIG. 1B, 4 to 5 blocks 12 in which a large number of mounting portions are formed are arranged on the strip-shaped conductive foil 10 so as to be spaced apart. A slit 13 is provided between each block 12 to absorb the stress of the conductive foil 10 generated by heat treatment in a molding process or the like. In addition, index holes 14 are provided at regular intervals at the upper and lower peripheral ends of the conductive foil 10 and are used for positioning in each step. Subsequently, a conductive pattern 21 for each block is formed.

  First, as shown in FIG. 2, a photoresist (etching resistant mask) PR is formed on the conductive foil 10, and the photoresist PR is patterned so that the conductive foil 10 excluding the region to be the conductive pattern 21 is exposed. Then, as shown in FIG. 3A, the conductive foil 10 is selectively etched through the photoresist PR. The depth of the separation groove 11 formed by etching is, for example, 50 μm, and its side surface is a rough surface, so that the adhesiveness with the sealing resin 28 is improved.

  Further, the side walls of the separation groove 11 have different structures depending on the removing method. This removal process can employ wet etching, dry etching, laser evaporation, and dicing. In the case of wet etching, ferric chloride or cupric chloride is mainly used as the etchant, and the conductive foil 10 is dipped in the etchant or showered with the etchant. Since wet etching is generally non-anisotropic, the side surface has a curved structure.

  A specific conductive pattern 21 is shown in FIG. This figure corresponds to an enlarged view of one of the blocks 12 shown in FIG. One of the parts surrounded by a dotted line is one mounting part 15, which constitutes a conductive pattern 21. A plurality of mounting parts 15 are arranged in a matrix of 5 rows and 10 columns in one block 12, and each mounting part 15 is mounted. The same conductive pattern 21 is provided for each portion 15.

  The second step of the present invention is to mount a circuit element 22 at a desired location of the conductive pattern 21 as shown in FIG. The circuit element 22 is a semiconductor element such as a transistor, a diode, or an IC chip, or a passive element such as a chip capacitor or a chip resistor. Although the thickness is increased, face-down semiconductor elements such as CSP and BGA can also be mounted.

  Here, the bare semiconductor element 22A is die-bonded to the conductive pattern 21, and the electrode of the semiconductor element 22A and the conductive pattern 21 are electrically connected through a fine metal wire. Reference numeral 22B denotes a chip component 22B such as a chip capacitor or a passive element, which is fixed with a conductive paste such as a brazing material 24 such as solder. The third step of the present invention is to perform cleaning by irradiating plasma on the surface of the conductive foil 10 including the circuit element 22 with reference to FIG. FIG. 5A is a view showing an outline of performing plasma cleaning, and FIG. 5B is a cross-sectional view showing a state in which plasma is applied to one mounting portion 15.

  With reference to FIG. 5A, cleaning by plasma irradiation will be described. The plasma cleaner 30 has an upper electrode 31 provided inside the sealed container 34 and a lower electrode 32 provided opposite to the upper electrode 31 and on which the conductive foil 10 is placed. An inlet 35 for supplying gas into the container and an exhaust port 36 for exhausting the gas are provided. Either the upper electrode 31 or the lower electrode 32 is connected to a high frequency power source, and the electrode not connected to the power source is grounded.

  There are two methods of plasma cleaning for conducting contaminants on the surface of the conductive foil: chemical etching and physical etching. Chemical etching includes DP (Direct Plazma) or PE (Plazma Etching), and oxygen can be used as a gas. Physical / chemical etching includes RIE (Reactive Ion Etching), and argon, neon, or helium can be used as a gas. Chemical etching can remove organic contaminants using chemical effects, and physical etching can remove organic and inorganic contaminants using sputtering effects. In the present invention, either method can be used.

  The details of cleaning with plasma will be described with reference to FIG. In the present invention, the plasma irradiation is performed over the entire area of the conductive foil 10. Specifically, ions in the plasma 33 generated by the discharge collide with the entire surface of the conductive foil 10. Accordingly, ions collide with the surface of the conductive pattern 21, the separation groove 11, the circuit element 22, and the fine metal wire 25, and organic or inorganic contaminants attached to these surfaces are removed.

  Contaminants such as residual etchant used in the etching process and dust in the air adhere to the side surfaces of the separation groove 11 and these contaminants are also removed by plasma cleaning. Further, since the separation groove 11 is formed by etching, its side surface is a curved surface. Accordingly, ions entering from above are reflected by the side surface of the separation groove 11, so that one ion collides with the side surface of the separation groove 11 several times. From this, on the side surface of the separation groove 11, the effect of cleaning the surface by ions is great, so that organic and inorganic contaminants attached to the side surface of the separation groove 11 are removed.

  In addition, each conductive pattern 21 is patterned by forming a shallow separation groove 11 in the conductive foil 10 that is a single metal foil, and is integrally connected. Therefore, since each conductive pattern 21 is held in the state of the electrically conductive foil 10 that is electrically integrated, generation of a potential difference due to each conductive pattern is suppressed even when exposed to the influence of plasma. For this reason, even if the semiconductor element 22A is a CMOS or the like that is susceptible to voltage breakdown, damage to the semiconductor element 22A can be minimized.

  Further, the side surface of the separation groove 11 is roughened by plasma cleaning. Therefore, the adhesion between the sealing resin 28 formed in a later step and the side surface of the separation groove 11 is improved. Here, since the side surface of the separation groove 11 is the side surface of the conductive pattern 21, adhesion between the conductive pattern 21 and the sealing resin 28 is improved, and peeling of the conductive pattern 21 can be prevented.

  Furthermore, although the conductive pattern 21 is heated by the plasma cleaning, since the conductive pattern 21 is integrally formed as the conductive foil 10, local thermal expansion and deformation of the conductive pattern 21 are prevented. Therefore, bending or disconnection of the fine metal wire 25 due to expansion or deformation of the conductive pattern 21 can be suppressed.

  Furthermore, the surface of the conductive foil 10 can be oxidized by mixing oxygen into the gas for plasma cleaning. By oxidizing the surface in this way, the adhesion between the sealing resin 28 and the conductive pattern 21 can be further improved.

  With reference to FIG. 5C, in the above description of this process, plasma irradiation was performed on the conductive foil 10 on which the circuit element 22 was mounted. However, before the circuit element 22 was mounted, the conductive foil 10 was It is also possible to irradiate plasma. By performing plasma irradiation in a state where the circuit element 22 is not mounted, it is possible to perform plasma irradiation over the entire surface of the conductive foil 10. In other words, in the state shown in the figure, there is nothing that blocks the plasma irradiation between the surface of the conductive foil 10 that performs plasma irradiation and the separation groove 11 and the upper electrode 31. Thus, the surface of the conductive foil 10 and the separation groove 11 are entirely irradiated with plasma, and contaminants on the surface are removed and the surface is roughened.

  The fourth step of the present invention is to perform sealing with the sealing resin 28 so as to cover the circuit element 22 and fill the separation groove 11 with the sealing resin 28 with reference to FIG.

  With reference to FIG. 6 (A), the state after resin sealing is performed is demonstrated. The sealing resin 28 covers the circuit elements 22 and the plurality of conductive patterns 21, and the separation grooves 11 between the conductive patterns 21 are filled with the sealing resin 28 and are fitted to the curved structures on the side surfaces of the respective conductive patterns 21. Bond firmly. The conductive pattern 21 is supported by the sealing resin 28. In this step, transfer molding can be performed using a thermosetting resin such as an epoxy resin. The merit by this process is that the conductive foil 10 which becomes the conductive pattern 21 becomes a support substrate until the sealing resin 28 is covered. Therefore, there is a merit that the work can be performed with the constituent materials omitted as much as possible, and the cost can be reduced.

  Next, referring to FIG. 7, each conductive pattern 21 is electrically separated by removing the thickness of the conductive foil 10 not provided with the separation groove 11. Specifically, at least the region provided with the conductive pattern 21 of the block 12 of the conductive foil 10 in the thickness portion where the separation groove 11 is not provided is removed. In this step, the entire back surface of the conductive foil 10 is etched until the sealing resin 28 is exposed as shown in FIG. As a result, the back surface of the conductive pattern 21 is exposed to the sealing resin 28.

  The fifth step of the present invention is to separate the sealing resin 28 of the block 12 by dicing for each mounting portion 15 as shown in FIG.

  In this step, the plurality of blocks 12 attached to the pressure-sensitive adhesive sheet are vacuum-adsorbed to the mounting table of the dicing apparatus, and the dicing blade 41 seals the separation grooves 11 along the dicing lines 40 between the mounting portions 15. The resin 28 is diced and separated into individual circuit devices.

  With reference to FIG. 9, the structure of the circuit device manufactured by the above steps will be described. The circuit device shown in FIG. 1 includes a conductive pattern 21, a circuit element 22 fixed on the conductive pattern 21, a metal wire 25 that electrically connects the semiconductor element 22 </ b> A and the conductive pattern 21, and a back surface of the conductive pattern 21. And a sealing resin 28 that supports and seals the whole. The conductive pattern 21 exposed from the back surface of the sealing resin 28 is covered with a resist 26, and external electrodes 27 made of a brazing material such as solder are formed at desired locations.

  According to the circuit device manufacturing method of the present invention, the following effects can be obtained.

  First, since the surface of the conductive foil 10 on which the separation groove 11 for separating the conductive pattern 21 is formed is irradiated with plasma, contaminants attached to the surface can be removed and the surface can be roughened. For this reason, the adhesion between the conductive pattern 21 and the sealing resin 28 can be improved.

  Second, by performing plasma irradiation before mounting the circuit element 22, it is possible to perform plasma irradiation on the entire surface of the conductive foil 10 and the separation groove 11, thereby removing contaminants and roughening the surface. This effect can be further improved.

  Third, it is also possible to perform plasma irradiation after the circuit element 22 is mounted. Since the plasma cleaning is performed in a state where the conductive pattern 21 is electrically integrated as the conductive foil 10, it is possible to suppress the occurrence of a local potential difference in the conductive pattern 21 due to the influence of plasma. Therefore, damage to the semiconductor element 22A due to the potential difference generated by the influence of plasma can be suppressed. Moreover, the surface of the metal fine wire 25 and the circuit element 22 can be cleaned and roughened.

  Fourth, since ions entering from above the conductive foil 10 are reflected by the side surfaces of the separation groove 11, the effect of removing contaminants by plasma irradiation can be further improved.

  Fifth, since the side surface of the separation groove 11 can be roughened by plasma, the adhesion between the sealing resin 28 and the conductive pattern 21 can be further improved.

  Sixth, since the deposit on the surface of the separation groove 11 can be removed by plasma irradiation, the deposit is not removed on the exposed surface of the sealing resin 28 that is filled in the separation groove 11 and exposed on the back surface. Accordingly, the adhesion strength between the sealing resin 28 exposed from the separation groove 11 and the resist 26 can be increased.

  The present invention included in the above-described embodiments includes the following.

  The present invention includes a step of forming a separation pattern on the conductive foil from the surface and forming a conductive pattern integrally connected at the bottom, a step of mounting a circuit element at a desired location of the conductive pattern, and the circuit element Covering and sealing with a resin layer so as to fill the separation groove, and irradiating the surface of the conductive foil with plasma. By irradiating the surface of the conductive foil with plasma, it becomes possible to remove contaminants adhering to the surface of the conductive foil, and further, the surface of the conductive foil can be roughened to improve the adhesion with the insulating resin. It becomes possible.

  In the present invention, the plasma irradiation is performed prior to the step of mounting the circuit element. Thus, by performing plasma irradiation in a state where no circuit element is mounted on the conductive foil, it is possible to perform plasma irradiation over the entire conductive foil. Accordingly, it is possible to perform plasma irradiation on the conductive foil and separation groove regions where circuit elements are to be placed.

  Furthermore, the present invention includes a step of forming a separation groove on the conductive foil from the surface and forming a conductive pattern integrally connected at the bottom, a step of mounting a circuit element at a desired location of the conductive pattern, and the conductive There are a step of irradiating the foil surface with the plasma including the circuit element, and a step of covering the circuit element and sealing with a resin layer so as to fill the separation groove. Since the conductive patterns of the present invention are connected at the bottom, a local potential difference does not occur in the plasma irradiation step, and it is possible to suppress the destruction of circuit elements such as semiconductor elements. Moreover, since the conductive pattern is integrally formed as a conductive foil, there is little deformation due to heating in the process of plasma irradiation. Therefore, deformation and disconnection of the fine metal wire connecting the circuit element and the conductive pattern can be suppressed.

  Furthermore, the present invention removes contaminants attached to the surface of the separation groove by the plasma. Since the irradiated plasma is reflected on the surface of the separation groove, the cleaning effect is further improved by the reflected plasma. Moreover, the surface of the conductive foil is roughened by plasma irradiation, and the adhesion between the conductive pattern and the insulating resin is improved.

  In the present invention, the surface of the conductive foil can be cleaned and roughened by irradiating the surface of the conductive foil with plasma. Furthermore, it is possible to solve problems such as destruction of a semiconductor element that occur when removing contaminants attached to the surface of the conductive material using plasma.

It is sectional drawing (A) and a top view (B) explaining the manufacturing method of the circuit apparatus of this invention. It is sectional drawing explaining the manufacturing method of the circuit apparatus of this invention. It is sectional drawing (A) and a top view (B) explaining the manufacturing method of the circuit apparatus of this invention. It is sectional drawing explaining the manufacturing method of the circuit apparatus of this invention. It is sectional drawing (A), sectional drawing (B), and sectional drawing (C) explaining the manufacturing method of the circuit apparatus of this invention. It is sectional drawing (A) and a top view (B) explaining the manufacturing method of the circuit apparatus of this invention. It is sectional drawing explaining the manufacturing method of the circuit apparatus of this invention. It is a top view explaining the manufacturing method of the circuit device of this invention. It is sectional drawing explaining the manufacturing method of the circuit apparatus of this invention. It is sectional drawing (A)-(D) explaining the manufacturing method of the conventional circuit device. It is the top view (A) and sectional drawing (B) explaining the manufacturing method of the conventional circuit device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Conductive foil 11 Separation groove 12 Block 22A Semiconductor element 22B Chip component 25 Metal thin wire 30 Plasma cleaning machine 31 Upper electrode 32 Lower electrode 40 Dicing line 41 Blade

Claims (4)

In a circuit device comprising a conductive member made of a conductive foil provided with a convex conductive pattern for mounting a semiconductor element by forming a separation groove from the surface,
A side surface of the separation groove provided in the conductive foil is a roughened surface, and the separation groove is filled with a sealing resin for sealing the conductive foil including the semiconductor element, and the conductive foil The circuit device, wherein the sealing resin in the separation groove protrudes from the conductive pattern on the back surface side of the substrate. The circuit device according to claim 1, wherein a resist covers the conductive pattern and the sealing resin protruding from the conductive pattern on a back surface side of the conductive foil. The circuit device according to claim 1, wherein a cross section of the separation groove has a curved shape in which an upper end portion overhangs inward. The circuit device according to claim 1, wherein a surface of the sealing resin protruding from the conductive pattern has an uneven shape.

Images