JP2005101270A - Packaging structure of semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packaging structure of a semiconductor device in which a difference in a bonding strength between a conductive material and the semiconductor device and between the conductive material and a substrate can be reduced, and the bonding strength between the conductive material and the substrate can be increased. <P>SOLUTION: In the packaging structure of the semiconductor device, a plurality of electrode pads 5 are disposed on a substrate 1 in which a plurality of connection pads 3 are disposed to form a semiconductor device 4, which is arranged so that the connection pads 3 faces the electrode pads 5, and the both are connected to each other by a conductive material 6. Regarding the electrode pads 5 and the connection pads 3 which face each other, one pad area is made larger than the other, and also a size relation of both is alternately reversed along the arrangement of the pad. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

 The present invention relates to a semiconductor element mounting structure mounted on a circuit board by face-down bonding.

Conventionally, a semiconductor element mounted by face-down bonding is known.
In addition to the electronic circuit formed with high density, a plurality of electrode pads are provided on the lower surface of the semiconductor element used for the face-down bonding, and these terminals are connected to the connection pads of the circuit board by a conductive material such as solder. A semiconductor element is mounted on a circuit board by connecting via a material.

  The connection pad is formed by depositing gold, nickel or the like on one end portion of the circuit conductor to a thickness of 1 μm to 5 μm in order to improve the wettability of the conductive material. The connection between the pads and the circuit conductor on the circuit board is made more reliable by bonding them with a conductive material.

By the way, the electrode pad of a semiconductor element used as a head driving IC such as a thermal head or an LED head and the connection pad on the circuit board have a large area on either the electrode pad side or the connection pad side, In general, it is formed small.
JP-A-1-179425 JP-A-10-129024

  However, in the configurations as described in Patent Document 1 and Patent Document 2 described above, the pad area is always increased on either the electrode pad side or the connection pad side, so that the bonding strength between the conductive material and the semiconductor element and the conductivity are increased. The balance with the bonding strength between the material and the circuit board is deteriorated. For example, as in Patent Document 1, when the pad area is small on the semiconductor element side, the contact area between the conductive material and the electrode pad is significantly smaller than the contact area between the conductive material and the contact pad. The joint strength tends to be insufficient. For this reason, when an external force is applied to the junction between the semiconductor element and the circuit board, there is a problem that cracks, cracks, and the like are likely to occur at the boundary between the conductive material and the electrode pad.

  The present invention has been devised in view of the above problems, and its purpose is to reduce the difference in bonding strength between the conductive material and the semiconductor element and between the conductive material and the circuit board, and to bond the semiconductor element and the circuit board. An object of the present invention is to provide a semiconductor element mounting structure capable of increasing strength.

  According to the semiconductor element mounting structure of the present invention, a semiconductor element having a plurality of electrode pads arranged on a substrate on which a plurality of connection pads are arranged is arranged so that the connection pads and the electrode pads face each other. In the semiconductor element mounting structure in which the two are connected by a conductive material, one of the electrode pads and the connection pads facing each other has a larger pad area than the other, and the size of the two pad areas is large or small. The relationship is alternately reversed along the arrangement of the pads.

  The semiconductor element mounting structure according to the present invention is characterized in that, in the above-described semiconductor element mounting structure, the conductive material has a trapezoidal cross section.

  Further, the semiconductor element mounting structure of the present invention is the above-described semiconductor element mounting structure, wherein the electrode pads and the connection pads are arranged in a plurality of rows, and the electrode pads and the connection pads facing each other in adjacent rows. It is characterized in that the magnitude relation of is reversed.

  According to the semiconductor element mounting structure of the present invention, among the electrode pads of the semiconductor elements facing each other and the connection pads on the substrate, one of the pad areas is made larger than the other, and the relationship between the two pad areas is large or small. Are alternately inverted along the arrangement of the pads, so that the difference in the contact area between the conductive material and the electrode pad and the contact area between the conductive material and the connection pad can be made smaller than before. Accordingly, it is possible to reduce the difference in bonding strength between the conductive material and the semiconductor element and between the conductive material and the substrate, and to effectively prevent any one of the bonding strengths from becoming extremely weak, and to reduce the bonding strength between the semiconductor element and the substrate. It becomes possible to raise.

  According to the semiconductor element mounting structure of the present invention, the electrode pads and the connection pads are arranged in a plurality of rows, and the size relationship between the electrode pads and the connection pads facing each other in the adjacent rows is reversed. Therefore, the difference in bonding strength between the conductive material and the electrode pad and between the conductive material and the connection pad can be further reduced as compared with the conventional case.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an embodiment in which the mounting structure of the present invention is applied to a thermal head, FIG. 2 is an enlarged view of a main part of the thermal head in FIG. 1, and FIG. 3 shows a semiconductor element mounted on the thermal head in FIG. 1 is a plan view seen from one main surface side, where 1 is a substrate, 2 is a circuit conductor, 3 is a connection pad, 4 is a semiconductor element, 5 is an electrode pad, 6 is a conductive material, and 7 is a sealing material.

  The substrate 1 is formed in a quadrangular shape by various materials such as an electrically insulating material such as alumina ceramics and glass and a semiconductor material having an insulating film formed on the surface, and a plurality of heating elements R and a plurality of heating elements R are formed on the upper surface thereof. The circuit conductor 2, the connection pad 3, the semiconductor element 4, the sealing material 7 and the like are supported.

  When the substrate 1 is made of, for example, alumina ceramics, an appropriate organic solvent or an organic solvent is added to and mixed with ceramic raw material powder such as alumina, silica, magnesia, etc. to form a slurry, and this is made into a conventionally known doctor blade method or the like. Is used to obtain a ceramic green sheet, and thereafter, the ceramic green sheet is punched into a predetermined shape and then fired at a high temperature (about 1600 ° C.).

  The circuit conductor 2 deposited and formed on the upper surface of the substrate 1 applies an output generated from the electrode pad 5 of the semiconductor element 4 (head driving IC) to the heating element R when applied to, for example, a thermal head. This serves as a signal wiring for supplying the semiconductor element 4 with a power supply wiring and an external print signal.

  Such a circuit conductor 2 is formed by coating a metal such as aluminum with a predetermined thickness and a predetermined pattern on the upper surface of the substrate 1 by adopting a conventionally well-known thin film technique, specifically, sputtering, photolithography technique, etching technique or the like. Wear and form.

  A plurality of connection pads 3 each having a substantially quadrangular shape are attached to some upper surfaces of the plurality of circuit conductors 2.

  The connection pads 3 are arranged in a plurality of rows along the long side of the semiconductor element 4 to be described later, and are arranged in the horizontal direction (direction along the long side of the semiconductor element 4) and in the vertical direction (perpendicular to the long side of the semiconductor element 4). Large area pads and small area pads are alternately arranged in each direction.

  These connection pads 3 are electrically connected to the electrode pads 5 of the semiconductor element 4 through the conductive material 6, and a metal having good wettability to the conductive material 6, for example, the conductive material 6 is made of solder. In this case, gold, nickel, or the like is formed on one end of the circuit conductor 2 to a thickness of 1 μm to 5 μm. Therefore, when the semiconductor element 4 is mounted, the conductive material 6 gets wet well, and the connection between the electrode pad 5 of the semiconductor element 4 and the connection pad 3 on the substrate 1 becomes more reliable.

  The connection pads 3 are deposited and formed on a part of the surface of the circuit conductor 2 so as to have a predetermined thickness and a predetermined pattern by employing a conventionally known electroless plating method or the like.

  A plurality of electrode pads 5 provided on one main surface of the semiconductor element 4 are connected to the plurality of connection pads 3 described above via a conductive material 6.

  The semiconductor element 4 has a structure in which a plurality of rectangular electrode pads 5 are formed on one main surface of a rectangular plate made of single crystal silicon so as to correspond to the connection pads 3 on the substrate 1. ing.

  The electrode pads 5 on the semiconductor element 4 are arranged in a plurality of rows along the long side of the semiconductor element 4, and are arranged in the horizontal direction (direction along the long side of the semiconductor element 4) and the vertical direction (of the semiconductor element 4. Large area pads and small area pads are alternately arranged in the direction orthogonal to the long side.

  The semiconductor element 4 having such an electrode pad 5 is mounted on the substrate 1 by conventionally known face-down bonding, and the electrode pad 5 on the semiconductor element 4 and the connection pad 3 on the substrate 1 facing each other are connected. It is electrically connected through the conductive material 6.

  What is important here is that one of the opposing electrode pads 5 and connection pads 3 has a larger pad area than the other, and the relationship between the two pad areas is in accordance with the arrangement of the pads 3 and 5. In order to adopt such a configuration, the large-area electrode pad 5 is opposed to the small-area connection pad 3 and the small-area electrode pad 5 is opposed to the large-area connection pad 3. It is arranged.

  For this reason, the conductive material 6 is alternately arranged in the shape of a trapezoidal cross section that expands toward the connection pad 3 side and the cross-sectional trapezoidal shape that expands toward the electrode pad 5 side. The difference in the contact area between the conductive material 6 and the electrode pad 5 and the contact area between the conductive material 6 and the connection pad 3 can be made smaller than before. Therefore, the difference in bonding strength between the conductive material 6 and the semiconductor element 4 and between the conductive material 6 and the substrate 1 is reduced, and it is satisfactorily prevented that either one of the bonding strengths becomes extremely weak. The bonding strength with 1 can be increased.

  In addition, in this embodiment, since the size relationship of the pad area is alternately reversed in both the vertical and horizontal directions, a difference in bonding strength between the conductive material 6 and the semiconductor element 4 and between the conductive material 6 and the substrate 1 is obtained. Can be made smaller than before.

  The semiconductor element 4 described above first obtains an ingot (lumps) made of single crystal silicon by adopting a conventionally known chocolate ski method, and slices it into a plate shape using a diamond cutter or the like. After that, it is formed by integrating electronic circuits such as switching elements, latches, and shift registers, electrode pads 5 and the like with high density using a conventionally well-known semiconductor manufacturing technique.

  In order to mount the semiconductor element 4 on the substrate 1, when the conductive material 6 is made of solder, first, a solder paste is applied onto the electrode pad 5 of the semiconductor element 4 by a well-known screen printing method. By melting at a predetermined temperature (200 ° C. to 270 ° C.), a substantially spherical solder bump is formed on the electrode pad 5. Next, the semiconductor element 4 is placed at a predetermined position on the upper surface of the substrate so that the electrode pad 5 having a large pad area corresponds to the connection pad 3 having a small pad area, and the electrode pad 5 having a small pad area corresponds to the connection pad 3 having a large pad area. To be placed. Finally, the above-described solder bump is heated and melted, and the mounting operation is completed by electrically and mechanically connecting the electrode pad 5 and the connection pad 3 with the melted solder.

  The semiconductor element 4 and the conductive material 6 are covered with a sealing material 7 made of a bisphenol type epoxy resin.

  The sealing material 7 is for protecting the semiconductor element 4 from corrosion caused by contact with moisture contained in the atmosphere, and the bisphenol type epoxy resin is mainly composed of bisphenol A having an appropriate molecular weight. This can be satisfactorily introduced into the gap between the substrate 1 and the semiconductor element 4 by a capillary phenomenon, whereby the conductive material 6 can be completely covered with the sealing material 7.

  The sealing material 7 is a bisphenol-type epoxy resin varnish applied to a predetermined region on the upper surface of the substrate 1 on which the semiconductor element 4 is mounted using a dispenser or the like, and heated at a temperature of 150 ° C. to 200 ° C. It is formed in a state where the entire semiconductor element is covered by polymerization. At this time, since the varnish of the bisphenol type epoxy resin is satisfactorily introduced into the gap between the semiconductor element 4 and the substrate 1 by the capillary phenomenon as described above, the conductive material 6 is completely covered with the sealing material 7. It becomes. The viscosity of the varnish is preferably set to 100 poises or less, and by making it within this range, the above-described capillary phenomenon can be exhibited better.

  The mounting structure of the present invention is not limited to the above-described embodiment, and various changes and improvements can be made without departing from the gist of the present invention.

  For example, in the above-described embodiment, the connection pad 3 and the electrode pad 5 are formed in a substantially square shape, but may be replaced with a pentagonal shape, a hexagonal shape, a circular shape, or the like.

  In the above-described embodiment, the pad area size relationship is reversed between adjacent pads for all the connection pads 3 and electrode pads 5, but the pads for some of the connection pads 3 and electrode pads 5 are also reversed. It suffices that the size relationship is reversed between adjacent pads. However, the former is preferable in order to achieve the effects of the present invention.

  In the above-described embodiment, an adhesion layer made of a metal such as palladium may be interposed between the connection pad 3 and the circuit conductor 2 in order to increase the adhesion between them.

  Furthermore, in the above-described embodiment, the connection pad 3 is formed of a single metal. Instead, the connection pad 3 is formed of a second connection pad made of gold on a first connection pad made of two or more kinds of metals, for example, nickel. May be used to form a connection pad 3 having a two-layer structure, or a connection pad 3 having a multilayer structure in which three or more kinds of metals are sequentially stacked.

FIG. 1 is a cross-sectional view showing a form in which the mounting structure of the present invention is applied to a thermal head. FIG. 2 is an enlarged view of a main part of the thermal head of FIG. FIG. 3 is a plan view of a semiconductor element mounted on the thermal head of FIG. 1 as viewed from one main surface side.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2 ... Circuit conductor 3 ... Connection pad 4 ... Semiconductor element 5 ... Electrode pad 6 ... Conductive material 7 ... Sealing material R ... Heating element

Claims (3)

A semiconductor device in which a semiconductor element on which a plurality of electrode pads are arranged is arranged on a substrate on which a plurality of connection pads are arranged so that the connection pads and the electrode pads face each other, and both are connected by a conductive material. In the element mounting structure,
Among the electrode pads and the connection pads facing each other, one of the pad areas is made larger than the other, and the magnitude relation between the two pad areas is alternately inverted along the arrangement of the pads. Semiconductor element mounting structure. The semiconductor element mounting structure according to claim 1, wherein the conductive material has a trapezoidal cross section. The electrode pad and the connection pad are arranged in a plurality of rows, and the size relationship between the electrode pad and the connection pad facing each other in adjacent rows is reversed. Mounting structure of semiconductor element.

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