JP2006216977A - Semiconductor device - Google Patents

Abstract

A semiconductor device of a leadless surface mounting system is provided with high reliability, a small size, and a thin type, and improved reliability and excellent reliability.
A metal layer 2a on which a semiconductor element S is mounted, one or more electrode layers 2b arranged around the metal layer 2a at a predetermined interval, and a semiconductor element mounted on the metal layer 2a A semiconductor in which S and the electrode layer 2b are resin-sealed in a state where they are electrically connected by a method such as wire bonding, and the back surfaces of the metal layer 2a and the electrode layer 2b are exposed from the bottom surface of the resin layer 4 The device has a structure in which the periphery of the upper end of each of the metal layer 2a and the electrode layer 2b to be resin-sealed extends in a bowl shape and bites into the resin layer 4.
[Selection] Figure 1

Description

  The present invention relates to a semiconductor device, and more particularly to a resin-encapsulated semiconductor device that can be reduced in size and thickness and has high reliability.

  As this type of semiconductor device, for example, using a pattern metal such as a lead frame, a semiconductor element mounted on the lead frame and an external terminal formed on the lead frame are electrically connected and then resin-sealed. There is a small semiconductor device in which an external terminal is exposed.

  In order to reduce the size or thickness of such a semiconductor device, resin sealing is performed only on one side of the lead frame on which the semiconductor element is mounted, and external terminals of the lead frame are exposed from the resin sealing bottom side. The structure is used.

  However, in such a semiconductor device, since the adhesion strength between the lead frame serving as the external terminal and the sealing resin is low, there are some cases in which the resin peels off or the lead frame external terminal comes out, and the reliability of the device is high. It is seriously damaged.

  The object of the present invention is proposed to solve such conventional problems, and in manufacturing a small and thin semiconductor device, the components constituting the device are firmly bound in a sealing resin. Another object of the present invention is to provide a highly reliable semiconductor device structure.

  The present invention is for solving the above-described problem, and includes a metal layer 2a on which a semiconductor element S is mounted, and one or more electrode layers 2b disposed around the metal layer 2a at a predetermined interval. Then, the semiconductor element S mounted on the metal layer 2a and the electrode layer 2b are resin-sealed in a state where they are electrically connected by a method such as wire bonding, and the back surfaces of the metal layer 2a and the electrode layer 2b are bonded to each other. In the semiconductor device formed to be exposed from the bottom surface of the resin layer 4, the periphery of the upper end of each of the metal layer 2a and the electrode layer 2b to be resin-sealed is formed so as to project in a bowl shape.

  As described above, according to the present invention, the resin layer in which the back surface of each of the metal layer 2a on which the semiconductor element S is mounted and the electrode layer 2b electrically connected to the semiconductor element S is a sealing resin. As a form exposed from the bottom surface of the semiconductor device 4, the semiconductor device is made small and thin and has excellent heat dissipation characteristics. Further, the semiconductor device is intentionally formed on the periphery of the upper end of the metal layer 2a or the electrode layer 2b. In the resin sealing step, the overhanging portions 11 are positioned in a bite shape with respect to the resin layer 4 by forming the flange-like overhanging portions 11, so that the metal layer 2 a, the electrode layer 2 b, and the resin layer 4 can be improved and defects such as resin peeling and misalignment can be surely prevented, and quality and reliability after commercialization can be improved. In addition, the unique shape of the ridge-like overhanging portion 11 has an effect of preventing moisture and the like from entering the surface side of the metal layer 2a and the electrode layer 2b and also increasing the creepage distance. It is also possible to improve the water resistance and moisture resistance.

An embodiment of the present invention will be described with reference to the drawings.
1A and 1B show a leadless surface mounting type semiconductor device according to the present invention, in which FIG. 1A is a sectional view and FIG. 1B is a bottom view. In the figure, S is a semiconductor element, which is mounted on the metal layer 2a by bonding. L is an electrode formed on the semiconductor element S, and is connected and electrically connected by a corresponding electrode layer 2b arranged in parallel with the metal layer 2a by a conductive wire 3 such as gold. Yes. The mounting portion of the semiconductor element S is sealed with a resin layer 4 such as a thermosetting epoxy resin, and a resin sealing body is formed in which the back surfaces of the metal layer 2a and the electrode layer 2b are exposed.
In addition, projecting portions 11 and 11 projecting in a cross-sectional shape are integrally formed on the periphery of the upper end portions of the metal layer 2a and the electrode layer 2b. Due to the presence of the overhang portions 11, 11, the binding strength with the resin layer 4 is improved.

  Next, the semiconductor device manufacturing method according to the above embodiment will be described in detail. FIGS. 2 and 3 show the semiconductor device manufacturing method for each process, and FIG. 2A shows stainless steel, aluminum, copper, and the like. A conductive resist plate, such as laminating an alkali type photosensitive film resist having a thickness of about 50 μm on both surfaces of a substrate 1 having a thickness of 0.1 mm formed by SUS430 in this embodiment, and the like. 5 and 5, and after performing double-sided exposure by ultraviolet irradiation in a state where a film F having a predetermined pattern is arranged on the photosensitive resist layer 5 on one side of the substrate 1 as shown in FIG. Development processing is performed to obtain a resist pattern layer 6 having a predetermined patterning on one surface side of the substrate 1 and a cured resist layer 5 on the back surface thereof as shown in FIG.

  Next, after the surface activation treatment such as removal of the surface oxide film by chemical etching or well-known chemical treatment with chemicals is performed on the exposed surface not covered with the resist pattern layer 6 on the one surface side of the substrate 1 as necessary. Then, electroforming is performed on the substrate 1, and an electrodeposit of conductive metal is grown from the exposed surface defined by the resist pattern layer 6 of the substrate 1 as shown in FIG. One or more independent electrode layers 2b are paired with the metal layer 2a, and a plurality of sets are formed in parallel. In addition, although nickel, nickel-cobalt alloy, copper, and various other metals can be considered as electrodeposits, in this embodiment, a matte bath of nickel sulfamate is used, and an enlarged view of the AA portion of this figure. As shown in FIG. 4, by so-called overhang that is electrodeposited beyond the thickness of the resist pattern layer 6, after removing the resist pattern layer 6 as will be described later, FIG. 2 (e) and BB in FIG. As shown in FIG. 5, which is an enlarged view of the portion, overhanging portions 11 and 11 having a bowl-shaped cross section are integrally formed on the periphery of the upper end portions of the metal layer 2a and the electrode layer 2b. Here, the surface activation process is not an essential process.

  After the electroforming step according to FIG. 2D, the surface of each metal layer 2a and electrode layer 2b is subjected to gold plating for improving the binding force to a thickness of 0.3 to 0.4 μm as necessary, and both surfaces of the substrate 1 are formed. By removing the resist pattern layer 6 and the resist layer 5 further, the state of FIG. In addition, as a method for removing the resist, a method for removing swelling with an alkaline solution, or the like can be considered.

  Next, as shown in FIG. 3A, the semiconductor element S is mounted on the metal layer 2a by a known method, and the electrode L 2b corresponding to the electrode L on the semiconductor element S is shown in FIG. As in 3 (b), the wire is connected by an ultrasonic bonding apparatus or the like using a conductive wire 3 such as a gold wire. Here, when the wires 3 are connected, each electrode layer 2b is subjected to a pulling force from the bonding apparatus and tends to float from the substrate 1. As described above, prior to the electroforming process, By performing surface activation treatment on the exposed surface, the adhesion between the substrate 1 and the electrodeposition layer has been improved in advance, so that it is possible to effectively prevent the electrode layer 2b from falling off and rising during connection, and the manufacturing process. The defective product formation rate can be reduced.

  Next, the semiconductor element S mounting portion on the substrate 1 is molded with a resin layer 4 such as a thermosetting epoxy resin as shown in FIG. 3C to form a resin sealing body on the substrate 1. Specifically, a plurality of sets of semiconductors are formed in parallel on the substrate 1 by mounting one side of the substrate 1 to a mold die (upper die) and pressing an epoxy resin into the mold die through a cavity. The element mounting portion is continuously sealed by the resin layer 4. In this case, the substrate 1 itself functions as a lower mold during resin molding. If a plurality of substrates 1 are arranged in parallel at the time of molding and an epoxy resin is press-fitted between each substrate 1 and the upper mold through a liner, a large number of resins can be sealed efficiently. It is.

Next, as shown in FIG. 3D, by removing the substrate 1 from the resin sealing body, the back surfaces of the plurality of sets of metal layers 2a and electrode layers 2b are exposed on the bottom surface of the resin sealing body, and the metal The back surfaces of the layer 2a and the electrode layer 2b and the bottom surface of the resin layer 4 are substantially in the same plane. Here, if the overhanging portions 11 and 11 are formed on the peripheral edges of the metal layer 2a and the electrode layer 2b as described above, the resin layer 4 can be separated into the resin layer 4 as shown in FIG. Since the overhanging portions 11 and 11 are hardened in a state of being bitten, the metal layer 2a and the metal layer 2a are removed when the substrate 1 is peeled off during the peeling operation of the substrate 1 from the resin sealing body. The electrode layer 2b reliably remains on the resin layer 4 side and does not stick to and separate from the substrate 1, and can be effectively prevented from being displaced or missing, thereby improving the yield during the manufacturing process.
As a method for removing the substrate 1, in addition to a method for forcibly peeling and removing the substrate 1 from the resin sealing body, for example, depending on the material constituting the substrate 1, A method of dissolving and removing the substrate 1 with an unaffected solvent or the like is also included. In addition, if necessary after this step, a thin film of a conductive gold layer such as gold or silver is mounted on only the back surface of each electrode layer 2b or the electrode layer 2b and the metal layer 2a by a known method such as flash plating. You may make it form by 0.3-0.5 micrometer thickness.

  Next, as shown in FIG. 3 (e), the resin sealing body is cut along a cutting line XX for each pair of semiconductor elements and separated into individual resin sealing bodies, that is, in FIG. The semiconductor device shown is completed.

  According to the semiconductor device having the above-described configuration, in particular, due to the presence of the overhanging portion 11 having a specific ridge shape, the semiconductor device enters from a minute gap between the metal layer 2a and the resin layer 4 on the back surface side of the electrode layer 2b. Moisture or the like is blocked by the bowl-shaped overhanging portion 11 and has an effect of preventing entry into the upper portion, that is, the connection portion or the semiconductor element mounting portion, and the water resistance to the connection portion with the semiconductor element S or the wire is improved. Further, regarding the reliability of the completed semiconductor device itself, the protruding portions 11 and 11 at the periphery of the upper end of each of the metal layer 2a and the electrode layer 2b are arranged in a state of biting into the resin layer 4, The adhesion strength between the layer 2a and the electrode layer 2b and the resin layer 4 is remarkably improved, and the quality can be improved without causing defects such as resin peeling and displacement.

In addition, as for each overhang | projection part 11, as a result of having verified by experiment by the applicant, length T grows substantially in proportion to the height which overhangs exceeding the thickness of the resist pattern layer 6, The length When T is 5 μm or less, the biting effect on the resin layer 4 at the time of molding is weak, and when the substrate 1 is peeled off, the metal layer 2a and the electrode layer 2b are slightly adhered to and separated from the substrate 1 side. It is preferable to set the length longer than this because there is a phenomenon of missing. When the thickness exceeds 20 μm, the resist pattern layer 6 is swelled and removed by an alkaline solvent when the resist pattern layer 6 is removed after the electrodeposition step. There is a possibility that the resist pattern layer 6 swollen sometimes floats the electrodeposited metal (metal layer 2a, electrode layer 2b) from the substrate 1 through the overhanging portions 11 and 11. Therefore, in view of these points, it is preferable to set within a range of 5 to 20 μm.

(Other examples)
It should be noted that when the resin is sealed, either one or both of the metal layer 2a and the back surface of the electrode layer 2b may be configured to protrude slightly from the back surface of the resin layer 4. Further, gold, silver, or the like may be formed on the back surface of the metal layer 2a, the electrode layer 2b, or the like by a method such as flash plating. Further, the back surfaces of the metal layer 2a and the electrode layer 2b can be configured to be slightly recessed from the back surface of the resin layer 4.

(A) is sectional drawing which shows one Example of the semiconductor device of this invention, (b) is the back view. (A) thru | or (e) is sectional drawing explaining the manufacturing method of the semiconductor device shown in 1st Example of this invention. (A) thru | or (e) is sectional drawing explaining the manufacturing method of the semiconductor device following FIG.2 (e). It is sectional drawing (partially enlarged view) which expanded the AA part of FIG.2 (d). It is sectional drawing (partially enlarged view) which expanded the BB part of FIG.2 (e).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Board | substrate 2a Metal layer 2b Electrode layer 4 Resin layer 6 Resist pattern layer S Semiconductor element

Claims (1)

  A metal layer 2a on which the semiconductor element S is mounted, one or more electrode layers 2b disposed around the metal layer 2a at a predetermined interval, and a semiconductor element S and an electrode layer mounted on the metal layer 2a In a semiconductor device in which resin 2 is sealed in a state where it is electrically connected by a method such as wire bonding, and the back surfaces of the metal layer 2a and the electrode layer 2b are exposed from the bottom surface of the resin layer 4. A semiconductor device characterized in that the upper edge of each of the metal layer 2a and the electrode layer 2b to be sealed is formed so as to project in a bowl shape.

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