JP2007266643A - Method for manufacturing circuit device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a thin shape circuit device, using a conductive wiring layer where a periphery with anchor effect has an inverted inclined plane in a semiconductor device, where a flexible sheet having a conductive pattern is used as a support substrate, a semiconductor device is mounted thereon, and the entire structure is molded. <P>SOLUTION: After the conductive wiring layer 14, where the periphery has the inverted inclined plane 14R is formed, by selectively performing field deposition on a laminate 10 where a first conductive film 11 and a second conductive film 12 are laminated, the connection of a sealing resin layer 21 and the layer 14 is strengthened, by putting the layer 21 into the inverted inclined plane 14R to have the anchor effect, when it is covered with the layer 21. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

    The present invention relates to a method for manufacturing a circuit device, and more particularly to a method for manufacturing a thin circuit device using a conductive wiring layer having a reverse inclined surface around an anchor effect.

  In recent years, IC packages are increasingly used in portable devices and small / high-density mounting devices, and conventional IC packages and their mounting concepts are about to change drastically. For example, it is described in JP-A-2000-133678. This is a technology related to a semiconductor device that employs a polyimide resin sheet, which is a flexible sheet, as an example of an insulating resin sheet.

  10 to 12 employ a flexible sheet 50 as an interposer substrate. In addition, the drawing shown above each figure is a top view, and the drawing shown below is sectional drawing of an AA line.

  First, on the flexible sheet 50 shown in FIG. 10, a copper foil pattern 51 is prepared by being bonded via an adhesive. The copper foil pattern 51 differs in pattern depending on the semiconductor element to be mounted depending on the transistor and IC, but generally, a bonding pad 51A and an island 51B are formed. Reference numeral 52 denotes an opening for taking out an electrode from the back surface of the flexible sheet 50, and the copper foil pattern 51 is exposed.

  Subsequently, the flexible sheet 50 is conveyed to a die bonder, and a semiconductor element 53 is mounted as shown in FIG. Thereafter, the flexible sheet 50 is conveyed to a wire bonder, and the bonding pads 51A and the pads of the semiconductor element 53 are electrically connected by the fine metal wires 54.

  Finally, as shown in FIG. 12A, a sealing resin 55 is provided on the surface of the flexible sheet 50 and sealed. Here, transfer molding is performed so as to cover the bonding pad 51A, the island 51B, the semiconductor element 53, and the fine metal wire 54.

  Thereafter, as shown in FIG. 12B, connecting means 56 such as solder or solder balls is provided, and the spherical solder 56 fused to the bonding pad 51A through the opening 52 by passing through a solder reflow furnace. Is formed. Moreover, since the semiconductor elements 53 are formed in a matrix on the flexible sheet 50, they are diced and separated individually as shown in FIG.

In the cross-sectional view shown in FIG. 12C, 51 </ b> A and 51 </ b> D are formed as electrodes on both surfaces of the flexible sheet 50. In general, the flexible sheet 50 is supplied from a manufacturer with both sides patterned.
US Pat. No. 5,976,912 (column 23, line 4 to column 24, line 9, FIGS. 22a to 22g)

  Since the semiconductor device using the flexible sheet 50 described above does not use a known metal frame, it has an advantage that a very small and thin package structure can be realized. However, a single layer of copper provided substantially on the surface of the flexible sheet 50. Wiring is performed only with the foil pattern 51. Since the flexible sheet is soft, distortion occurs before and after the pattern formation of the conductive film, and there is a problem that the positional shift between the layers to be laminated is large and it is not suitable for the multilayer wiring structure.

  In order to improve the support strength in order to suppress the distortion of the sheet, it is necessary to make the flexible sheet 50 sufficiently thick as about 200 μm, which goes against thinning.

  Further, in the manufacturing method, the flexible sheet 50 is transported and mounted on a part called a stage or a table in the above-described manufacturing apparatus such as a die bonder, a wire bonder, a transfer molding apparatus, a reflow furnace, or the like.

  However, if the thickness of the insulating resin serving as the base of the flexible sheet 50 is as thin as about 50 μm, the copper foil pattern 51 formed on the surface is also as thin as 9 to 35 μm and warps as shown in FIG. However, there was a disadvantage that the mounting property to the stage or table was poor. This may be due to warping due to the fact that the insulating resin itself is very thin, and warping due to the difference in thermal expansion coefficient between the copper foil pattern 51 and the insulating resin.

  In addition, since the portion of the opening 52 is pressed from above during molding, a force that warps the periphery of the bonding pad 51A upwards acts, which may deteriorate the adhesion of the bonding pad 51A.

  Further, the resin material constituting the flexible sheet 50 does not have flexibility or becomes hard when a filler is mixed in order to improve thermal conductivity. If bonding is performed with a wire bonder in this state, cracks may occur in the bonding portion. Also, in the case of transfer molding, a crack may occur at a portion where the mold abuts. This appears more prominently when there is a warp as shown in FIG.

  In the flexible sheet 50 described so far, no electrode is formed on the back surface, but as shown in FIG. 12C, the electrode 51D may be formed on the back surface of the flexible sheet 50 in some cases. At this time, since the electrode 51D is in contact with the manufacturing apparatus or in contact with the transport surface of the transport means between the manufacturing apparatuses, there is a problem in that the back surface of the electrode 51D is damaged. Since the electrode is formed with this damage, there is a problem that the electrode 51D itself cracks when heat is applied later, and a problem that solder wettability is lowered when solder is connected to the motherboard.

  In addition, there is a problem that a sufficient sealing structure cannot be realized due to weak adhesion between the flexible sheet 50 and the copper foil pattern 51 and the insulating resin during transfer molding.

  The present invention provides a step of preparing a substrate in which a first conductive film and a second conductive film covering one main surface of the first conductive film are laminated, and selectively on the second conductive film. Forming a conductive wiring layer having a reverse inclined surface on the periphery, removing the second conductive film using the conductive wiring layer as a mask, and fixing a semiconductor element on the first conductive film. Electrically connecting the electrode of the semiconductor element and the predetermined conductive wiring layer; covering the semiconductor element with a sealing resin layer; and the sealing resin layer on the reverse inclined surface of the conductive wiring layer And a step of removing the first conductive film to expose the second conductive film on the back surface of the sealing resin layer and the conductive wiring layer. And In particular, it is characterized in that a reverse slope is formed around the conductive wiring layer to give an anchor effect of the sealing resin layer.

  The present invention is characterized in that the second conductive film is formed by silver electroplating.

  The present invention is characterized in that the conductive wiring layer is formed by electroplating of copper using the first conductive film as an electrode.

The present invention is characterized in that an external electrode is formed by attaching a brazing material to the remaining second conductive film.

  According to the present invention, in the step of forming the conductive wiring layer, the anchor effect between the conductive wiring layer and the sealing resin layer can be strengthened by forming a reversely inclined surface in the conductive wiring layer. There is an advantage that a good sealing state can be realized because the biting between the conductive layer and the conductive wiring layer becomes strong.

  Further, since the second conductive film functions as an etching barrier layer together with the sealing resin layer when the entire first conductive film is removed, there is an advantage that the first conductive film can be removed without a mask.

  Further, since the second conductive film forms a sealing resin layer and a flat back surface, it can be adopted in either a land grid array structure or a ball grid array structure, and the remaining third conductive film itself is the entire external electrode or one of the external electrodes. There is an advantage that the part can be configured.

  A method for manufacturing a circuit device according to the present invention will be described with reference to FIGS.

The method for manufacturing a circuit device according to the present invention includes a step of preparing a substrate 10 in which a first conductive film 11 and a second conductive film 12 covering one main surface of the first conductive film 11 are laminated, A step of selectively forming a conductive wiring layer 14 having a reverse inclined surface 14R around the second conductive film 12 and a step of removing the second conductive film 12 using the conductive wiring layer 14 as a mask. A step of fixing the semiconductor element 17 on the first conductive film 11 and electrically connecting the electrode of the semiconductor element 17 to the predetermined conductive wiring layer 14; and sealing the semiconductor element 17 with a sealing resin. A step of covering with the layer 21, and causing the sealing resin layer 21 to have an anchor effect at the reverse inclined surface 14R of the conductive wiring layer 14, and removing the first conductive film 11 to form the sealing resin layer 21. And the second conductive film 1 on the back surface of the conductive wiring layer 14. It is composed of a step of exposing the. Each of these steps will be described below.

A step of covering the second conductive film 12 with a photoresist layer PR having a desired pattern and an inclined surface 13S inclined to the opening 13; and a conductive wiring layer 14 is selectively applied to the opening 13 of the photoresist layer PR. Forming,

As shown in FIG. 1, the first step of the present invention is a substrate 10 in which a first conductive film 11 and a second conductive film 12 covering one main surface of the first conductive film 11 are laminated. Is to prepare.

  The surface of the laminate 10 is such that the first conductive film 11 is formed over substantially the entire area, and the second conductive film 12 is formed on the surface thereof. The first conductive film 11 is preferably made of a material mainly composed of Cu or a known lead frame material. The first conductive film 11 and the second conductive film 12 may be formed by a plating method, a vapor deposition method or a sputtering method, or a metal foil formed by a rolling method or a plating method may be attached. The first conductive film 11 may be Al, Fe, Fe—Ni, a known lead frame material, or the like.

  As the material of the second conductive film 12, a material that is not etched is used as an etchant used when removing the first conductive film 11. In addition, since the external electrode 24 made of solder or the like is formed on the back surface of the second conductive film 12, the adhesion of the external electrode 24 is also taken into consideration. Specifically, as the material of the second conductive film 12, a conductive material made of gold, silver, or palladium can be used.

  The first conductive film 11 is formed thick to support the whole mechanically, and the thickness is about 35 to 150 μm. The second conductive film 12 functions as a barrier layer when the first conductive film 11 is etched, and has a thickness of about 2 to 20 μm. Therefore, by forming the first conductive film 11 thick, the flatness of the laminated plate 10 can be maintained, and the workability of the subsequent process can be improved.

  Furthermore, the first conductive film 11 is damaged due to various processes. However, since the first conductive film 11 is removed in a later step, it is possible to prevent the finished circuit device from being damaged. Further, since the sealing resin can be cured while maintaining the flatness, the back surface of the package can be flattened, and the external electrodes formed on the back surface of the laminated plate 10 can also be arranged flat. Therefore, the electrode on the mounting substrate and the electrode on the back surface of the laminated plate 10 can be brought into contact with each other, and a solder failure can be prevented.

  Next, a specific method for manufacturing the above-described laminated plate 10 will be described. The laminated plate 10 can be manufactured by electroplating or roll bonding. When manufacturing the laminated board 10 by electroplating, the 1st electrically conductive film 11 is prepared first. Then, an electrode is provided on the back surface of the first conductive film 11, and the second conductive film 12 is laminated by an electroplating method. When manufacturing a laminated board by rolling, the 1st electrically conductive film 11 and the 2nd electrically conductive film 12 which were prepared in plate shape are joined by applying a pressure with a roll.

  The second step of the present invention is to selectively form a conductive wiring layer 14 having a reverse inclined surface 14R around it on the second conductive film 12, as shown in FIGS.

  In this step, as shown in FIG. 2, the second conductive film 12 is covered with a photoresist layer PR having a desired pattern and an inclined surface 13S inclined to the opening 13. That is, after the second conductive film 12 is covered with the photoresist layer PR, exposure and development are performed to form the opening 13 in the shape of a desired wiring pattern, and the photoresist layer PR corresponding to the opening 13 is developed. Remove with liquid.

  Next, as shown in FIG. 2, an inclined surface 13S is formed in the opening 13 of the photoresist layer PR. In the first method, the photoresist layer PR after development is heated to about 120 to 180 ° C. to form an inclined surface 13S inclined upward. In the second method, a positive photoresist material is used as the photoresist layer PR, so that an inclined surface 13 </ b> S that spreads upward and is inclined when developed is developed due to poor resolution.

  Subsequently, as shown in FIGS. 3 and 4, a conductive wiring layer 14 is selectively formed in the opening 13 of the photoresist layer PR, and a reverse inclined surface 14 </ b> R is provided around the conductive wiring layer 14. That is, the conductive wiring layer 14 is formed by selectively electrolytically plating copper in the opening 13 of the photoresist layer PR using the first conductive film 11 as a common electrode. At this time, the photoresist layer PR functions as a mask, and the conductive wiring layer 14 is formed in a desired pattern on the second conductive film 12 where the opening 13 is exposed. The conductive wiring layer 14 is formed to a thickness of about 20 μm so as to embed the opening 13 of the photoresist layer PR, and a reverse inclined surface 14R is formed on the periphery of the conductive wiring layer 14 in contact with the photoresist layer PR. It is formed with a reverse slope with 13S. The conductive wiring layer 14 is Cu here, but may be Au, Ag, Pd, or the like.

  Further, as shown in FIG. 4, a pad 15 </ b> A made of the third conductive film 15 is selectively formed on the conductive wiring layer 14. The conductive wiring layer 14 is covered with a photoresist layer PR except for a region where a pad is to be formed, and after nickel is plated, gold or silver is electroplated to form a pad 15A. At this time, the back surface of the first conductive film 11 is covered with a photoresist layer PR or an overcoat resin to prevent formation of a pad.

  As shown in FIG. 5, the third step of the present invention is to remove the second conductive film 12 using the conductive wiring layer 14 as a mask.

  In this step, the photoresist layer PR is removed, and the second conductive film 12 is selectively etched away using the conductive wiring layer 14 as a mask. The etchant used here is one that etches the second conductive film 12 and does not etch the conductive wiring layer 14. That is, when the conductive wiring layer 14 is formed of a material mainly composed of Cu and the second conductive film 12 is silver, only the second conductive film 12 is removed by using an iodine-based etchant. be able to. When the pad 15A is made of silver, it is removed by this etching, so it needs to be protected by covering it with a photoresist layer (not shown).

  The remaining second conductive film 12 serves as an external electrode 24.

  In the fourth step of the present invention, as shown in FIG. 6, the semiconductor element 17 is fixed on the first conductive film 11, and the electrode of the semiconductor element 17 and the predetermined conductive wiring layer 14 are electrically connected. There is.

  The semiconductor element 17 is die-bonded on the first conductive film 11 with an insulating adhesive resin 18 as a bare chip.

  Each electrode pad of the semiconductor element 17 is connected by a bonding wire 19 to a pad 15A provided at a predetermined position of the conductive wiring layer 14 provided in the periphery. The semiconductor element 17 may be mounted face down. In this case, solder balls and bumps are provided on the surface of each electrode pad of the semiconductor element 17, and electrodes similar to the bonding pads made of the conductive wiring layer 14 are provided on the surface of the laminated board 10 at portions corresponding to the positions of the solder balls. It is done.

  The merit of using the laminate 10 at the time of wire bond ink will be described. Generally, when wire bonding of Au wire is performed, it is heated to 200 ° C to 300 ° C. At this time, if the first conductive film 11 is thin, the laminated plate 10 warps, and if the laminated plate 10 is pressed through the bonding head in this state, the laminated plate 10 may be damaged. However, these problems can be solved by forming the first conductive film 11 to be thick.

  In the fifth step of the present invention, as shown in FIG. 7, the semiconductor element 17 is covered with the sealing resin layer 21, and an anchor effect is generated in the sealing resin layer 21 by the reverse inclined surface 14 </ b> R of the conductive wiring layer 14. There is.

  The laminated plate 10 is set in a molding apparatus and performs resin molding. As a molding method, transfer molding, injection molding, coating, dipping and the like are also possible. However, in view of mass productivity, transfer molds and injection molds are suitable.

  In this step, when molding is performed with the sealing resin layer 21, the sealing resin layer 21 is filled into the reverse inclined surface 14R of the conductive wiring layer 14 formed on the surface of the first conductive film 11, and the sealing resin layer There is an advantage that the coupling between the conductive layer 21 and the conductive wiring layer 14 is strengthened by the anchor effect.

  In this step, the laminated plate 10 needs to be in flat contact with the lower mold of the mold cavity, but the thick first conductive film 11 performs this function. Moreover, even after removal from the mold cavity, the flatness of the package is maintained by the first conductive film 11 until the shrinkage of the sealing resin layer 21 is completely completed. That is, the first conductive film 11 plays the role of mechanical support of the laminated plate 10 up to this step.

  The sixth step of the present invention is to remove the first conductive film 11 and expose the second conductive film 12 on the back surface of the sealing resin layer 21 and the conductive wiring layer 14 as shown in FIG. is there.

  In this step, the first conductive film 11 is etched so that the entire surface is removed without a mask. This etching may be chemical etching using ferric chloride or cupric chloride, and the first conductive film 11 is entirely removed. Thus, the second conductive film 12 left by removing the first conductive film 11 entirely is exposed from the sealing resin layer 21. As described above, since the second conductive film 12 is formed of a material that is not etched by the solution for etching the first conductive film 11, the second conductive film 12 is not etched in this step.

  The feature of this step is that, when the first conductive film 11 is removed by etching, the sealing resin layer 21 and the second conductive film 12 function as a barrier layer without using a mask. The back surface made of the second conductive film 12 is formed flat. Since the first conductive film 11 is entirely removed by etching, the second conductive film 12 is also in contact with the etchant at the final stage of etching. As described above, the second conductive film 12 is made of a material that is not etched by ferric chloride and cupric chloride that etch the first conductive film 11 made of Cu. Therefore, the etching stops on the lower surface of the second conductive film, and the second conductive film 12 functions as an etching barrier layer. In addition, after this process, the whole is mechanically supported by the sealing resin layer 21.

  The final step of the present invention is to form a land grid array structure or a ball grid array structure as shown in FIG.

  In the case of the land grid array structure, the second conductive film 12 is covered with the overcoat resin 23 except for the portion that becomes the external electrode 24 from the previous process in which the first conductive film 11 is entirely removed, and the sealing resin layer 21 and The overcoat resin 23 is diced to separate them into individual circuit devices.

  In the case of the ball grid array structure, the second conductive film 12 exposes a portion where the external electrode 24 is formed and screen-prints an epoxy resin or the like dissolved in a solvent and covers the majority with the overcoat resin 23. Next, an external electrode 24B protruding from the exposed portion is formed by screen printing of solder cream and reflow of solder. Subsequently, since a large number of circuit devices are formed on the laminated plate 10 in a matrix, the sealing resin layer 21 and the overcoat resin 23 are diced to separate them into individual circuit devices.

  In this step, since the sealing resin layer 21 and the overcoat resin 23 can be separated into individual circuit devices by dicing, wear of a dicer that performs dicing can be reduced.

It is sectional drawing 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 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 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 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 explaining the manufacturing method of the circuit apparatus of this invention. It is a figure explaining the manufacturing method of the conventional semiconductor device. It is a figure explaining the manufacturing method of the conventional semiconductor device. It is a figure explaining the manufacturing method of the conventional semiconductor device. It is a figure explaining the conventional flexible sheet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Laminated board 11 1st electrically conductive film 12 2nd electrically conductive film 14R Reverse inclined surface 16 Anchor part 17 Semiconductor element 19 Bonding wire 21 Sealing resin layer 23 Overcoat resin 24 External electrode

Claims (4)

Preparing a substrate in which a first conductive film and a second conductive film covering one main surface of the first conductive film are laminated;
Forming a conductive wiring layer selectively provided with a reverse inclined surface around the second conductive film;
Removing the second conductive film using the conductive wiring layer as a mask;
Fixing a semiconductor element on the first conductive film and electrically connecting an electrode of the semiconductor element and the predetermined conductive wiring layer;
Covering the semiconductor element with a sealing resin layer, and generating an anchor effect on the sealing resin layer at the reversely inclined surface of the conductive wiring layer;
And removing the first conductive film to expose the second conductive film on the back surface of the sealing resin layer and the conductive wiring layer. 2. The method of manufacturing a circuit device according to claim 1, wherein the second conductive film is formed by silver electroplating. 2. The method of manufacturing a circuit device according to claim 1, wherein the conductive wiring layer is formed by copper electroplating using the first conductive film as an electrode. 2. The method of manufacturing a circuit device according to claim 1, wherein a brazing material is attached to the remaining second conductive film to form an external electrode.