JP2006059863A - Package substrate and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a package substrate wherein a part mounting pad is made smaller in diameter and the joint strength of the pad is improved. <P>SOLUTION: The package substrate has no land on the surface layer of a part mounting pad, and a circuit surface and an interlayer connection via surface are formed on the same plane as an insulating layer surface in the part mounting pad. Its manufacturing method includes a step where a nickel plating is used as a supporting body and an insulating layer and an interlayer connection via are formed thereon, and a step where the nickel supporting body is peeled off to form the part mounting pad having the interlayer connection via as the surface layer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a package substrate having a component mounting pad portion having a small diameter and high pad connection strength, and a method for manufacturing the same.

  2. Description of the Related Art In recent years, as represented by flip chip mounting, a technique for reducing the diameter of a component mounting pad on a package substrate on a component receiving side and reducing the pitch corresponding thereto is important. Here, a background art in a component mounting package substrate, particularly a component mounting pad portion, in the conventional technique will be described.

  As a conventional package substrate for component mounting, for example, a substrate having a structure shown in FIG. 5 has already been reported (see Patent Document 1). That is, first, the circuit portion 4a is formed on the core material portion 13 corresponding to the inner layer portion of the substrate as shown in FIG. 5 (a), and then a build-up structure is formed as shown in FIG. 5 (b) if necessary. Then, after the circuit is formed, the solder paste 14 is applied to the component mounting pad portions 19a and 19b, and the target component 15 is mounted, so that the substrate having the structure shown in FIG. Get. Incidentally, as the component mounting pad portion, in response to the background of the reduction of the component mounting area, a component using an interlayer connection via in addition to the component mounting pad portion (flat pad structure) 19a formed by circuit formation. Increasingly, a mounting pad portion (BVH pad structure) 19b is formed to make a structure that can be electrically connected between layers.

  However, the component mounting pad portion 19b having the BVH pad structure described in the previous section has the following problems in forming the component mounting pad with a small diameter and a small mounting area. .

  The first point is a structural problem of the conventional BVH. This is because a conventional BVH drilling method is mainly performed by a laser, so that the opening of the surface layer is larger than the opening of the bottom. Although this vessel-shaped structure with a large opening has advantages in terms of easy cleaning by a desmear process at the bottom and the ease of entering the plating solution for BVH, the component mounting pad having the small-diameter interlayer connection via is provided. When considered, if the BVH structure is made smaller in diameter, the opening at the bottom of the BVH becomes smaller in diameter, causing difficulty in cleaning by the desmear process and difficulty in entering the plating solution for BVH. It is easy to produce a defect and causes a structural defect in the background of forming a small component mounting pad portion.

Secondly, when the diameter of the component mounting pad portion is reduced, the area of the joint between the mounting pad and the insulating layer is reduced, and pad peeling occurs when the component is mounted or when a physical impact is applied. is there.
Japanese Patent Laid-Open No. 2004-140412

  In view of the conventional problems as described above, it is an object of the present invention to provide a package substrate and a manufacturing method thereof in which the component mounting pad portion is reduced in diameter and the connection strength of the pad portion is improved.

  The inventor has conducted various studies in order to solve the above problems. As a result, if the structure in which the land portion is not provided in the component mounting pad portion, the diameter of the pad portion can be reduced, and the land portion protruding in a hook shape is provided in the inner layer portion of the interlayer connection via that becomes the component mounting pad portion. Then, the present inventors have found that the connection strength of the pad portion can be improved and completed the invention.

  That is, the present invention provides a package substrate in which no land portion exists in the surface layer portion of the component mounting pad portion, and the circuit surface and the interlayer connection via surface are formed on the same plane as the insulating layer surface in the component mounting pad portion. It solves the above problems.

  In addition, the package substrate of the present invention is characterized in that the interlayer connection via has a land portion protruding in a hook shape on the inner layer portion.

  The package substrate of the present invention is characterized in that the component mounting pad portion is a cavity structure that accommodates components.

  The package substrate of the present invention is characterized in that a component is mounted on the component mounting pad portion.

  The present invention also includes a step of attaching nickel plating to one side of the conductor foil, a step of attaching copper plating on the nickel plating, a step of forming a circuit only for the copper plating portion, and the copper plating. After alternately laminating insulating layers and conductor layers, a step of forming an interlayer connection via directly on the nickel plating, and a step of forming a component mounting pad portion using the interlayer connection via as a surface layer portion by peeling off the nickel plating The above-described problems are solved by a method for manufacturing a package substrate including:

  The method for manufacturing a package substrate of the present invention is characterized in that, in the step of forming the interlayer connection via, a land portion protruding in a hook shape is formed on the inner layer portion.

  The method for manufacturing a package substrate of the present invention is characterized in that, in the step of forming the component mounting pad portion, the component mounting pad portion is a cavity structure that accommodates the component.

  Moreover, the manufacturing method of the package substrate of the present invention is characterized by further comprising a step of mounting a component after the formation of the component mounting pad portion.

  Since the package substrate of the present invention has a structure that does not have a land portion on the surface layer portion of the component mounting pad portion, the pad portion can be reduced in diameter, and the interlayer connection via serving as the component mounting pad portion can be realized. Since the land portion projecting in a hook shape is provided on the inner layer portion, the connection strength between the pad portion and the insulating layer can be improved. In addition, when components are actually mounted, the component mounting pad portion has a flat surface and a cavity structure, so that the yield and reliability of component mounting can be further improved.

Embodiments of the present invention will be described below with reference to the drawings.
In addition, particularly important points in the present invention are shown below, and their advantages are described in order.
Point 1): Structure suitable for reducing the diameter of the component mounting pad part Point 2): Structure suitable for increasing the connection strength of the component mounting pad part Point 3): Flattening structure of the component mounting pad part Point 4): Component mounting Cavity structure of pad part

  A method for manufacturing a package substrate according to the present invention will be described with reference to FIGS.

  First, as shown in FIG. 2 (a), for example, a base copper foil is prepared as the conductor foil 1, and electrolytic nickel plating 2 is attached to one surface thereof to obtain the structure shown in FIG. 2 (b). Next, electrolytic copper plating 3 is adhered to both surfaces of the obtained structure to obtain the structure shown in FIG. Next, as shown in FIG. 2D, the target circuit portion 4a is formed, and then the build-up portion is laminated to obtain the multilayer substrate shown in FIG.

  Next, as shown in FIGS. 3A to 3D, after the non-through hole 7 is formed with a laser and filled via plating 8 is processed, the interlayer connection vias 9 (no bottom land) and 10 (bottom part) are formed along with circuit formation. And a plurality of times of lamination as necessary, and interlayer connection vias 9 and 10 are formed to obtain a multilayer package substrate. The non-through hole 7 is formed by laser by controlling the laser conditions so that the bottom of the non-through hole 7 is directly above the nickel plating 2 or the circuit part (BVH receiving land) 4b.

  Next, as shown in FIGS. 4A and 4B, the circuit portion 4a is formed on the conductor layer 6 on the surface of the structure shown in FIG. Apply. Next, a circuit portion is formed on the copper plating 3 on the back surface of the structure shown in FIG. Incidentally, the circuit formation here is performed for each side because the structure shown in FIG. 3D is front and back and the conductor thickness is different. Further, at the time of circuit formation on the back surface, as shown in FIG. 4B, the copper plating 3 in the portion where the component mounting pad portion is formed is left.

  Next, resin or prepreg is applied or laminated to fill the vacant space on the side of the remaining copper plating 3 shown in FIG. 4B to form the cavity forming portion 11 shown in FIG. Thereafter, the remaining copper plating 3 is removed by etching to obtain the structure shown in FIG.

  Next, the nickel plating 2 shown in FIG. 4C is peeled off, and, as shown in FIG. Get the substrate. The component mounting on the package substrate of the present invention thus obtained is performed as shown in FIGS. 1 (a) and 1 (b). Thus, in the package substrate of the present invention, as shown in FIG. 1A, in the component mounting pad portion 12, the surface of the circuit portion 4a and the surface of the interlayer connection via 9 are formed on the same plane as the surface of the insulating layer 5. The component mounting pad portion 12 has a cavity structure due to the presence of the cavity forming portion 11.

  Point 1): Structure suitable for reducing the diameter of the component mounting pad

  In recent years, against the background of high-density boards, the present invention provides a structure capable of reducing the diameter of the component mounting pad portion. Conventionally, the component mounting pad portion has been mainly reduced in diameter by simply reducing the diameter of the pad portion by circuit formation. However, when the conventional method is used, as shown in FIG. 6, the component mounting pad portions 19 a and 19 b are peeled off from the insulating layer 5 at the bonding portion 17 corresponding to the interface, and a peeling portion 18 is formed. Quality will be impaired. In view of such a background, the present invention focused on two points: the bottom of the BVH structure is smaller in diameter than the surface layer opening, and the landless structure in which no land portion exists in the surface layer of the component mounting pad.

  When the present inventor considers the above two points, the conventional BVH structure is formed on the support medium. In addition, the necessary multilayer structure is stacked in the upward direction of the BVH structure. We thought it important to remove the support medium. At that time, in order to form the second landless structure, it was considered preferable that nothing is structurally present at the interface between the support medium and the BVH structure.

  Therefore, in the present invention, as described above, the support medium is the nickel plating 2 (FIG. 2B), the insulating layer 5 (FIG. 2E) is laminated above the nickel, and then the interlayer connection vias 9, 10 (FIG. 3C) is provided. Further, in order to reduce the diameter of the target component mounting pad portion, the nickel plating 2 is peeled off later (FIG. 4D), the bottom side of the interlayer connection via 9 is used as the surface layer portion, and the bottom portion of the interlayer connection via 9 is formed. Was used as the component mounting pad portion 12.

  The component mounting pad portion of the present invention thus obtained is a structure that satisfies the two small diameters and the landless structure.

  Point 2): Structure suitable for increasing the strength of the component mounting pad

  FIG. 6 schematically shows a state in which components are mounted on the component mounting pad portions 19a and 19b. For example, FIG. 6A shows a case where the component 15 is mounted on the component mounting pad portion (flat pad structure) 19a via the solder paste 14, and the interface between the component mounting pad portion 19a and the insulating layer 5 is shown. By reducing the diameter of the joint portion 17 corresponding to the contact portion, the joint area is reduced, and the contact portion between the component mounting pad portion 19a and the insulating layer 5, that is, the joint portion 17 is weakened. As a result, as shown in FIG. As described above, the peeled portion 18 may be generated when the component is mounted or when a physical impact is applied. The same applies to the component mounting pad portion (BVH structure) 19b shown in FIGS. 6D to 6F, and the peeled portion 18 may be generated as shown in FIG. 6F. is there. That is, when the component mounting pad portion is reduced in diameter, there is a problem of causing a problem of pad peeling.

  As in the case of the pad peeling problem as shown in FIG. 6, by making the component mounting pad portion small in diameter, the contact area of the pad portion becomes small, so that the pad is easily peeled off. Therefore, in the present invention, a structure having high strength, which is difficult to peel off even with a small-diameter pad, has been considered.

  In order to make the structure concrete, in the present invention, if a hook-like overhang structure having excellent locking properties is provided in the inner layer of the component mounting pad portion, the connection strength of the pad is improved. Thought. As shown in FIG. 1, the hook-shaped land portion 20 of the interlayer connection via 9 in FIG. 1A is effective. The hook-shaped land portion 20 is located at the bottom on the inner layer side of the component mounting pad portion, and has excellent locking properties with the insulating layer 5. With this structure, even a small-diameter pad is difficult to peel off and has high strength. The mounting pad portion can be held. Further, the durability of the structure according to the present invention is higher when it is pulled out in the vertical direction than the conventional component mounting pad portion.

  Point 3): Flattened structure of component mounting pad

  When specific component mounting is performed on the package substrate, it is preferable that the component mounting location is flat from the viewpoint of improving yield and reliability in mounting components. Therefore, in the present invention, as shown in FIG. 4 (c), the flat structure of the nickel plating 2 is used, and the flat portion is peeled off to remove the flat portion as shown in FIG. 4 (d). The surface of the interlayer connection via 9 was formed on the same surface as the surface of the insulating layer 5 to form the component mounting pad portion 12 having a flat structure.

  Point 4): Cavity structure near the component mounting pad

  Further, in the present invention, when a specific component is mounted on the package substrate, the advantage of preventing the occurrence of misalignment and the like is shown in FIG. The part 11 is provided, and the component mounting pad part 12 is a cavity structure. This cavity structure is advantageous because it can be created in FIGS. 4 (a) to 4 (c), that is, can be formed in the process of manufacturing the substrate.

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

  First, as shown in FIG. 2 (a), a base copper foil (thickness 250 μm) is prepared as the conductor foil 1, and a plating protective tape (or photosensitive dry film) is pasted on one side of the conductor copper foil 1, After the electrolytic nickel plating 2 (target thickness: 5 μm) was adhered, the plating protective tape was peeled off to obtain the structure shown in FIG. 2B having the nickel plating 2 on one side of the conductor foil 1.

  Next, as shown in FIG. 2 (c), the electrolytic copper plating 3 (target thickness: 20 μm) treatment is performed on both surfaces of the conductor foil 1 after the nickel plating 2 obtained in FIG. 2 (b). The structure shown in 2 (c) was obtained.

Next, as shown in FIG. 2 (d), an alkali etching resistant dry film resist is laminated on both sides of the structure obtained in FIG. 2 (c) by the circuit forming method in the subtractive construction method, Next, exposure (condition: 80 mj / cm ² ) and development (condition: 30 ° C.) are performed, then alkali etching (condition: 40 ° C.) of the circuit forming portion is performed, and the dry film resist is removed (condition: 2.5 vol. % Sodium hydroxide aqueous solution) to obtain the structure shown in FIG. 2D in which the desired circuit portion 4a was formed.

Next, the circuit part 4a of the structure shown in FIG. 2 (d) obtained above is subjected to CZ surface treatment made by MEC as a pre-lamination process, and the insulating layer 5 of the build-up part is made by Hitachi Chemical Co., Ltd. Using an insulating material (“prepreg MCL-E67” thickness 60 μm) and a standard copper foil material (thickness 12 μm) manufactured by Mitsui Kinzoku Co., Ltd. to be the conductor layer 6, laminating press (condition: temperature increase rate 3.4 ° C./min, The temperature was maintained at 185 ° C. for 68 minutes and the pressure was 35 kgf / cm ² ) to obtain the multilayer package substrate shown in FIG.

  Next, using the multilayer package substrate obtained in FIG. 2 (e), as shown in FIG. 3 (a) to FIG. . That is, the build-up part of the multilayer package substrate obtained in FIG. 2 (e) was irradiated with a laser to form non-through holes 7 (FIG. 3 (a)) and filled via plating 8 treatment (FIG. 3 (b)). Thereafter, a circuit was formed to form interlayer connection vias (without bottom lands) 9 and interlayer connection vias (with bottom lands) 10 (FIG. 3C). In forming the non-through hole 7 by laser, the laser conditions were controlled so that the bottom of the non-through hole 7 was directly above the nickel plating 2 or the circuit part (BVH receiving land) 4b.

  For this laser processing, “ML605GTX (oscillator: 5100U-S1)” manufactured by Mitsubishi Electric Corporation is used as a laser machine, and the insulating layer 5 is burned by using a mask for narrowing the laser beam. The laser energy was adjusted. As the laser irradiation conditions, a frequency of 100 Hz, a pulse width of 5 μm, a shot number of 5, a mask of 3.0 mm, an energy of 5.9 mj, a cycle pulse mode was used, and a target via diameter was set to 100 μm.

  The filled via plating 8 treatment includes chemical copper plating and electrolytic copper plating for via filling (target thickness: 20 μm) filled with copper plating as the filled via plating 8 after the non-through holes 7 are washed by a desmear process. Used to do.

  Further, the build-up portion after FIG. 3C was formed by sequentially laminating the insulating layer 5 and the conductor layer 6 in the same manner as described above.

  Next, circuit formation of the structure of FIG. 3D obtained as described above was performed as shown in FIGS. 4A and 4B. The circuit formation here was performed under different circuit formation conditions for each side, because the structure obtained in FIG. 3D had different conductor thicknesses on the front and back sides.

First, as shown in FIG. 4A, the circuit formation on the thin conductor layer 6 side was performed by the circuit formation method in the subtractive construction method. That is, a dry film resist is laminated on both surfaces of the structure shown in FIG. 4 (a), followed by exposure (condition: 80 mj / cm ² ) and development (condition: 30 ° C.). Etching was performed under conditions (40 ° C.) to form the target circuit portion 4a, and the structure shown in FIG. 4A was obtained. Next, as shown in FIG. 4B, a liquid photosensitive solder resist is applied to the surface on which the circuit portion 4a is formed in accordance with the structure of the target package substrate, and exposure (condition: 350 mj / cm ² ), development, and post cure (150 ° C., 1 h) were performed to form a solder resist 16.

Next, the circuit formation on the side of the thick copper plating 3 as the conductor layer was performed by the circuit formation method in the subtractive construction method. That is, an alkali etching resistant dry film resist is laminated on both surfaces of the structure shown in FIG. 4B, and then the copper plating 3 side is selectively exposed (condition: 70 mj / cm ² ) and developed ( The copper plating 3 was etched by leaving the portion of the copper plating 3 where the component mounting pad portion is to be formed with an alkaline etching solution (condition: 45 ° C.). Thereafter, the dry film resist was peeled off to obtain the structure shown in FIG.

  Next, in order to make the component mounting pad portion 12 into a cavity structure, the cavity forming portion 11 was formed in a space in which the circuit forming portion melted by the etching of the copper plating 3 was vacated. That is, the vacant space on the side of the remaining copper plating 3 in FIG. 4B was filled with the prepreg by the laminating method to form the cavity forming portion 11 shown in FIG. Thereafter, the remaining copper plating 3 was melted and removed under the above etching conditions to obtain a structure shown in FIG. 4C having a cavity structure on one side of the printed wiring board.

  Next, the nickel plating 2 exposed on the surface of the structure obtained in FIG. 4C is stripped with a nitric acid-based nickel plating stripper to obtain the package substrate of the present invention shown in FIG. It was.

  As shown in FIG. 1A, the package substrate of the present invention thus obtained is arranged with the component mounting pad portion 12 on the upper surface, and the component mounting pad portion 12 is connected to the component 15 via the solder paste 14. The package substrate of the present invention shown in FIG. 1B was obtained.

Test Example The pad portion for component mounting in the present invention can cope with a small-diameter structure, and in addition, has an effect that the connection strength value of the pad portion is high. Therefore, in order to specifically show that the effect of the package substrate of the present invention is superior to that of the conventional package substrate, the pad pull-out strength value is measured, and the comparison between the conventional package substrate and the package substrate of the present invention is performed. Was done.

  As a procedure for the pad pull-out strength value, a test substrate was first prepared. As the conventional package substrate, the substrate having the structure shown in FIG. 5C was used, and two types of flat pad structure (19a) and BVH structure pad (19b) were used for the component mounting pad portion. In addition, as the package substrate of the present invention, a substrate having the structure shown in FIG. 1A, that is, a substrate having the component mounting pad portion 12 of the cavity structure was used.

  In addition, with the intention of the small-diameter structure of the component mounting pad portion, three types of pads of φ100 μm, φ150 μm, and φ200 μm were used, and their strength values were compared.

  As a procedure leading to the measurement, a solder ball is mounted on the component mounting pad part for the previous test by reflow heating (heating peak: 240 ° C.), and an all-purpose pull tester (model: BT2400) manufactured by Arctech Co., Ltd. A measurement pin (model: BP-01-27L) manufactured by Arctec Co., Ltd. was embedded in the solder ball in a heated state, cooled to room temperature, and pulled strength value at a speed of 200 μm / second. Was measured. The results are shown in Tables 1 and 2.

  From the result of the above-mentioned pull-out measurement of the component mounting pad portion, it was confirmed that the strength value of the component mounting pad portion in the package substrate of the present invention is about three times stronger than the measurement value in the conventional package substrate.

  This test result is a result obtained from the structural characteristics of the component mounting pad portion 12 in the package substrate of the present invention. That is, this is because the hook-shaped land portion 20 of the interlayer connection via 9 in the component mounting pad portion 12 is firmly locked to the insulating layer 5 and, as a result, the pull-out strength value is improved.

  Therefore, it is clarified that this test result is advantageous in forming a reduced diameter of a pad portion for component mounting and a reduced mounting area as a package substrate required in the background art of the present invention. Yes.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. The schematic cross-sectional process explanatory drawing which shows the manufacture example of the package substrate of this invention. The schematic cross-sectional process explanatory drawing which shows the manufacture example of the package board | substrate of this invention following FIG. FIG. 4 is a schematic cross-sectional process explanatory diagram illustrating a manufacturing example of the package substrate of the present invention subsequent to FIG. 3. The schematic cross-sectional process explanatory drawing which shows the example of manufacture of the conventional package substrate. Schematic cross-sectional explanatory drawing which shows the malfunction at the time of mounting components on the conventional package substrate.

Explanation of symbols

1: Conductor foil 2: Nickel plating 3: Copper plating 4a: Circuit portion 4b: Circuit portion (BVH receiving land)
5: Insulating layer 6: Conductor layer 7: Non-through hole 8: Filled via plating 9: Interlayer connection via (no bottom land)
10: Interlayer connection via (with bottom land)
11: Cavity forming part 12: Component mounting pad part 13: Core material part 14: Solder paste 15: Part 16: Solder resist 17: Joining part 18: Peeling part 19a: Component mounting pad part (flat pad structure)
19b: component mounting pad (BVH pad structure)
20: Sponge land

Claims (8)

  A package substrate, wherein a land portion is not present in a surface layer portion of a component mounting pad portion, and a circuit surface and an interlayer connection via surface are formed on the same plane as the insulating layer surface in the component mounting pad portion.   The package substrate according to claim 1, wherein the interlayer connection via has a land portion protruding in a hook shape on the inner layer portion.   The package substrate according to claim 1, wherein the component mounting pad portion is a cavity structure that accommodates a component.   The package substrate according to any one of claims 1 to 3, wherein a component is mounted on the component mounting pad portion.   A step of attaching nickel plating to one side of the conductor foil, a step of attaching copper plating on the nickel plating, a step of forming a circuit only on the copper plating portion, and an insulating layer and a conductor layer on the copper plating. After alternately laminating layers, a step of forming an interlayer connection via directly on the nickel plating and a step of forming a component mounting pad portion having the interlayer connection via as a surface layer by peeling of the nickel plating are included. A manufacturing method of a package substrate characterized by the above.   6. The method of manufacturing a package substrate according to claim 5, wherein, in the step of forming the interlayer connection via, a land portion protruding in a hook shape is formed on the inner layer portion.   7. The method of manufacturing a package substrate according to claim 5, wherein in the step of forming the component mounting pad portion, the component mounting pad portion is a cavity structure that accommodates the component.   8. The method of manufacturing a package substrate according to claim 5, further comprising a step of mounting a component after the component mounting pad portion is formed.

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