JP2013211386A - Led mounting substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED mounting substrate equipped with a solder resist which is capable of suppressing soaking of silver plating thereinto, capable of roll lamination and capable of obtaining adhesion to a reflection layer of silicon based resin while surely closing a through-hole for an end surface electrode formation.SOLUTION: An LED mounting substrate includes: a through-hole for an end surface electrode; a reflection resin layer which is filled into a gap of a surface layer circuit including a land of this through-hole; a liquid solder resist having a silver plating layer and a base plating formed in the surface layer circuit and the through-hole and formed in a boundary area between the reflection resin layer of the land end of the through-hole; and a film-like solder resist formed on this liquid solder resist.

Description

  The present invention relates to an LED mounting wiring board and a manufacturing method thereof, and more particularly to an LED mounting wiring board having end face electrode through holes tented with a film solder resist and a manufacturing method thereof.

  In recent years, with the widespread use of LEDs, many LED mounting wiring boards having end face electrode through holes tented with a film-like solder resist are produced.

  As a method of forming the through hole for the end face electrode tented with such a film-like solder resist, a method of patenting with only the film-like solder resist (Patent Document 1), or a liquid solder on the film-like solder resist A method of applying a resist (Patent Document 2, Patent Document 3) and the like are disclosed.

JP 11-351704 A Japanese Patent Laying-Open No. 2005-064087 JP 2008-166634 A

  However, film solder resists that tent through-holes for end-face electrodes are less resistant to precious metal plating than general liquid solder resists, and the interface between film solder resist and copper foil after precious metal plating As a result, it is difficult to ensure sufficient adhesion.

  In the method of Patent Document 1, the penetration of the noble metal plating solution occurs from both the interface between the film-like solder resist and the copper foil on the tented surface and the interface between the film-like solder resist and the copper foil inside the through hole. There is a problem that it is difficult to ensure sufficient adhesion between the film-like solder resist and copper.

  In the methods of Patent Document 2 and Patent Document 3, since the penetration of the noble metal plating solution occurs from the interface between the film-like solder resist and the copper foil inside the through hole, the adhesion between the film-like solder resist and the copper foil is increased. There is a problem that it is difficult to secure enough.

  The present invention has been made in view of the above-mentioned problems, and can reliably suppress penetration of silver plating, roll lamination while reliably closing the through hole for forming the end face electrode, and can also reflect the reflection of the silicone resin. It aims at providing the wiring board for LED mounting provided with the soldering resist from which adhesion | attachment with a layer is obtained.

The present invention is characterized by the following.
1. A through hole for an end face electrode, a reflective resin layer filled in a gap of a surface layer circuit including a land of the through hole, and a silver plating layer formed in the surface layer circuit, and a land end of the through hole A wiring board for mounting LED having a liquid solder resist formed on a boundary region with a reflective resin layer of a portion and a film solder resist formed on the liquid solder resist.
2. The wiring board for mounting an LED according to item 1, wherein an end portion of the film-like solder resist formed on the liquid solder resist is formed on the liquid solder resist.
3. The LED mounting wiring board according to Item 1 or 2, wherein the liquid solder resist formed on the boundary region with the reflective layer at the land end of the through hole is formed on the base plating surface of the silver plating layer.
4. The LED mounting wiring board according to any one of items 1 to 3, wherein the reflective resin layer filled in the gap of the surface layer circuit contains a silicone resin.

  According to the present invention, a solder resist capable of suppressing penetration of silver plating, capable of roll laminating while securely closing a through hole for forming an end face electrode, and having adhesion with a reflective layer of a silicone resin is provided. In addition, an LED mounting wiring board can be provided.

It is sectional drawing of the wiring board for LED mounting which concerns on Example 1 (1st Embodiment) of this invention. It is sectional drawing of the wiring board for LED mounting which concerns on Example 2 (2nd Embodiment) of this invention. It is sectional drawing of the conventional wiring board for LED mounting. It is sectional drawing showing the process of the wiring board for LED mounting which concerns on Example 1 (1st Embodiment) of this invention. It is sectional drawing showing the process of the wiring board for LED mounting which concerns on Example 2 (2nd Embodiment) of this invention.

  Examples of embodiments of the wiring board of the present invention are shown in FIGS. The first embodiment shown in FIG. 1 has an end face electrode through hole 4 and a reflective resin layer 3 filled in a gap of a surface layer circuit 10 including a land 11 of the through hole 4. Further, the surface layer circuit 10 formed of copper 5 (copper foil or copper plating) has a nickel plating 6, a gold plating layer 7, and a silver plating 8 plating which are base plating layers. Further, the through hole 4 has a nickel plating 6 and a gold plating layer 7 which are base plating layers. Further, the liquid solder resist 2 is formed on the boundary area between the end of the land 11 of the through hole 4 and the reflective resin layer 3, and the film solder resist 1 is formed on the liquid solder resist 2.

  Further, the second embodiment shown in FIG. 2 includes the end face electrode through hole 4 and the reflective resin layer 3 filled in the gap of the surface layer circuit 10 including the land 11 of the through hole 4. Moreover, the surface layer circuit 10 formed of copper 5 (copper foil or copper plating) has nickel plating 6 and silver plating 8 which are base plating layers. Similarly, the through hole 4 has a nickel plating 6 and a silver plating layer 8 which are base plating layers. Further, the liquid solder resist 2 is formed on the boundary area between the end of the land 11 of the through hole 4 and the reflective resin layer 3, and the film solder resist 1 is formed on the liquid solder resist 2.

  The end face electrode through hole 4 is mounted with an LED, molded with mold resin or the like, and then half cut by dicing or the like so that the end face electrode through hole 4 passes through the center of the end face electrode through hole 4. The exposed inner wall (end face) becomes an electrode for soldering.

  The reflective resin layer 3 reflects light emitted from the LED, and has a higher reflectance at a wavelength of 460 nm than a base material used for the LED mounting wiring board. Here, the LED refers to a light emitting element using a light emitting diode. Examples of the material used for the reflective resin layer include a silicone resin or an epoxy resin mixed with finely divided titanium oxide or the like. The reflective resin layer 3 is, for example, applied in an ink state so as to overlap the surface circuit 10 including the gap of the surface circuit 10 by printing or the like, and cured, and then the entire surface circuit 10 is formed. The gap of the surface circuit 10 can be filled by polishing the entire surface so as to be exposed. As described above, the reflective resin layer 3 filled in the gap between the surface circuits 10 allows the base material having a relatively low reflectance exposed in the gap between the surface circuits 10 to have a higher reflectance. Therefore, the reflectance as a whole can be improved. By using a silicone-based resin for the reflective resin layer 3, it is possible to reduce a decrease in luminance after LED mounting.

  It has a base plating layer and a gold plating layer or a base plating layer and a silver plating layer formed in the surface layer circuit 10 and the through hole 4. Thereby, the reflectance of the light from LED on the surface circuit 10 can be improved.

  It has a liquid solder resist 2 formed on a boundary region with the reflective resin layer 3 at the end of the land 11 of the through hole 4 and a film-like solder resist 1 formed on the liquid solder resist 2. The underlying liquid solder resist 2 has high adhesion and ensures adhesion even when exposed to a plating solution for forming an underlying plating layer such as the nickel plating layer 6, a gold plating layer 7, or a silver plating layer 8. Can do. In addition, a tent can be reliably formed on the through hole 4 by the film solder resist 1 formed on the liquid solder resist 2. That is, the interface between the copper 5 and the liquid resist 2 forming the surface circuit 10 and the interface between the liquid resist 2 and the film resist 1 are not easily affected by the nickel plating solution, the gold plating solution, and the silver plating solution. There is no penetration of the plating solution after plating, and sufficient adhesion between the liquid resist 2 and the film-like resist 1 can be ensured. In order to improve the adhesion between the liquid resist 2 and the copper 5, it is desirable to roughen the surface of the copper 5.

  Examples of the method for manufacturing an LED mounting wiring board of the present invention include a step of forming a silicone-based reflective resin layer 3 as shown in FIGS. 4 (A) to (F) and FIGS. 5 (A) to (E). A step of forming a liquid resist 2 and a step of forming a film-like solder resist 1 on the liquid resist 2;

  As shown in FIG. 4, before forming the film-like solder resist 1, nickel plating 6 and gold plating 7 are performed, and then the silver mounting 8 is performed only on the LED mounting surface, thereby achieving a high aspect ratio (aspect ratio 1). There is also no problem with plating deposition in the through hole. Here, the aspect ratio refers to the ratio of plate thickness: through-hole hole diameter.

  When the aspect ratio is 1 or less, the plating depositability in the through hole is improved. Therefore, a method of performing nickel plating 6 and silver plating 8 after forming the film-like solder resist 1 as shown in FIG. 5 is also used. Can do.

  Examples of the present invention will be described below, but the present invention is not limited to the examples.

Example 1
After drilling with a drill with a diameter of 0.4 mm for the end face electrode through hole 4 in CCL-HL820 (trade name, manufactured by Mitsubishi Gas Chemical Co., Ltd.) having a plate thickness of 0.4 mm and a copper foil thickness of 18 μm, Through-hole plating was applied to a thickness of 20 μm to prepare a substrate on which the surface circuit 10 was formed (FIG. 4A). Since this substrate has a drill diameter of 0.4 mm and a through-hole plating thickness of 20 μm, the hole diameter after through-hole plating is 0.36 mm. Further, since the plate thickness is 0.4, the copper foil thickness is 18 μm, and the through-hole plating is 20 μm, the depth of the through-hole 4 is 0.476 mm. For this reason, this substrate has an aspect ratio exceeding 1.

  A silicone-based reflective resin RG-12-6-2 (trade name, manufactured by Ein Co., Ltd.) is screen-printed as the reflective resin layer 3 on the substrate on which the surface circuit 10 is formed. Filled with reflective resin. At this time, printing was performed so as to overlap about 0.2 mm on the surface circuit 10 including the gap of the surface circuit 10, and after temporary drying at 80 ° C. for 30 minutes, the substrate surface was buffed. Thereby, the gap of the surface circuit 10 could be filled with the silicone-based reflective resin without any gap (FIG. 4B). After buffing, the film was fully cured at 150 ° C. for 1 hour.

  Next, the surface of the surface circuit 10 formed of copper 5 is subjected to a roughening treatment CZ8100 (trade name, manufactured by MEC Co., Ltd.), and then the reflective resin layer 3 at the end of the land 11 of the through hole 4 On the boundary region, PSR4000 G30 (trade name, manufactured by Taiyo Ink Manufacturing Co., Ltd.), which is a liquid solder resist 2, was formed (FIG. 4C).

  Next, electroless nickel plating (thickness 5 μm) as an undercoat and electroless gold plating (thickness 0.05 μm) thereon were performed (FIG. 4D).

  Next, DM155 (manufactured by Nichigo Morton Co., Ltd.) was formed as a film solder resist 1 on PSR4000 G30 (manufactured by Taiyo Ink Manufacturing Co., Ltd.), which is a liquid solder resist 2 (FIG. 4E).

  Next, electrolytic silver plating (thickness: 1 μm) was performed only on the same surface on which the film-like solder resist 1 was formed. At this time, the surface where the film-like solder resist 1 was not formed was completely masked with a masking tape N380 (trade name, manufactured by Nitto Denko Corporation). After the silver plating treatment, the masking tape was peeled off (FIG. 4 (F)).

  In the substrate produced by the construction method of Example 1 (FIGS. 4A to 4F), no penetration of the plating solution around the film solder resist 1 was confirmed. There was no tear of the film-like solder resist 1 in the finished product, and no occurrence of peeling of the film-like solder resist 1 in the tape peel test was confirmed. In the tape peel test, the new adhesive surface of the tape (transparent adhesive tape with a width of 12 mm specified in JISZ1522) is pressure-bonded so that no bubbles remain. After about 10 seconds, the tape is quickly applied in a direction perpendicular to the substrate surface. It was done by the method of peeling. Hereinafter, the method and conditions of the tape peel test are the same.

  The plating coverage in the end face electrode through hole 4 was good, and the end face electrode through hole 1 in which the nickel plating layer 6 and the gold plating layer 7 were not deposited was not confirmed.

(Example 2)
After drilling with a 0.4 mm diameter drill for the end face electrode through hole 4 in CCL-HL820 (trade name, manufactured by Mitsubishi Gas Chemical Co., Ltd.) having a plate thickness of 0.2 mm and a copper foil thickness of 18 μm, Through-hole plating was applied to a thickness of 20 μm to prepare a substrate on which the surface circuit 10 was formed (FIG. 5A). Since this substrate has a drill diameter of 0.4 mm and a through-hole plating thickness of 20 μm, the hole diameter after through-hole plating is 0.36 mm. Further, since the plate thickness is 0.2, the copper foil thickness is 18 μm, and the through hole plating is 20 μm, the depth of the through hole 4 is 0.276 mm. For this reason, this substrate has an aspect ratio of less than 1.

  Thereafter, formation of a silicone-based reflective resin RG-12-6-2 (trade name, manufactured by Ein Co., Ltd.), which is the reflective resin layer 3, and PSR4000 G30 (trade name, manufactured by Taiyo Ink Manufacturing Co., Ltd.), which is the liquid solder resist 2 ) Was formed in the same manner as in Example 1 (FIGS. 5B and 5C).

  Next, DM155 (trade name, manufactured by Nichigo Morton Co., Ltd.), which is a film-like solder resist 1, was formed on PSR4000 G30 (trade name, manufactured by Taiyo Ink Manufacturing Co., Ltd.), which is a liquid solder resist 2 (FIG. 5). (D)).

  Next, plating treatment of electrolytic nickel plating (thickness 5 μm) as an underlying plating and electrolytic silver plating (thickness 1 μm) thereon was performed (FIG. 5E).

  In the substrate produced by the construction method of Example 2 (FIGS. 5A to 5E), no penetration of the plating solution around the film solder resist 1 was confirmed. There was no tear of the film-like solder resist 1 in the finished product, and no occurrence of peeling of the film-like solder resist 1 in the tape peel test was confirmed. The tape peel test was conducted in the same manner as in Example 1.

  The plating coverage in the end face electrode through hole 4 was good, and the end face electrode through hole 1 in which the nickel plating layer 6 and the silver plating layer 8 were not deposited was not confirmed.

(Comparative example)
After drilling with a drill with a diameter of 0.4 mm for the end face electrode through hole 4 in CCL-HL820 (trade name, manufactured by Mitsubishi Gas Chemical Co., Ltd.) having a plate thickness of 0.4 mm and a copper foil thickness of 18 μm, FIG. 4A shows a substrate on which through-hole plating is applied to a thickness of 20 μm and a surface circuit 10 is formed. This substrate has an aspect ratio exceeding 1 as in the first embodiment.

  Next, DM155 (trade name, manufactured by Nichigo Morton Co., Ltd.), which is a film-like solder resist 1, was formed on the through hole 4 for the end face electrode (FIG. 3).

  Next, electroless nickel plating (thickness 5 μm) as an undercoat and electroless gold plating (thickness 0.05 μm) thereon were performed.

  Next, electrolytic silver plating (thickness: 1 μm) was performed on the same surface on which the film-like solder resist 1 was formed. At this time, the surface where the film-like solder resist 1 was not formed was completely masked with a masking tape N380 (trade name, manufactured by Nitto Denko Corporation). After the silver plating treatment, the masking tape was peeled off.

  In the substrate prepared by the method of the comparative example, the penetration of the plating solution around the film solder resist 1 was clearly confirmed. The film-like solder resist 1 in the finished product was broken and peeled off, and almost all the film-like solder resists were peeled off in the tape peel test. The tape peel test was conducted in the same manner as in Example 1.

  The plating around the end face electrode through hole 4 was poor, and the end face electrode through hole 1 without the nickel plating layer 6 and the gold plating layer 7 was confirmed with high probability.

1. 1. Film-like solder resist 2. Liquid solder resist Reflective resin layer4. 4. Through hole for end face electrode Copper 6. 6. Nickel plating layer Gold plating layer8. 8. Silver plating layer Base material 10. Surface circuit 11. land

Claims (4)

  A through hole for an end face electrode; a reflective resin layer filled in a gap of a surface layer circuit including a land of the through hole; and a silver plating layer formed in the surface layer circuit; An LED-mounting wiring board having a liquid solder resist formed on a boundary region with a reflective resin layer and a film-like solder resist formed on the liquid solder resist.   2. The LED mounting wiring board according to claim 1, wherein an end portion of the film-like solder resist formed on the liquid solder resist is formed on the liquid solder resist.   3. The LED mounting wiring board according to claim 1, wherein the liquid solder resist formed on the boundary region between the land end portion of the through hole and the reflective resin layer is formed on the base plating surface of the silver plating layer.   4. The LED mounting wiring board according to claim 1, wherein the reflective resin layer filled in the gap of the surface layer circuit contains a silicone resin.

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