JP4483455B2 - Manufacturing method of circuit board for mounting semiconductor element - Google Patents

Description

  The present invention relates to a method of manufacturing a circuit board for mounting a semiconductor element, which is a component such as a mobile phone, a home appliance, and various sensors.

  2. Description of the Related Art Conventionally, a circuit board for mounting a semiconductor element is generally manufactured by putting a filler in a base material resin in order to reduce a difference in coefficient of linear expansion from the semiconductor element. Here, there are spherical and fibrous fillers, and the latter is often used because it has a higher effect of suppressing thermal expansion.

  However, when the gate position is set as shown in FIG. 12A, when the fibrous filler 25 is mixed with the base resin and used, a circuit board for mounting a semiconductor element (hereinafter referred to as a molded product 16) before circuit formation is used. The fibrous filler 25 is easily oriented in the flow direction of the molding resin (the direction from the upper right to the lower left in FIG. 12A). In this case, as shown in FIG. 12B, in the EE cross section in FIG. 12A, the cross-sectional direction of the fibrous filler 25 is aligned, and the effect of suppressing thermal expansion is reduced. Therefore, as shown in FIG. 12C, when a thermal load at the time of mounting or a temperature change at the time of use is applied to the circuit board 26 for mounting the semiconductor element, the mounting joint portion in the direction along the cross section is broken. There is a case.

  By the way, as a technique for controlling the orientation of the fibrous filler, there are a technique disclosed in JP 2001-81202 A and a technique disclosed in JP 2001-106799 A. These are oriented in any one direction by adding a magnetic field for the orientation of polybenzazole short fibers and aramid fibers mixed in the resin resin for conductor circuits and the molding resin of the polymer composite material molded product. Both are techniques for improving specific physical properties such as the resin circuit board for conductor circuits, and for aligning the filler in the substrate in a predetermined direction. Regarding a method for applying to a circuit board for mounting semiconductor elements, Not mentioned.

JP 2001-81202 A JP 2001-106799 A

  The present invention has been invented in view of the above-described background art, and the problem is that in the method of manufacturing a circuit board for mounting a semiconductor element that uses a fibrous filler, the orientation of the fibrous filler is controlled and mounted. It is to provide a method for manufacturing a circuit board for mounting a semiconductor element in which a mounting joint portion is not broken due to a thermal load of the device or a temperature change during use.

  In order to solve the above problems, the present invention provides a resin injection step of injecting a molding resin containing a fibrous filler that is a magnetic material into a cavity in a mold, and a molded product that overlaps at least a semiconductor element to be mounted. A circuit board for mounting a semiconductor element, comprising: a magnetic field application step for applying a magnetic field in a direction intersecting a flow direction of the molding resin to a cavity corresponding to the portion; and a resin curing step for curing the molding resin for the cavity. It is a manufacturing method.

  According to the present invention, in the circuit board for mounting semiconductor elements, since the fibrous filler that is a magnetic material can be oriented in the direction intersecting with the flow direction of the molding resin, mounting is also performed in the direction intersecting with the flow direction. It is possible to manufacture a substrate that is resistant to heat history such as heat load during use and temperature change during use.

  FIGS. 1-8 has shown the manufacturing method of the circuit board for semiconductor element mounting which is 1st embodiment corresponding to all Claims 1-5 of this application. In the method of manufacturing a circuit board for mounting a semiconductor element according to this embodiment, as shown in FIGS. 2 and 3, resin injection for injecting a molding resin 11 containing a fibrous filler that is a magnetic material into a cavity 7 in a mold 2. 4 and a magnetic field adding step of applying a magnetic field in a direction intersecting the flow direction of the molding resin 11 to the cavity corresponding to the portion of the molded product that overlaps at least the semiconductor element to be mounted, and as shown in FIG. And a resin curing step of curing the cavity molding resin 11.

  Hereinafter, the first embodiment of the method for manufacturing a substrate for a semiconductor element mounting circuit according to this embodiment is divided into a manufacturing method of a molding resin, a resin injection process, a magnetic field application process, a resin curing process, and other processes, and more specifically. This will be described in detail.

  First, a method for producing a molding resin will be described. The fibrous filler, which is a magnetic material, was cast iron having an outer diameter of 30 μm and a length of 250 μm, and its surface was coated with polyimide so that the film thickness was about 5 to 15 μm by dipping. This was put in a barrel shape and heated while rotating to dry and harden while avoiding sticking of fibrous fillers that are magnetic materials. This was mixed with polyphthalamide (trade name: N1000, manufactured by Kuraray Co., Ltd.), which is a base resin, and 50% by weight was mixed sufficiently with a heating roll to produce a molding resin.

  Here, the mixing ratio of the fibrous filler, which is a magnetic material, is preferably in the range of 20 to 70 wt%. If this range is exceeded, the effect of suppressing the desired thermal expansion may not be obtained, or the viscosity of the molding resin may be excessive and the productivity in the resin injection process may be reduced. On the other hand, below this range, the effect of preventing thermal expansion cannot be sufficiently obtained.

  Next, the resin injection process will be described. 2 and 3, the nozzle 3 of the injection cylinder is brought into contact with the mold 2 and the molding resin 11 is injected under the conditions of a resin temperature of 330 ° C., a mold temperature of 140 ° C., and an injection speed of 50 mm / s. It was carried out. Here, the mold 2 is shown in FIG. 1. As shown in FIG. 1, the central and outer yokes are exposed to the cavity in the fixed mold 5 using a non-magnetic high-strength aluminum alloy as a mold material. After the electromagnet 4 was provided, the mold 2 was constructed by combining with a movable mold 6 using a non-magnetic high-strength aluminum alloy as a mold material. Here, the gate position 1 is the corner of the mold cavity.

  In addition, as shown in FIG. 6, the electromagnet 4 is made of hardened carbon steel, and the winding direction of the coil 8 and the direction of current flow are set so that the central part is the N pole 10 and the outer peripheral part is the S pole 9. Set. The coil 8 was obtained by winding an enameled copper wire on a yoke with an insulating sheet containing mica generally used for the coil. In FIG. 6B, the bottom surfaces of the downward projecting portions of the N pole 10 and the S pole 9 are made substantially flush.

  Next, the magnetic field application process will be described. As shown in FIGS. 2 and 3, these were performed by applying a magnetic field of 350 A / m radially from the approximate center of the cavity simultaneously with the injection. The magnetic field at this time is preferably in the range of 200 to 500 A / m. If it is less than 200 A / m, the fibrous filler that is a magnetic substance cannot be sufficiently oriented, and if it exceeds 500 A / m, heat generation of the coil 2 is inevitable. In FIG. 6B, the bottom surfaces of the downward projecting portions of the N pole 10 and the S pole 9 are substantially flush, so that the magnetic field is not applied to the entire cavity. Only the planar portion (hatched portion) 13 excluding the portion 14 is radially added.

  Next, the resin curing step and other steps will be described. This was carried out by cooling the molding resin 11 as shown in FIG. When curing of the molding resin is completed, the current supply to the electromagnet 4 is stopped, the mold 2 is opened, and the molded product 16 is integrated with the gate portion 17 by protruding with an ejector pin (not shown). Released. Then, as shown in FIG. 5, the gate part 17 was cut | disconnected and the desired molded article 16 was obtained. Then, a circuit board was formed on the surface of the molded product using a circuit patterning method such as a laser patterning method, a mask exposure method, or a two-shot method, to obtain a circuit board for mounting a semiconductor element. And after flip-chip mounting a semiconductor element on this circuit board, an underfill resin was injected and cured to obtain a semiconductor element mounting package.

  Here, the molding resin is obtained by kneading a fibrous filler that is a magnetic material and a base material resin, and is a concept that includes both a thermoplastic resin and a thermosetting resin.

  The part 24 of the molded product that overlaps the semiconductor element 21 mounted here is hidden by the semiconductor element 21 when the molded product 16 is observed from the upper part in a state where the semiconductor element 21 is mounted as shown in FIG. This refers to the surface portion of the molded product 16 that faces the semiconductor element 21.

  According to the first embodiment, in the circuit board for mounting a semiconductor element, the fibrous filler that is a magnetic material can be oriented in the direction intersecting with the flow direction of the molding resin, and therefore the direction intersecting with the flow direction. In this case, it is possible to manufacture a substrate that is resistant to heat history such as heat load during mounting and temperature change during use.

  Further, according to the first embodiment, as shown in FIG. 1, in the resin injection process, the molding resin is injected from the outer peripheral portion of the cavity of the flat plate mold so that the gate position 1 is the corner of the cavity. By doing so, as shown in FIG. 3, the flow direction of the molding resin 11 is likely to be substantially parallel. Therefore, the orientation of the fibrous filler that is a magnetic material can be easily achieved by applying a magnetic field in a direction perpendicular thereto. It can be suppressed, and can be controlled by ordinary injection molding, so-called multi-cavity (molding method to obtain a plurality of molded products by injecting molding resin from one injection cylinder to a plurality of molds) It is preferable in that it can be applied.

  Further, according to the first embodiment, as shown in FIG. 7, the magnetic field is applied only to the plane portion (hatch portion) 13 except for the protruding portion 14 of the cavity instead of the entire cavity. When the magnetic field is applied only to the plane including the surface to be processed, the density of the fibrous filler, which is a magnetic material, increases at the site where the magnetic field is applied, so that the strength of the plane portion increases and the connection reliability after mounting It is suitable in terms of enhancing the properties. In addition, it is not necessary to fill the protruding portion 14 of the cavity that is not the mounting portion of the semiconductor element with a fibrous filler that is a magnetic body, and the mixing rate of the fibrous filler that is a magnetic body into the molding resin can be reduced, so that injection molding is performed. It is also preferable in that the pressure at the time can be lowered.

  Further, according to the manufacturing method of the first embodiment, in the magnetic field application step, as shown in FIG. 2, the magnetic field is applied radially from the approximate center of the cavity, so that the molded product 16 as shown in FIG. In FIG. 8, the fibrous filler 18 that is a magnetic material is oriented radially from the approximate center of the molded product 16, not in the flow direction of the molding resin (the direction from the upper right to the lower left in FIG. 8A). In this case, as shown in FIG. 8B, in any cross section passing through the center of the portion of the molded product 16 that overlaps the semiconductor element, such as the DD cross section in FIG. The longitudinal direction of the filler 18 is aligned in the cross section, which is preferable in that the effect of suppressing thermal expansion is further enhanced.

  Further, according to the manufacturing method of the first embodiment, since the iron-based fibrous filler is used as the fibrous filler that is a magnetic material, it can be oriented with a relatively low magnetic field, and the cost of the raw material can be kept low. This is preferable in that it can be performed.

  FIG. 11 shows a second embodiment of the present invention. In the resin injection process of the first embodiment, the vibration is applied by the vibrator 29 via the vibration direction changer 28 installed immediately below the nozzle 3 of the injection cylinder, so that the vibration and the magnetic field are superimposed and added. Others are the same as in the first embodiment. This facilitates the orientation of the fibrous filler that is a magnetic material, reduces the magnetic field applied during the magnetic field application step, and enables downsizing of the manufacturing apparatus.

  In the above embodiment, as shown in FIG. 2, a magnetic field is applied radially from the approximate center of the cavity. However, the magnetic field is applied radially from the approximate center of the cavity corresponding to the portion of the molded product that overlaps the semiconductor element mounted in this way. Any magnetic field can be applied as long as the direction intersects the flow direction of the molding resin 11 without being limited to the application of the magnetic field. For example, a magnetic field may be applied concentrically from the center, or a magnetic field may be applied in a direction substantially orthogonal to the flow direction.

  Furthermore, although the fibrous filler which is a magnetic body is cast iron, iron, iron-silicon alloy, iron-aluminum alloy, iron-silicon-aluminum alloy, nickel-iron alloy, cobalt-iron alloy, manganese-zinc Examples thereof include nickel ferrite and nickel-zinc ferrite. The material is not limited to an inorganic material as long as it is oriented in response to a magnetic field, and for example, graphitized carbon fiber, polybenzazole short fiber, aramid short fiber, and the like can be used.

  Moreover, although it is a dimension of a magnetic body fibrous filler, if a shape is fibrous form, arbitrary things can be used and the thing in the range of 5-200 micrometers outer shape and 50-800 micrometers in length can be illustrated. In particular, those having an outer diameter of 20 to 50 μm and a length of 200 to 300 μm are preferable because the material can be easily produced as fibrous chips by chattering vibration cutting on a lathe.

  In addition, although the polyimide is dipped on the surface of the fibrous filler that is a magnetic material, a resin such as polyparaxylylene and epoxy can be used in addition to polyimide as long as the surface can be electrically insulated. . This insulation treatment can further reduce the electrical conductivity of the molded product, and improves the electrical insulation reliability as a circuit board, which is preferable. In addition to dipping, a coating method such as coating or vapor deposition polymerization can be used.

  In the first embodiment, the base resin for molding is polyphthalamide, but heat such as phenol resin, unsaturated polyester resin, epoxy resin, bismaleimide resin, benzocyclobutene resin, diallyl phthalate resin, urethane resin, etc. Examples thereof include thermoplastic resins such as curable resins, liquid crystal polymers typified by wholly aromatic polyesters, polyphenylene ether, polysulfone, polyether sulfone, polyphenylene sulfide, polyimide, and polyvinylidene fluoride. Polyphthalamide is preferred from the balance of various properties such as heat resistance, mechanical properties, moldability, etc., and liquid crystal polymers typified by omnidirectional polyesters are easy to control orientation because they are easily polarized by a magnetic field. Polyimide, polyphenylene sulfide, and polyvinylidene fluoride are preferable.

  Furthermore, the fibrous filler is not limited to a single material, and may be a mixture of a plurality of types, for example, a fibrous filler that is a magnetic material and a non-magnetic fiber filler such as glass fiber. For example, a method of manufacturing a circuit board for mounting a semiconductor element by mixing 30% by volume of cast iron and glass fiber having substantially the same shape as this and manufacturing the circuit board for mounting a semiconductor element according to the same procedure as that of the first embodiment is also a technical idea of the present invention. include.

  In this case, as shown in FIG. 10, the fibrous filler 18 that is a magnetic material is oriented radially from the approximate center of the portion that overlaps the semiconductor element to be mounted, and the non-magnetic fibrous filler (thin wire) 27 is The resin flows in the direction of flow (from the upper right to the lower left in FIG. 10). When viewed as a whole, the fibrous filler 18 of the magnetic material and the fibrous filler (thin wire) 27 of the nonmagnetic material cross. It takes a shape that is oriented. This makes it possible to control the fibrous filler in multiple directions, which is preferable.

It is drawing which shows the manufacturing method of the circuit board for semiconductor element mounting which is 1st embodiment of this invention, (a) is BB sectional drawing, (b) has shown AA sectional drawing, respectively. It is drawing which shows the manufacturing method of the circuit board for semiconductor element mounting which is 1st embodiment of this invention, (a) is BB sectional drawing, (b) has shown AA sectional drawing, respectively. It is drawing which shows the manufacturing method of the circuit board for semiconductor element mounting which is 1st embodiment of this invention, (a) is BB sectional drawing, (b) has shown AA sectional drawing, respectively. It is drawing which shows the manufacturing method of the circuit board for semiconductor element mounting which is 1st embodiment of this invention, (a) is BB sectional drawing, (b) has shown AA sectional drawing, respectively. The side view of the molded product and gate part which are 1st embodiment of this invention. It is drawing which shows the electromagnet used for 1st embodiment of this invention, (a) is a top view, (b) has each shown CC sectional drawing of (a). It is drawing which shows the part (hatch part) which added magnetization in the cavity which is 1st embodiment of this invention, (a) shows BB sectional drawing, (b) shows AA sectional drawing, respectively. ing. BRIEF DESCRIPTION OF THE DRAWINGS It is drawing which shows the molded article or semiconductor element mounting package obtained with the manufacturing method of the circuit board for semiconductor element mounting which is 1st embodiment of this invention, (a) is a top view of a molded article, (b) is shaping | molding. DD sectional drawing of goods, (c) has each shown DD sectional drawing of the semiconductor element mounting package. The perspective view of "the part of the molded article which overlaps with the semiconductor element mounted" in this invention. The top view of the molded product at the time of mixing the filler which is a magnetic body which is 1st embodiment of this invention, and the filler which is a nonmagnetic body. Sectional drawing which shows the manufacturing method of the circuit board for semiconductor element mounting which is 2nd embodiment of this invention. It is drawing which shows the molded article or semiconductor element mounting package obtained with the manufacturing method of the circuit board for semiconductor element mounting which is one Embodiment of the conventional invention, (a) is a top view of a molded article, (b) is molding EE sectional drawing of goods, (c) has each shown EE sectional drawing of a semiconductor element mounting package.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Gate position 2 Mold 7 Cavity 11 Molding resin 12 Arrow which shows the direction of the added magnetic field 13 Plane part (hatch part) except the protrusion part of a cavity
14 Cavity protrusion 15 Arrow 16 representing flow direction of resin for molding 16 Molded product 18 Fibrous filler 19 as magnetic material Arrow 20 indicating gate position Solder 21 Semiconductor element 24 Part 25 of molded product overlapping with semiconductor element to be mounted Fibrous filler 26 Circuit board 27 for mounting semiconductor elements Fibrous filler that is a non-magnetic material (thin wire)
30 Electrical Circuit 31 Semiconductor Device Mounting Package

Claims (5)

  Resin molding process for injecting molding resin containing fibrous filler, which is a magnetic material, into the cavity in the mold, and at least for the cavity corresponding to the part of the molded product that overlaps the semiconductor element to be mounted A method of manufacturing a circuit board for mounting a semiconductor element, comprising: a magnetic field applying step for applying a magnetic field in a direction crossing the flow direction of the resin; and a resin curing step for curing the resin for molding the cavity.   2. The method of manufacturing a circuit board for mounting a semiconductor element according to claim 1, wherein the resin injection step is a step of injecting a molding resin from an outer peripheral portion of the cavity in the flat plate mold.   3. The method of manufacturing a circuit board for mounting a semiconductor element according to claim 1, wherein the magnetic field applying step applies a magnetic field only to a plane including a surface on which the semiconductor element is mounted. .   The magnetic field applying step adds a magnetic field radially from substantially the center of the cavity corresponding to the part of the molded product that overlaps the semiconductor element to be mounted. A method of manufacturing a circuit board for mounting a semiconductor element.   The method for producing a circuit board for mounting a semiconductor element according to any one of claims 1 to 4, wherein the fibrous filler which is a magnetic substance is an iron-based fibrous filler.

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