JP2007013208A - Method for manufacturing printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing printed wiring boards by which no migration is caused. <P>SOLUTION: With regard to a so-called piercing method for manufacturing multilayer boards, almost conical conductor bumps 2 are placed by a press in a prepreg of a substrate of insulating material, and then are hardened for obtaining an electrical conduction in the direction of thickness of the substrate. Wiring patterns are provided on one side of a substrate 3 of non-hardened insulating material, an electrical conduction is obtained in the direction of thickness of the substrate with conductor bumps in the substrate, then a plurality of such substrate units are layered, and the prepregs of the substrates are hardened by heat at a time. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a method for manufacturing a printed wiring board constituting a so-called multilayer board.

  Conventionally, as a method of forming a multilayer board, a prepreg, that is, an uncured insulating material substrate made of a sheet-like thermosetting resin such as an epoxy resin, and a conductive material such as metal powder dispersed in the resin There is a method in which a conductor layer in which conductor bumps are formed in a substantially conical shape is pressed to allow the conductor bumps to penetrate through the prepreg, thereby forming electrical conduction in the thickness direction of the insulating material substrate.

  FIG. 10 is a diagram schematically showing a method of forming an electrical continuity of an insulating material substrate by penetrating a conductor bump (hereinafter, this method is simply referred to as “penetration method”).

  As shown in FIG. 10, in this penetration method, a plurality of substantially conical conductor bumps 102, 102,... Are formed on the first conductor layer 101, and above the conductor bumps 102, 102,. An insulating material substrate prepreg 103 is disposed (FIG. 10A). After that, the first conductor layer 101 and the prepreg 103 are pressed, and the conductor bumps 102, 102,... In this state, the prepreg 103 is cured by heating or the like.

  Next, a second conductor layer 104 is formed on the upper surface of the prepreg 103 in the drawing, and a basic element of a printed wiring board called a “core material” in which a conductor layer is formed on both sides of an insulating material substrate is formed. The

  By the way, in order to form a multilayer board, a pattern is formed on the conductor layer of such a core material, and then 1. 1. Formation of conductor bumps 2. Arrangement of insulating material substrate prepreg; 3. heat curing; 4. Formation of conductor layer A series of operations such as pattern formation and further formation of conductor bumps are repeated to stack one layer at a time. That is, the above operations 1 to 5 are repeated every time one layer is stacked.

  However, since the core material and the inner layer around the core material are repeatedly heated, the insulating material of the inner layer deteriorates due to repeated heating during the multilayering of the outer layer, and the insulating layer is likely to crack. There is a problem. If a crack occurs in the insulating layer, it causes a trouble such as migration, which is a fatal defect.

  The present invention has been made to solve the above problems. That is, an object of the present invention is to provide a method of manufacturing a printed wiring board that does not cause migration.

  In order to solve the above problems, the present invention includes a step of forming a plurality of substantially conical conductor bumps on a conductor plate, a step of disposing an uncured insulating material substrate on the conductor bumps, and the insulation. A step of pressurizing the conductive plate and the insulating material substrate at a temperature at which the material substrate does not harden and penetrating the conductive bump; and patterning the conductive plate to provide a predetermined wiring pattern, wherein the conductive bump is the insulating substrate Forming a substrate unit penetrating through the substrate, forming a multilayer plate precursor by stacking a plurality of substrate units each having the uncured insulating material substrate, and heating the multilayer plate precursor under pressure. Curing the multilayer precursor.

  In the said invention, although the temperature which the said insulating material board | substrate does not harden | determine depends on the kind of the said insulating material, 115-150 degreeC is mentioned, for example.

  In addition, it is desirable that the pressurization through the conductor plate and the buffer material of the insulating material substrate is performed so that the tip end of the conductor bump is flat and the top surface diameter is on average 50% or more of the bottom surface diameter.

  Furthermore, it is desirable that the patterning of the conductor plate is a step of patterning the conductor plate and the insulating material substrate in a state of being wrapped with a film.

  In another printed wiring board manufacturing method of the present invention, a wiring pattern is provided on each of the first surface and the second surface of the cured insulating material substrate, and the first surface and the second surface are provided. A step of forming a core material containing a conductor bump for electrically connecting the formed wiring patterns; a step of forming a plurality of substantially conical conductor bumps on the conductor plate; and an uncured portion on the conductor bump. A step of disposing the insulating material substrate, a step of pressurizing the conductive plate and the insulating material substrate at a temperature at which the insulating material substrate is not cured, and penetrating the conductive bump, and patterning the conductive plate to obtain a predetermined value. A step of forming a substrate unit including the wiring pattern, wherein the conductive bump penetrates the insulating substrate, and at least one substrate unit having the uncured insulating material substrate, Comprising forming a multi-layer plate precursor was stacked on the surface, and curing said multi-layer plate precursor by heating the multilayer plate precursor under pressure.

  In the present invention, as the step of forming the core material, a step of forming a substantially conical conductor bump on the first conductor plate, and an uncured insulating material substrate are disposed on the leading end side of the conductor bump. A step of pressurizing the first conductive plate and the insulating material substrate to penetrate the conductive bumps through the insulating material substrate; and a second surface of the insulating material substrate through which the tip of the conductive bumps penetrates. A step of disposing a conductive plate, a step of heating the first conductive plate and the second conductive plate under pressure to cure the insulating material substrate, and patterning the first conductive plate. And a step of forming a pattern on the second conductive plate.

  Moreover, as an insulating material board | substrate used for the said core material, it is preferable to use what is comprised from the resin composition hardened | cured completely by two times of heating.

  In the method for manufacturing a printed wiring board according to the present invention, a plurality of patterned substrate units are stacked on an uncured insulating material substrate, and then heated and cured at a time. No heating is applied. Therefore, the deterioration due to repeated heating is eliminated, and the occurrence of cracks and the migration caused by the cracks can be prevented.

  Further, since the heating process is only required once, the manufacturing process can be simplified and the manufacturing cost can be reduced.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the printed wiring board which does not produce a migration can be provided.

  (First Embodiment) A method for manufacturing a printed wiring board according to an embodiment of the present invention will be described below. 1 to 4 are vertical sectional views schematically showing the procedure for manufacturing the printed wiring board according to this embodiment, and FIG. 5 is a flowchart showing the procedure.

  First, as shown in FIG. 1, a substrate unit, that is, one in which a wiring pattern is formed on one surface of an uncured insulating material substrate, and a conductor bump for forming electrical conduction in the thickness direction of the insulating material substrate is built in. Form.

  As shown in FIG. 1A, a thin plate-like conductor, for example, a conductor plate 1 such as a copper foil is prepared (STEP 1), and a plurality of substantially conical shapes are formed on the conductor plate 1 along a predetermined circuit pattern. Conductor bumps 2, 2,... Are formed using a printing technique or the like (FIG. 1 (a) / STEP2). Thereafter, an uncured insulating material substrate (prepreg) 3 is placed on the conductor bumps 2, 2,... (FIG. 1B / STEP3). As the insulating material substrate 3 used here, a glass fiber sheet impregnated with a widely used epoxy resin, or a material having a glass transition temperature of 170 ° C. or higher, for example, a bismaleide triazine resin or the like can be used.

  Here, the reason for adopting a material having a glass transition temperature of 170 ° C. or higher is that, generally, a material having a higher glass transition temperature has a smaller material thermal expansion coefficient between the glass transition temperature and the thermal expansion coefficient. This is because the higher the glass transition temperature, the better the heat resistance.

  Moreover, the value of the glass transition temperature is set to 170 ° C. or more. If the glass transition temperature is less than 170 ° C., the thermal expansion coefficient of the material becomes larger than a certain limit, and the conductive bump and the insulating material substrate This is because a mismatch occurs between the conductor bumps and a crack is generated in the conductor bump in the solder heat resistance test (left at 288 ° C. for 10 seconds), resulting in an adverse effect that the electrical connection is broken.

  Next, the conductor plate 1 and the insulating material substrate 3 are pressed through an elastic material (not shown) to press the conductor plate 1 and the insulating material substrate 3, and the conductor bumps 2, 2 are applied to the insulating material substrate 3. ,... Are penetrated (FIG. 1 (c) / STEP4).

  The tip side of the conductor bumps 2, 2,... Is flattened by performing pressing at this time under predetermined conditions. As a result, the conductor bumps 2, 2,... Are deformed into a shape having a substantially trapezoidal vertical cross section, as shown in a partially enlarged view of the circled portion in FIG. The shape of the conductor bump 2 after deformation is preferably such that the upper surface diameter R2 is 50% or more of the lower surface diameter R1 on average.

  Here, with respect to the preferable cross-sectional shape of the conductor bump 2 after deformation, the top surface diameter R2 is 50% or more of the bottom surface diameter R1 on average, and when R2 is less than 50% of R1, as shown in FIGS. Since the contact area of the bump upper surface when it is laminated and pressed after passing through the bump is very small, an allowable electric capacity (current value that can be passed) is limited, and the conduction resistance value is reduced in the diameter of the bump upper surface. This is because it causes an adverse effect that the electrical connection reliability decreases with the increase.

  Next, after forming a photoresist material layer (not shown) on the conductor plate 1 of this substrate unit, it is covered and protected by a light-transmitting protective film 4 (STEP 5).

  The reason why the substrate unit is covered with the protective film 4 is to protect the insulating material substrate 1 and the conductor bumps 2, 2,. A pattern is formed on the conductor plate 1 of the substrate unit covered with the protective film 4 (STEP 6). That is, a predetermined wiring pattern is formed by exposing a photoresist material layer on the conductor plate 1 through a mask (not shown) having a predetermined mask pattern, and then etching to remove unnecessary conductor portions. To do.

  FIG. 1E is a vertical sectional view of the substrate unit 5 thus formed. As shown in FIG. 1 (e), in this substrate unit 5, wiring patterns 1a, 1a,... Are formed on the lower surface side of the uncured insulating material substrate 3 in the figure, and these wiring patterns 1a, 1a,. Are electrically connected to 2, 2,..., And the ends of the conductor bumps 2, 2,.

  A predetermined number of substrate units, for example, five, are created by the same method. FIG. 2 is a view showing a vertical section of the substrate units 5 to 9 constituting the multilayer board. As shown in FIG. 2, a predetermined wiring pattern is formed on each of these substrate units 5 to 9, and each wiring pattern is electrically connected in the thickness direction of the multilayer board by a conductor bump. It is like that. These substrate units 5 to 9 and the conductor plate 10 are laminated in a state where their positional relationships are arranged at appropriate positions as shown in FIG. 2 (STEP 7).

  In this state, the substrate units 5 to 9 and the conductor plate 10 are pressed in the thickness direction of the substrate (STEP 8) to form a multilayer structure, and the insulating material substrate of the substrate units 5 to 9 is cured by heating or the like (FIG. 3). / STEP 9).

  Next, each of the uppermost conductor plate 10 and the lowermost conductor plate 9a is subjected to etching or the like to form a pattern (STEP 10), thereby obtaining a multilayer board as shown in FIG.

  As described above in detail, in the printed wiring board manufacturing method of the present embodiment, the wiring pattern is electrically connected to the wiring pattern on the prepreg of the insulating material board, and the thickness of the insulating material board is electrically connected. The substrate unit including the conductor bumps for forming the substrate is formed in advance, and a plurality of substrate units are stacked and heated under pressure to cure the prepreg. Since the insulating material substrate to be provided is not repeatedly heated by being repeatedly heated, generation of cracks due to the excessive heating and occurrence of migration caused by the cracks can be prevented in advance. Further, in the printed wiring board manufacturing method of the present invention, since a plurality of board units are stacked and then heat-cured at once, the heat-curing process can be performed only once, the manufacturing process can be shortened and the manufacturing cost can be shortened. Can be kept inexpensive.

  Note that this embodiment and the following embodiments do not limit the scope of the present invention.

  Example As shown in FIG. 1A of the first embodiment, a substantially conical conductor bump 2 having a diameter of 0.2 mm was formed on a copper foil 1 having a thickness of 18 μm by a printing technique. Next, as shown in FIG. 1 (b), a BT resin material (registered trademark / manufactured by Mitsubishi Gas Chemical Co., Ltd., model name: GHPL830, thickness 0.06 mm) is stacked as shown in FIG. A substrate unit (copper foil with an insulating material) was formed by penetrating the bumps 2 in the thickness direction of the insulating material. The substrate unit was pressurized to make the tip of the substantially conical conductor bump 2 flat as shown in FIG. At this time, the insulating material is not cured and is in a so-called B stage state. This substrate unit was laminated with a resist film 4, exposed and developed through a predetermined mask pattern, and the copper foil was etched to obtain a substrate unit on which a wiring pattern was formed. Similarly, four board units are prepared and laminated together with the copper foil 10 as shown in FIG. 2, and each board unit is positioned by recognizing one of the conductor bumps as a metal target for positioning with X-rays. A multilayer board having a six-layer structure according to the present invention was obtained by curing the resin of the insulating material by performing a lamination press at 190 ° C. for about 2 hours.

  When the glass transition temperature of the multilayer board thus prepared was measured, it was about 200 ° C., and the original characteristics of the material were obtained. Moreover, since the number of presses between the materials in the multilayer board was one, there was no deterioration of the substrate, the adhesion between the materials was large, and a good value in the drop test was obtained. Furthermore, the migration resistance of the test in which a voltage was applied at high temperature and high humidity was also improved. In addition, since the number of laminations is one, the lead time can be reduced, and the deviation between the substrate units can be eliminated.

  (Second Embodiment) A method for manufacturing a printed wiring board according to a second embodiment of the present invention will be described below. In the present embodiment, the description of the same parts as those in the first embodiment is omitted.

  In the method for manufacturing a printed wiring board according to the present embodiment, a cured substrate unit is used only for a so-called core material disposed at the center of a multilayer board, and the plurality of substrate units stacked on both sides thereof are the above As in the first embodiment, an uncured substrate unit is used.

  6 to 8 are vertical sectional views showing the procedure of the printed defeat board manufacturing method according to this embodiment, and FIG. 9 is a flowchart showing the procedure.

  First, as shown in FIG. 6, a core material, that is, a substrate provided with a conductor layer on both surfaces of an insulating material substrate is prepared. As shown in FIG. 6A, a thin plate-like conductor, for example, a thin plate-like conductor plate 11 such as a copper foil, is prepared (STEP 1), and a plurality of approximate shapes are formed on the conductor plate 1 along a predetermined circuit pattern. The conical conductor bumps (first conductor bumps) 12, 12,... Are formed using a printing technique or the like (FIG. 6A / STEP2). Thereafter, an uncured insulating material substrate (prepreg) 13 is disposed on the conductor bumps 12, 12,... (FIG. 6B / STEP3).

  Next, the conductor plate 11 and the insulating material substrate 13 are pressed through an elastic body (not shown) to allow the conductor bumps 12, 12,... To penetrate the insulating material substrate 13 (FIG. 6C / STEP4). .

  Further, a metal plate, for example, a copper foil 14 as a second conductor plate is pressed and attached to the surface of the insulating material substrate 13 through which the tips of the conductor bumps 12, 12,... Penetrate, that is, the surface 13a in FIG. (D) / STEP5). The core material 15 is completed by curing the insulating material substrate 13 by heating at the same time as or after the pressing (FIG. 6 (e) / STEP 6).

  Next, a wiring pattern is formed on each of the first surface (upper surface in the drawing) and the second surface (lower surface in the drawing) of the core material 15 to obtain a core material having wiring patterns on both surfaces. (FIG. 6 (f) / STEP7).

  On the other hand, as shown in FIG. 7, a wiring pattern is provided on one side of an uncured insulating material substrate in the same manner as described in the first embodiment, and the side opposite to the wiring pattern is provided by a built-in conductor bump. A plurality of, for example, four substrate units formed with electrical continuity with the substrate surface.

  FIG. 7 is a view showing a vertical section of the substrate units 16 to 19 constituting the multilayer board. As shown in FIG. 7, a predetermined wiring pattern is formed in each of these substrate units 15 to 19, and each wiring pattern is electrically connected in the thickness direction of the multilayer board by a conductor bump. It is like that. These substrate units 15 to 19 are stacked in a state where their positional relationships are arranged at appropriate positions as shown in FIG. 7 (STEP 8).

  In this state, the substrate units 15 to 19 are pressed in the thickness direction of the substrate (STEP 9) to form a multilayer structure, and the insulating material substrates of the substrate units 16 to 19 are cured by heating or the like (FIG. 8 / STEP 10).

  Next, each of the uppermost conductor plate 17a and the lowermost conductor plate 19a is subjected to etching or the like to form a pattern (STEP 11), thereby obtaining a final multilayer board. In the printed wiring board manufacturing method according to the present embodiment, only the core material 15 disposed in the center of the multilayer board is used as a cured substrate unit, and the uncured substrate units 16 to 19 are stacked on both sides of the substrate unit. Since the prepregs of the units 16 to 19 are cured, as shown in FIG. 8, all the conductor bumps stacked on both surfaces of the core material 15 are directed in the direction of the core material 15 (the center direction of the substrate). Therefore, since the bump shape inside the multilayer substrate is symmetric with respect to the center, a specific effect is obtained that the substrate is not easily warped or twisted after the heat treatment.

  In the printed wiring board manufacturing method according to the present embodiment, the insulating material used for the core material is lower in curability than the prepreg disposed on both sides of the core material, and is completely cured by heating twice. It is preferable to use an insulating material having a composition. By forming a core material using an insulating material having such a composition, a plurality of substrate units using an uncured insulating material are laminated on both sides of the core material, and then heated to obtain a core material. Since the degree of cure of the insulating material of the uncured substrate unit disposed on both sides of the core material is cured to the same level, the insulating material of the core material is not deteriorated by heating twice, and cracks caused by this deterioration And a special effect that migration can be prevented.

  (Third Embodiment) In this embodiment, a prepreg using a high glass transition type insulating material, for example, a bismaleide triazine resin, is used for only the three layers on the center side among the five-layer substrate units to be laminated. For the two outermost layers on the uppermost side and the lowermost side, a multilayer board was formed by the same method as in the first embodiment except that a prepreg using a high peel strength resin was used.

  In the printed wiring board manufacturing method according to the present embodiment, since the board unit using two different prepregs is heated and cured after lamination, the mechanical strength, heat resistance, and peel strength with the wiring pattern are high. Both were able to obtain an excellent multilayer board.

  Here, as the high peel strength type insulating material substrate used for the outermost layer, one having a peel strength of 1.2 N / mm or more with respect to the wiring pattern is preferable, and examples thereof include a glass fiber reinforced epoxy resin substrate prepreg.

  The reason why the peel strength with respect to the wiring pattern of the insulating material substrate used for the outer layer is limited to 1.2 N / mm or more is that when the peel strength with respect to the wiring pattern is less than 1.2 N / mm, the printed wiring board has an electronic component. This is because, when a drop test is performed after mounting, the parts are peeled off. This occurs because the adhesion strength between the insulating layer and the wiring pattern is small.

FIG. 3 is a vertical sectional view showing the procedure of the printed wiring board manufacturing method according to the first embodiment of the present invention. FIG. 3 is a vertical sectional view showing the procedure of the printed wiring board manufacturing method according to the first embodiment of the present invention. FIG. 3 is a vertical sectional view showing the procedure of the printed wiring board manufacturing method according to the first embodiment of the present invention. FIG. 3 is a vertical sectional view showing the procedure of the printed wiring board manufacturing method according to the first embodiment of the present invention. The flowchart of the printed wiring board manufacturing method which concerns on the 1st Embodiment of this invention. The vertical sectional view showing the procedure of the printed wiring board manufacturing method concerning a 2nd embodiment of the present invention. The vertical sectional view showing the procedure of the printed wiring board manufacturing method concerning a 2nd embodiment of the present invention. The vertical sectional view showing the procedure of the printed wiring board manufacturing method concerning a 2nd embodiment of the present invention. The flowchart of the printed wiring board manufacturing method which concerns on the 2nd Embodiment of this invention. The vertical sectional view which illustrated the manufacture procedure of the conventional multilayer board.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Conductor board, 2 ... Conductor bump, 3 ... Insulation material board | substrate, 1a ... Wiring pattern, 4 ... Film, 5 ... Core material.

Claims (2)

Forming a plurality of substantially conical conductor bumps on the conductor plate;
Disposing an uncured insulating material substrate on the conductor bump;
Pressurizing the conductive plate and the insulating material substrate at a temperature at which the insulating material substrate is not cured, and penetrating the conductive bumps; and
Patterning the conductor plate to provide a predetermined wiring pattern, and forming a substrate unit in which the conductor bumps penetrate the insulating substrate;
A step of forming a multilayer plate precursor by laminating a plurality of substrate units having the uncured insulating material substrate; and
Heating the multilayer board precursor under pressure to cure the multilayer precursor. A method for producing a printed wiring board, comprising: Conductive bumps are provided on the first surface and the second surface of the cured insulating material substrate, each having a wiring pattern, and electrically connecting the wiring patterns formed on the first surface and the second surface. Forming a core material to be embedded;
Forming a plurality of substantially conical conductor bumps on the conductor plate;
Disposing an uncured insulating material substrate on the conductor bump;
Pressurizing the conductive plate and the insulating material substrate at a temperature at which the insulating material substrate is not cured, and penetrating the conductive bumps; and
Patterning the conductor plate to provide a predetermined wiring pattern, and forming a substrate unit in which the conductor bumps penetrate the insulating substrate;
Forming a multilayer plate precursor by laminating and arranging at least one substrate unit having the uncured insulating material substrate on both surfaces of the core material;
Heating the multilayer board precursor under pressure to cure the multilayer board precursor.

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