JP2005327914A - Circuit board and mounting method of electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit board, its manufacturing method and a mounting method of electronic components. <P>SOLUTION: The circuit board is constituted, such that material having a conductive layer 2 is prepared for one side of an insulating resin layer 1 of low resistance for resin etching, a circuit wiring pattern 4 is formed in the conductive layer 2 by etching, an adhesive resin layer 5 of high resin etching resistance is stuck to the circuit wiring pattern 4, and a resin projection 7 is formed, by carrying out resin etching of the insulating resin layer 1 of low resin etching resistance. In order to mount a semiconductor device in this circuit board, it is required to prepare a circuit board wherein the resin projection 7 is formed in the vicinity of the electronic-parts connection pad on the circuit board surface, without melting at the solder fusing temperature, and at facedown mounting of the electronic components to a connection pad, the resin projection 7 forms a clearance equal to the height of the resin projection 7 between the circuit board and electronic components. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a circuit board structure, a manufacturing method, and an electronic component mounting method, and more particularly to a circuit board on which a semiconductor device is mounted.

  In recent years, there has been an increasing demand for miniaturization and higher density of mounting boards mounted on electronic devices for small electronic devices such as mobile phones. Along with this, the mounting method of chip components such as IC chips on a substrate is also shifting to a method capable of achieving higher density. In the conventional wire bonding in which mounting is performed face-up, the area required for component mounting is large. Therefore, flip-chip mounting that can be mounted face-down for mounting at higher density is becoming the mainstream mounting method for high-density mounting substrates.

  In flip chip mounting, solder bumps are formed on the IC chip side, mounted on a substrate with a flip chip bonder, and then solder is melted by reflow to obtain connection. The height of the solder bump at this time controls the amount of gap between the IC chip and the connection pad, that is, the height of the IC chip.

  The reason for controlling the height of the IC chip is shown below. Since the thermal expansion coefficient of the IC chip and the mounting board are different, in order to prevent this stress from being applied to the solder and peeling off from the connection pad on the mounting board side, a thermosetting called underfill is used between the IC chip and the mounting board. A step of injecting the functional resin is required. Since this thermosetting resin utilizes capillary action, it is necessary to control the height of the IC chip.

  In particular, lead-free solder, which has become popular in recent years, has a higher reflow temperature than eutectic solder, making it difficult to control the height of the IC chip. According to Patent Document 1, recently, the pitch of solder bumps and connection pads of a mounting board is becoming narrower and lower in height due to the increase in the number of pins of the element. For this reason, the distance between the IC chip and the connection pad is also narrowed, and there is a problem that injection of thermosetting resin is difficult and sometimes impossible, and connection reliability between the IC chip and the mounting substrate may not be ensured. It was.

  With respect to this problem, Patent Document 1 describes that a metal bump that does not melt by reflow is formed on the chip side by plating. Patent Document 2 describes that a metal bump that does not melt by reflow is formed on a connection pad side on the substrate side by plating. However, each of these methods has many man-hours and is complicated, and since plating is performed on the connection pads of the IC chip or the substrate, it is difficult to reduce the pitches of the bumps of the IC chip and the connection pads.

  Further, Patent Document 3 describes that a metal bump that does not melt by reflow is formed by etching on the connection pad side on the substrate side. However, in order to ensure the height of the IC chip, the height of the metal bump is described. That is, since the thickness of the starting material is increased, it is difficult to form the bumps at a narrow pitch, and the method cannot cope with the miniaturization of the connection pads of the substrate.

  FIG. 4 is a process diagram showing a conventional circuit board manufacturing method and chip mounting method for a circuit board. First, as shown in FIG. 4A, a copper foil layer 13 is formed on one surface of an insulating base material 12. A so-called single-sided copper-clad laminate 14 is prepared.

  Next, as shown in FIG. 2 (2), a circuit wiring pattern 5 is formed on the copper foil layer 13 of the single-sided copper clad laminate 14 by using an etching method based on a normal photofabrication method. A circuit board 15 is obtained by providing a solder resist layer as necessary, forming Ni or Au as a surface treatment layer by a method such as electroless plating, and performing external processing by punching with a mold or the like.

  Next, as shown in FIG. 3C, an IC chip 10 having solder bumps 9 is prepared and mounted face-down on the circuit board using a flip chip bonder. Thereafter, reflow is performed to melt the solder balls 9 of the IC chip 10 to obtain a connection between the IC chip 10 and the circuit board 15.

Next, as shown in FIG. 4 (4), the thermosetting resin 11 is injected between the IC chip 10 and the circuit board 15 as an underfill, so that the IC chip 10 is mounted on the circuit board 15 face down.
JP 2001-284380 A JP-A-5-74778 JP 2001-53189 A JP 2003-129259 A JP-A-10-97081

  The distance between electronic components such as IC chips and connection pads is also narrowed, and there is a problem that injection of thermosetting resin is difficult and sometimes impossible. May not be secured.

  With respect to this problem, Patent Document 1 describes that a metal bump that does not melt by reflow is formed on the IC chip side by plating. Patent Document 2 describes that a metal bump that does not melt by reflow is formed on a connection pad side on the substrate side by plating.

  However, each of these methods has many man-hours and is complicated, and since plating is performed on the connection pads of the IC chip or the substrate, it is difficult to reduce the pitches of the bumps of the IC chip and the connection pads. Further, Patent Document 3 describes that a metal bump that does not melt by reflow is formed by etching on the connection pad side on the substrate side. However, in order to ensure the height of the IC chip, the height of the metal bump is described. That is, since the thickness of the starting material is increased, it is difficult to form the bumps at a narrow pitch, and the method cannot cope with the miniaturization of the connection pads of the substrate.

  That is, the problem to be solved by the present invention is to ensure the height of an appropriate electronic component such as an IC chip after mounting the electronic component such as an IC chip and to make the connection pads finer.

  According to the invention for solving the above-mentioned problems, in a method for manufacturing a circuit board, a material having a conductive layer is prepared on one side of an insulating resin layer having a low resistance to a resin etching solution, and a circuit wiring pattern is formed on the conductive layer by etching. And forming a protrusion by bonding an adhesive resin layer having a high resin etching resistance on the circuit wiring pattern and etching the insulating resin layer having a low resin etching resistance. Is adopted.

  Further, according to the invention, when preparing a circuit board having a resin protrusion formed in the vicinity of the electronic component connection pad on the surface of the circuit board that does not melt even at a temperature at which the solder melts, An electronic component mounting method is employed, wherein a gap equal to the height of the resin protrusion is formed between the circuit board and the electronic component by the resin protrusion.

  Furthermore, according to the invention, the circuit board structure is characterized in that the circuit board has a resin protrusion higher than the electronic component connection pad in the vicinity of the electronic component connection pad on the electronic component mounting portion on the surface of the circuit board. .

  Due to these features, the present invention has the following effects.

  A circuit board according to the present invention is prepared by preparing a material having a conductive layer on one side of an insulating resin layer having a low resistance to a resin etching solution, forming a circuit wiring pattern on the conductive layer by etching, and having a resin etching resistance on the circuit wiring pattern. It is manufactured by bonding a high adhesive resin layer and forming a protrusion by resin etching the insulating resin layer having a low resin etching resistance, and when the electronic component is face-down mounted on a connection pad, the resin protrusion Since it is mounted by forming a gap equal to the height of the resin protrusion between the circuit board and the electronic component, the height of the electronic component can be made constant without being affected by the reflow profile, When the electronic component is mounted face down, the resin protrusion is deformed, and the solder bump of the electronic component is melted during reflow. It is also possible to deform the can to improve the fillet shape of the solder balls by being opened.

  Further, since it is not necessary to thicken the plating on the connection pad, not only can the pitch of the connection pad be reduced, but also the connection pad is embedded in the insulating base material, so that the substrate can be made thinner. For this reason, it is possible to provide a fine and high-density mounting circuit board and an inexpensive and stable manner and to mount electronic components at a low cost and stably.

  Hereinafter, the present invention will be further described with reference to the illustrated embodiments.

  FIG. 1 is a process diagram showing a method of manufacturing a circuit board according to the present invention. First, as shown in FIG. 1A, an insulating resin 1 having low resistance to a resin etching solution described in Patent Document 5 is shown. A single-sided copper-clad plate 3 having a copper foil 2 is prepared. Here, the resin etching solution is preferably a solution composed of an alkali metal, an amine compound and water described in Patent Document 5.

  As the kind of the insulating resin 1, a polyimide film obtained by polycondensation of pyromellitic dianhydride and an aromatic diamine (for example, Kapton manufactured by DuPont of the United States, Apical manufactured by Kanae Chemical Co., Ltd.) or a similar structure is used. These thermoplastic polyimides and their precursors are preferred.

  Next, as shown in FIG. 2B, a circuit wiring pattern 4 is formed on the copper foil 2 of the single-sided copper-clad plate 3 by using an etching method based on a normal photofabrication method.

  Next, as shown in FIG. 3C, an insulating resin 5 having a high resistance to a resin etching solution is formed on the circuit wiring pattern 4. Casting, laminating, coating, or the like can be applied as a method for forming the insulating resin 5. An optimum method is selected depending on the type and form (varnish, film) of the insulating resin.

  Here, a thermosetting polyimide film was thermocompression bonded by lamination. The insulating resin 5 having a high resistance to the resin etching solution is an adhesive layer, and an acrylic resin, an epoxy resin, a thermoplastic polyimide, or the like having a higher resistance to the resin etching solution than the insulating resin 1 having a low resistance to the resin etching solution is selected. Is possible. In the case of polyimide, a polyimide film obtained by polycondensation of biphenyltetracarboxylic dianhydride and diaminobenzene (for example, Upilex manufactured by Ube Industries, Ltd.) and a precursor thereof are suitable.

  Next, a resist layer 6 for forming resin protrusions is formed on the insulating resin 1 as shown in FIG.

  Next, as shown in FIG. 5 (5), resin etching is performed to form insulating resin protrusions 7. Only the insulating resin 1 having low resin etching resistance is selectively etched.

  Next, as shown in FIG. 6 (6), the resist layer 6 is peeled off, and a solder resist layer is provided if necessary, or Ni or Au is used as a surface treatment layer by a method such as electroless plating, External processing is performed by punching or the like to obtain the circuit board 8. Although not shown in the drawing, a double-sided board can be formed by via hole connection or the like by a conventional method.

  FIG. 2 is a process diagram showing a method for mounting an electronic component according to the present invention. First, as shown in FIG. 2A, an IC chip 10 having solder bumps 9 is prepared and a flip chip bonder is used. Then, face-down mounting is performed on the circuit board 8 manufactured in the process shown in FIG. Thereafter, reflow is performed to melt the solder balls 9 of the IC chip 10 to obtain a connection between the IC chip 10 and the circuit board 8. At this time, the height of the IC chip is defined by the resin protrusions 7 on the circuit board 8, and a solder fillet shape can be obtained.

  Next, as shown in FIG. 2B, the thermosetting resin 11 is injected between the IC chip 10 and the circuit board 8 as an underfill so that the IC chip 10 is mounted face-down on the circuit board 8.

  FIG. 3 is a conceptual cross-sectional view showing the structure of the circuit board of the present invention, which is a circuit board 8 having a resin protrusion 7 that defines the height of the IC chip as shown in FIG. The circuit wiring pattern 4 has a structure embedded in the insulating layer 5. The height of the IC chip 10 from the circuit board 8 when the IC chip 10 is face-down mounted on the circuit board 8 as shown in FIG.

Process drawing which shows the manufacturing method of the circuit board of this invention. Process drawing which shows the mounting method of the electronic component of this invention. 1 is a conceptual cross-sectional configuration diagram illustrating a structure of a circuit board according to the present invention. Process drawing which shows the manufacturing method of the circuit board by the conventional method, and the mounting method of an electronic component.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Insulation resin with low resin etching resistance 2 Copper foil 3 Single-sided copper-clad board 4 Circuit wiring pattern 5 Insulation resin with high resistance to resin etching solution 6 Resist layer 7 Resin protrusion 8 Circuit board 9 according to the present invention Solder bump 10 IC chip 11 Thermosetting Resin 12 Insulating base material 13 Copper foil layer 14 Single-sided copper-clad board 15 Circuit board by conventional method

Claims (3)

  In a circuit board manufacturing method, a material having a conductive layer is prepared on one side of an insulating resin layer having a low resin etchant resistance, a circuit wiring pattern is formed by etching on the conductive layer, and the resin etching resistance is formed on the circuit wiring pattern. A method of manufacturing a circuit board, comprising: bonding a high adhesive resin layer and etching the insulating resin layer having low resin etching resistance to form a protrusion.   A circuit board having a resin protrusion that is not melted even at a temperature at which solder is melted on the surface of the circuit board is prepared in the vicinity of the electronic component connection pad, and when the electronic component is face-down mounted on the connection pad, the resin protrusion A method of mounting a semiconductor device, wherein a gap equal to the height of a resin protrusion is formed between the electronic components.   A circuit board having a resin protrusion higher than an electronic component connection pad on an electronic component mounting portion on the surface of the circuit board in the vicinity of the electronic component connection pad.

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