Wiring board

Abstract

To solve the problem that the removal of residue of flux between a lower surface of an electronic component and an upper surface of a solder resist layer is difficult, and the countermeasures for the difficulty is requested.SOLUTION: A wiring board 10 includes: an insulating layer 21; an electrically conductive layer 20 laminated on the insulating layer and including a plurality of pads; and a solder resist layer 11 laminated on the electrically conductive layer and having a plurality of connection openings for exposing the plurality of pads. The plurality of pads include a pair of component connection pads 14 to which a pair of electrodes 101 of an electronic component including a rectangular parallelepiped chip 100 are soldered. The wiring board includes a pair of insulating support bases 16 that abut on the pair of electrodes and support the entire electronic component in a state of being floated from an upper surface of the solder resist layer. The insulating support base has a two-layered structure of a first insulating support layer 16A and a second insulating support layer 16B.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a wiring substrate. [Background technology]

[0002] BACKGROUND ART Known conventional wiring boards have a pair of electrodes of an electronic component soldered thereto (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-147982 A (paragraphs

[0047] to

[0056] , Figure 1) Summary of the Invention [Problem to be solved by the invention]

[0004] However, the above-mentioned conventional wiring board has a problem in that it is difficult to remove the flux residue between the electronic component and the wiring board. [Means for solving the problem]

[0005] One aspect of the invention is a wiring board comprising an insulating layer, a conductive layer laminated on the insulating layer and including a plurality of pads, and a solder resist layer laminated on the conductive layer and having a plurality of connection openings exposing the plurality of pads, wherein the plurality of pads include a pair of component connection pads to which a pair of electrodes of an electronic component are soldered, and further comprising a pair of insulating supports that abut the pair of electrodes and support the entire electronic component in a state where it is floating above the upper surface of the solder resist layer. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a cross-sectional view of a wiring board and an electronic component according to the present disclosure. [Figure 2] FIG. 2 is a perspective view of a wiring board and an electronic component. [Figure 3] FIG. 3 is an explanatory diagram showing the process of forming an insulating support base. [Figure 4] FIG. 4 is an explanatory diagram showing the mounting process of electronic components. [Figure 5] 5A is a cross-sectional view of a wiring board according to another embodiment, FIG. 5B is a cross-sectional view of a wiring board according to another embodiment, and FIG. 5C is a cross-sectional view of a wiring board according to another embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] [First embodiment] A wiring board 10 according to an embodiment of the present disclosure will be described below with reference to Fig. 1 to Fig. 4. The wiring board 10 is a multilayer wiring board in which a plurality of conductive layers 20 and insulating layers 21 are stacked, for example, as shown in Fig. 1, and a solder resist layer 11 is stacked as the outermost layer. Of the plurality of conductive layers 20 and insulating layers 21, only the outermost conductive layer 20 and insulating layer 21 are shown in Fig. 1. In the following description, the upper side in Fig. 1 will simply be referred to as the upper side.

[0008] A plurality of electronic components including a rectangular parallelepiped chip 100 are mounted on the upper surface of the solder resist layer 11. The rectangular parallelepiped chip 100 shown in FIG. 1 is, for example, a ceramic capacitor having a rectangular parallelepiped shape extending parallel to the upper surface of the wiring substrate 10, and both ends of the chip having a pair of electrodes 101 covered with metal. Note that the rectangular parallelepiped chip 100 is not limited to a ceramic capacitor, and may also be a chip resistor, a chip coil, a chip diode, a chip LED, or the like. Hereinafter, the rectangular parallelepiped chip 100 will be simply referred to as the "chip 100."

[0009] Conductive layer 20 is provided with a plurality of pads to which a plurality of electronic components are connected, and solder resist layer 11 is formed with a plurality of openings corresponding to the plurality of pads formed on conductive layer 20. Fig. 1 shows a pair of component connection pads 14 among the plurality of pads, which correspond to a pair of electrodes 101 of chip 100, and a pair of connection openings 13 corresponding thereto.

[0010] 2, a pair of component connection pads 14 is, for example, quadrilateral in plan view, and the quadrilateral has a rectangular shape with the long side being the side where the pair of component connection pads 14 are adjacent to each other. The outer edge of each component connection pad 14 is covered by the edge of the connection opening 13 in the solder resist layer 11.

[0011] An insulating support base 16 is provided at approximately the center in the short direction of the component connection pad 14. The insulating support base 16 has, for example, a rectangular cross section and extends across the opposing short sides of the connection opening 13, as shown in FIG.

[0012] Specifically, the insulating support base 16 has a two-layer structure consisting of a first insulating support layer 16A and a second insulating support layer 16B. The first insulating support layer 16A is integrally formed with the solder resist layer 11, and its upper surface is flush with the upper surface of the solder resist layer 11. The second insulating support layer 16B is laminated on the upper surface of the first insulating support layer 16A over the entire length of the first insulating support layer 16A, and is narrower than the first insulating support layer 16A. The height of the second insulating support layer 16B is 3 μm to 15 μm. The second insulating support layer 16B positions the upper end of the insulating support base 16 above the upper surface of the solder resist layer 11.

[0013] In this embodiment, second insulating support layer 16B is narrower than first insulating support layer 16A, but is not limited to this and may have the same shape and size as first insulating support layer 16A. Also, second insulating support layer 16B may be wider, or a part of second insulating support layer 16B may protrude beyond first insulating support layer 16A.

[0014] A method for manufacturing the wiring board 10 of the present disclosure will be described below with reference to Fig. 3. Note that the steps up to the formation of the conductive layer 20 including the component connection pads 14 below the solder resist layer 11 are performed by a known method, and therefore a description up to that point will be omitted.

[0015] (1) A liquid solder resist that hardens when exposed to ultraviolet light is sprayed onto the conductive layer 20 using a roll coater or the like, forming a solder resist film 11A. After the solder resist film 11A has dried, an opening mask film 18A is placed on top of the solder resist film 11A and subjected to ultraviolet exposure processing (see FIG. 3A). This hardens only the required portions of the first insulating support film 16A. Note that in the opening mask film 18A shown in FIG. 3A, the white portions are translucent, and the black portions are opaque. The same is true for the support base mask film 18B, which will be described later.

[0016] (2) Unnecessary portions of the solder resist film 11A are removed, thereby forming the solder resist layer 11 and the first insulating support layer 16A (see FIG. 3B).

[0017] (3) Next, liquid solder resist is sprayed onto the solder resist layer 11 to form a support base solder resist film 11B. After the support base solder resist film 11B is dried, a support base mask film 18B is placed on top of the support base solder resist film 11B, and an ultraviolet exposure process is performed (see FIG. 3C).

[0018] (4) The portions of the support base solder resist film 11B that have been irradiated with ultraviolet light are cured. Next, unnecessary portions of the support base solder resist 11B are removed. This forms a second insulating support layer 16B, and the insulating support base 16 has a two-layer structure.

[0019] Although a liquid solder resist is used in this embodiment, a film solder resist may also be used. In this case, the insulating support base 16 is formed by laminating a dry film solder resist 11A and a support base dry film solder resist 11B using a vacuum laminator.

[0020] The chip 100 is mounted on the wiring substrate 10 by, for example, the method shown in FIG.

[0021] (1) A metal mask 40 is placed on the upper surface of the wiring board 10. The metal mask 40 is provided with a plurality of openings 13A including openings corresponding to the connection openings 13 (see FIG. 4A).

[0022] (2) The wiring board 10 is set in a solder printing machine, and cream solder 41A is placed on the metal mask 40. When the squeegee 42 is moved from one end to the other while in contact with the upper surface of the metal mask 40, the cream solder 41A is filled through the multiple openings 13A (see FIG. 4B).

[0023] (3) After the metal mask 40 is removed from the wiring board 10, the wiring board 10 is moved into a chip mounter, and the chip 100 is placed on the location where the cream solder 41A has been printed (see FIG. 4C).

[0024] (4) When wiring board 10 is transferred to a reflow furnace and cream solder 41A is heated, the granular solder melts, the flux vaporizes, and chip 100 sinks in. At this time, even if chip 100 sinks to the maximum extent, gap D is maintained between the bottom surface of chip 100 and the top surface of solder resist 11 by abutting on insulating support base 16 (see FIG. 4D).

[0025] In this way, the insulating support 16 ensures a gap D between the underside of the chip 100 and the upper surface of the solder resist layer 11, which makes it easier to remove flux residue between them in the subsequent cleaning process. Furthermore, not only the cleaning liquid but also air can easily pass through the gap, which shortens the time required for the drying process.

[0026] Furthermore, the first insulating support layer 16A of the insulating support base 16 is molded integrally with the solder resist layer 11, and both ends thereof are connected to the opening edge portions of the connection openings 13. This prevents peeling of the insulating support base 16. In addition, the insulating support base 16 can be formed simply by stacking the second insulating support layer 16B on the first insulating support layer 16A, which can be formed simultaneously with the formation of the solder resist layer 11.

[0027] Furthermore, insulating support base 16 extends in a direction perpendicular to the arrangement direction of component connection pads 14, in other words, along the long sides of chip 100. In this case, chip 100 is less likely to slip off insulating support base 16 than in the case where insulating support base 16 extends along the arrangement direction of component connection pads 14, and therefore chip 100 is more stably loaded.

[0028] Furthermore, since the chip 100 is supported by the insulating support base 16 at a position away from the component connection pad 14, the chip 100 is prevented from sinking too far into the cream solder 41A, thereby preventing the cream solder 41A pressed by the chip 100 from spreading outside the component connection pad 14.

[0029] [Other embodiments] (1) In this embodiment, the insulating support base 16 is formed on the upper surface of the component connection pad 14. However, it may be configured to penetrate the component connection pad and be connected to the insulating layer, as in the case of the insulating support base 17 shown in FIG. 5A.

[0030] (2) As shown in Fig. 5B, second insulating support layers 17B may be disposed inside the opening edges of adjacent connection openings 13 to form insulating support bases 17, or as in this embodiment, insulating support bases 16 may be disposed in the centers of component connection pads 14. In this case, the spacing between insulating support bases 16 can be made wider than in the case of Fig. 5B, and chips 100 can be supported at positions closer to the centers of electrodes 101, allowing chips 100 to be stably loaded.

[0031] (3) Also, as shown in Fig. 5C, a second insulating support layer 17B may be disposed on the outer side of the opening edges of adjacent connection openings 13 to serve as an insulating support base 17. This can prevent the cream solder 41A from spreading to unintended areas.

[0032] (4) In this embodiment, the insulating support base 16 is disposed between the opposing edges of the connection opening 13. However, it may be in the form of a cantilever extending from either edge of the opening. Also, it may not be connected to the solder resist layer 11, but may be disposed, for example, near the center of the component connection pad 14.

[0033] (5) Furthermore, the cross section of the insulating support base 16 does not have to be rectangular, and may be, for example, semicircular in cross section with chamfered corners, which can prevent the insulating support base 16 from getting caught on the corners and peeling off from the wiring substrate 10.

[0034] Although the present specification and drawings disclose specific examples of the technology included in the scope of the claims, the technology described in the claims is not limited to these specific examples, but also includes various modifications and variations of the specific examples, and also includes parts of the specific examples taken out alone. [Explanation of symbols]

[0035] 10. Wiring board 11 Solder resist layer 13 Connection opening 14 Component connection pads 16 Insulating support base 16A First insulating support layer 16B Second insulating support layer 20 Conductive layer 21 Insulating layer 100 chips 101 Electrode

Claims

1. an insulating layer; a conductive layer laminated on the insulating layer and including a plurality of pads; a solder resist layer laminated on the conductive layer and having a plurality of connection openings exposing the plurality of pads; In a wiring board, the plurality of pads include a pair of component connection pads to which a pair of electrodes of an electronic component are soldered, A pair of insulating support bases are provided in contact with the pair of electrodes to support the entire electronic component in a state where it is floating above the upper surface of the solder resist layer.

2. 2. The wiring board according to claim 1, wherein each of the insulating support bases is superimposed on the component connection pad and protrudes to a position above the solder resist layer.

3. The wiring board according to claim 2 , wherein each of the insulating support bases is connected to the solder resist layer.

4. 4. The wiring board according to claim 3, wherein both ends of each of the insulating supports are connected to the solder resist layer.

5. 2. The wiring board according to claim 1, wherein each of the insulating support bases extends in a direction perpendicular to the direction in which the pair of component connection pads are arranged.

6. 6. The wiring board according to claim 1, wherein the electronic component is a rectangular parallelepiped chip component.

7. the insulating support base has a two-layer structure including a first insulating support layer overlaid on the component connection pads and a second insulating support layer overlaid on the first insulating support layer, The wiring board according to claim 1 , wherein the first insulating support layer is larger than the second insulating support layer in a plan view.

8. The wiring board according to claim 7 , wherein the first insulating support layer is a part of the solder resist.

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