JP3675358B2 - Display body and method of manufacturing printed wiring board used therefor - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention provides a display body provided with a non-through hole that accommodates a light emitting element such as an LED, and a noble metal plating film that reflects light on the inner wall surface of the non-through hole, and a method of manufacturing a printed wiring board used therefor About.
[0002]
[Prior art]
A gold plating film for reflecting the light emitted from the LED is formed on the inner wall of the non-through hole of this type of printed wiring board, and the printed wiring board is superimposed on the second printed wiring board on which the LED is mounted. It is fixed like this. The second printed wiring board is formed with an anode terminal portion and a cathode terminal portion corresponding to the non-through holes of the first printed wiring board, and the LED is electrically connected to the anode terminal portion and the cathode terminal portion by wire bonding or the like. So as to be connected to each other and accommodated in the non-through hole. In this case, when the gold plating film formed in the non-through hole of the first printed wiring board is formed up to the lower end of the non-through hole, the gold terminal film is formed on the second printed wiring board. There is a risk of electrical short-circuit by contact with the cathode terminal and the wiring conductor. In order to prevent this, the gold plating film formed at the lower end portion of the non-through hole is partially removed.
[0003]
FIG. 7 is a cross-sectional view for explaining a conventional method of manufacturing a reflector.
In FIG. 1A, reference numeral 60 denotes a reflector made of plastic, and is provided with a through hole 61 in which an LED is accommodated. The through hole 61 is provided on the lower side with a small diameter portion 62 having a diameter of D1 and an upper side of the small diameter portion 62, and the upper end diameter D2 is larger than the diameter D1 of the small diameter portion 62. It is formed by a large mortar-shaped large-diameter portion 63 formed large.
[0004]
As shown in FIG. 2B, after forming the gold plating film 64 on the inner wall surface of the small diameter portion 62 and the large diameter portion 63 of the through hole 61, the diameter D3 is slightly larger than the diameter D1 of the small diameter portion 62. With the drill 65, the gold plating film 64 formed on the inner wall surface of the small diameter portion 62 is removed as shown in FIG. In FIG. 4D, reference numeral 70 denotes a printed wiring board on which an anode terminal portion 71 and a cathode terminal portion 72 are formed. The anode terminal portion 71 and the cathode terminal portion 72 are made to correspond to the through holes 61, and The reflector 60 is overlaid on the printed wiring board 70. The LED 75 is electrically connected to the anode terminal portion 71 and the cathode terminal portion 72 by wire bonding or direct imposition connection to the bottom of the non-through hole 61A formed thereby, so that the LED 75 is placed in the non-through hole 61A. It is accommodated and sealed with a transparent synthetic resin 76.
[0005]
Thus, the light emitted from the LED 75 accommodated in the non-through hole 61A is transmitted through the transparent synthetic resin 76, reflected by the gold plating film 64 covered on the inner wall surface of the large diameter portion 63, and non- Radiated from the opening of the through hole 61A. Here, by removing the gold plating film 64 at the lower end portion of the non-through hole 61A that contacts the anode terminal portion 71 and the cathode terminal portion 72, the anode terminal portion 71 and the cathode are interposed via the gold plating film 64. The terminal portion 72 is not electrically short-circuited.
[0006]
[Problems to be solved by the invention]
The above-described conventional reflector 60 is made of plastic and is manufactured as a molded product using a molding die, and it is difficult to increase the size of the molding die due to manufacturing accuracy, structure, and manufacturing cost. Therefore, there is a limit to the external dimensions of the reflector 60 that can be manufactured. Further, since a special molding die is required to increase the adhesion of the gold plating film 64 to the inner wall surface of the non-through hole 61A, the molding die is expensive. Furthermore, since the gold plating film 64 formed on the inner wall surface of the small-diameter portion 62 is removed to form a two-stage molding, there is a problem that the number of processing steps increases.
[0007]
The present invention has been made in view of the above-described conventional problems, and a first object is to enlarge the plate and form it at a low cost while maintaining high accuracy and high quality. The second object is to reduce the number of processing steps by increasing the size.
[0008]
[Means for Solving the Problems]
In order to achieve this object, the invention according to claim 1 provides a first printed wiring in which a through hole for accommodating an LED is provided and a noble metal plating film that reflects light is formed on the inner wall except for the upper and lower end surfaces of the through hole. And a second printed wiring board having the through hole as a non-through hole by adhering to the lower side of the first printed wiring board, and a plurality of the non-through holes are provided in a matrix shape. At least two colors of LEDs are housed in the holes, and a plurality of cathode terminals and common anode terminals for the LEDs are provided on the first layer of the second printed wiring board corresponding to the non-through holes. A plurality of cathode terminal lead wires are provided in parallel with each other on the first layer, and a plurality of common anode terminal lead wires are provided on the second layer of the second printed wiring board. The lead wire for the common anode terminal and the common anode terminal are connected by through-hole plating so as to be orthogonal to the lead-out line .
Therefore, a noble metal plating film such as gold plating, silver plating, rhodium plating or the like can be formed by the same method as the method of forming the pattern wiring of the printed wiring board. Also, the number of plated through holes is reduced to almost half.
[0009]
The invention according to claim 2 includes a step of drilling a through hole in a plate-shaped member, a step of applying through hole plating to the through hole, a step of filling the through hole with a heat-shrinkable filler, A step of heating the shrinkable filler, a step of etching a portion exposed from the heat-shrinkable filler in the plated through hole, a step of removing the heat-shrinkable filler, and a noble metal plating film on the through-hole plated conductor The process of giving.
Therefore, the noble metal plating film can be formed by a method of forming a through hole plating by normal panel plating and a wiring pattern by etching.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an arrangement of patterns in a second printed wiring board constituting a mounting body according to the present invention. FIG. 2 is a plan view showing the arrangement of patterns in the second printed wiring board. FIG. 3 is a cross-sectional view for explaining the first half of the process for producing a printed wiring board used in the display according to the present invention. FIG. 4 is a cross-sectional view for explaining the latter half of the process for producing a printed wiring board. FIG. 5 is an enlarged cross-sectional view showing a main part of the display body according to the present invention. FIG. 6 is a front view of a display body according to the present invention.
[0012]
In FIG. 6, the display body denoted as a whole by reference numeral 1 includes a red LED 20 that emits red and a blue LED 21 that emits blue, which will be described later, on a multilayer printed wiring board 2 for two-color LEDs as a second printed wiring board. A number of two-color LEDs 3 each having a pair of two-color LEDs having different colors are arranged in a matrix.
[0013]
A total of 512 two-color LEDs 3 are provided by arranging 32 rows (m rows) in the X-axis direction and 16 rows (n stages) in the Y-axis direction. As will be described later, these 512 LEDs 3 are selectively made to emit light so that characters, figures and the like are displayed.
[0014]
In FIG. 1, 10 is a red LED cathode terminal formed in a square shape, 11 is a blue LED cathode terminal formed in a square shape, and 12 is a common anode terminal formed in an elongated rectangle common to the red LED 20 and the blue LED 21. is there. A pair of two-color LED terminals 9 is formed by the red LED cathode terminal 10, the blue LED cathode terminal 11, and the common anode terminal 12, and the two-color LED terminal 9 corresponds to the LED 3 described above. 512 are arranged in a matrix. These two-color LED terminals 9 are formed on the first layer of the two-color LED multilayer printed wiring board 2.
[0015]
The feature of the present invention is that, as shown in FIG. 1, a red LED cathode terminal lead wire 13 and a blue LED cathode terminal lead wire 14 are provided in the first layer of the multilayer printed wiring board 2 for two-color LEDs. In the point. That is, as shown in the figure, the second layer of the two-color LED multilayer printed wiring board 2 is provided with a common anode terminal lead-out line 17, and the n common anode terminals 12 arranged in the same column. It extends in the Y-axis direction so as to be positioned below, and is provided m in parallel with the X-axis direction. The common anode terminal lead lines 17 are electrically connected to the common anode terminal lead lines 17m in each column by the common anode terminal 12m in each column and the common anode terminal plating through hole 31m in each column.
[0016]
Thus, the anode plating through hole 31 is provided in the common anode terminal 12, and the plating through hole is not provided in the red LED cathode terminal 10 and the blue LED cathode terminal 11. Is reduced by almost half. For this reason, not only high-density wiring is possible, but the outer shape of the printed wiring board can be reduced by increasing the space for providing the pattern wiring on the second layer of the multilayer printed wiring board 2 for two-color LEDs. Can do. In addition, since it is not necessary to perform pattern wiring so as to bypass the plated through hole, the degree of design freedom in pattern wiring is increased.
[0017]
Further, as shown in FIG. 2, the red LED cathode terminal lead wire 13 and the blue LED cathode terminal lead wire 14 provided in the first layer of the two-color LED multilayer printed wiring board 2 are a pair of two. The two-color LED cathode terminals 10 and 11 forming the color LED terminal 9 are arranged in the direction in which the two-color cathode terminals 10 and 11 are sandwiched. In other words, the blue LED cathode terminal lead wire 14 is led out in the X-axis direction above the two-color LED cathode terminals 10 and 11 in FIG. On the other hand, the red LED cathode terminal lead line 13 is electrically connected to the red LED cathode terminal 10 via an auxiliary lead line 34 extending in the Y-axis direction. The lower part of the terminals 10 and 11 is drawn out in the X-axis direction.
[0018]
As described above, the red LED cathode terminal lead line 13 and the blue LED cathode terminal lead line 14 constitute a pair of two-color LED terminals 9 and the red LED cathode terminal 10 and the blue LED cathode terminal. 11 is drawn in a direction perpendicular to the short side of the rectangle having a short side length B1 and a long side length B2. Therefore, the red LED cathode terminal lead wire 13 and the blue LED cathode terminal lead wire 14 do not increase the dimension in the Y-axis direction, and the printed wiring board can be further downsized.
[0019]
In such a configuration, when a voltage is applied to any one of the m common anode terminal lead lines 17 and a voltage is applied to any one of the n red LED cathode terminal lead lines 13, m The red LEDs 20 (m, n) of the n-stage two-color LEDs 3 in the row emit light. Further, when a voltage is applied to any one of the m common anode terminal lead lines 17 and a voltage is applied to any one of the n blue LED cathode terminal lead lines 14, there are n columns of m columns. The blue LED 21 (m, n) of the two-color LED 3 emits light.
[0020]
Next, the manufacturing method of the printed wiring board which comprises the display body 1 which concerns on this invention is demonstrated using FIG. 3 and FIG.
In FIG. 3A, reference numeral 40 denotes an insulating resin material having copper foils 41 and 41 attached to both surfaces, and a through hole 42 is drilled by a drill. As shown in FIG. 4B, the entire panel is plated by electrolytic copper plating to form a copper plating film 43 on the copper foil 41 and a through-hole plating film 44 on the inner wall surface of the through hole 42.
[0021]
As shown in FIG. 5C, after filling the through-hole 42 with the heat-shrinkable filler 45, the entire insulating resin material 40 is heated and dried from the front and back with a hot air dryer or an infrared dryer. Therefore, the heat-shrinkable filler 45 is also heated, so that the heat-shrinkable filler 45 is solidified. At this time, since the heated heat-shrinkable filler 45 contracts, the height between the upper and lower end faces of the heat-shrinkable filler 45 and the upper and lower end faces of the insulating resin material 40 is reduced as shown in FIG. Unfilled portions 47, 48 of t are formed.
[0022]
Therefore, in FIG. 5E, by performing the entire surface etching, portions other than the portion filled with the heat-shrinkable filler 45 are removed, so the copper plating film is removed at the upper and lower end portions of the through hole 42. The formed portions 47 and 48 are formed. Next, as shown in FIG. 5F, the heat-shrinkable filler 45 is dissolved and removed to leave the copper plating film 49 only on the inner wall surface of the through hole 42.
[0023]
As shown in FIG. 4A, a printed wiring board 55 is manufactured by forming a gold plating film 50 by performing gold plating after performing nickel plating on the copper plating film 49 as a base plating. In this case, by performing nickel plating as a base plating before gold plating, the fine unevenness having a depth of 0.2 to 2.0 μm formed on the surface of the copper plating film 49 is formed by the nickel plating film. It can be flattened to a depth of 0.02-0.08 μm. Therefore, since the expensive gold plating film 50 can be made extremely thin, it is excellent in economic efficiency. Also at this time, portions where the gold plating film 50 is not formed remain in the upper and lower end portions 47 and 48 of the through hole 42.
[0024]
As shown in FIG. 2B, the non-through hole 42A is formed by bonding the printed wiring board 55 formed in this way and the multilayer printed wiring board 2 for two-color LEDs. At this time, the non-through holes 42A are made to correspond to the red LED cathode terminal 10, the blue LED cathode terminal 11 and the common anode terminal 12 so that the printed wiring board is placed on the above-described two-color LED multilayer printed wiring board 2. Overlay 55. Next, the red LED 20 and the blue LED 21 are electrically connected to the red LED cathode terminal 10 and the common anode terminal 12 and the blue LED cathode terminal 11 and the common anode terminal 12 by wire bonding, respectively. As shown in FIG. 5, the red LED 20 and the blue LED 21 connected to the bottom of the non-through hole 42A are sealed with a transparent synthetic resin 52 and fixed on the multilayer printed wiring board 2 for two-color LEDs. 1 is formed.
[0025]
In the display body 1 thus formed, the light that travels straight upward from the light emitted from the red LED 20 and the blue LED 21 is transmitted through the transparent synthetic resin 52 and is radiated as it is from the opening of the non-through hole 42A. Is done. On the other hand, of the light emitted from the red LED 20 and the blue LED 21, the light to be diffused in the left-right direction is transmitted through the transparent synthetic resin 52 and then formed on the inner wall surface of the non-through hole 42A. 50 is reflected, and diffusion is suppressed, and the light is emitted from the opening of the non-through hole 42A.
[0026]
Here, since the gold plating film 50 is not formed at the lower end portion 48 of the non-through hole 42 </ b> A, the common anode terminal 12, the cathode terminals 10, 11 and the wiring pattern do not come into contact with the gold plating film 50. Therefore, there is no electrical short circuit through the gold plating film 50. Further, since the printed wiring board 55 is formed of the insulating resin material 40, the non-through hole 42A and the gold plating film 50 are formed by the same method as the method of forming the plated through hole in the printed wiring board. Therefore, an expensive special molding die for forming a molded product as in the prior art becomes unnecessary.
[0027]
Therefore, not only the manufacturing cost can be reduced, but also a printed wiring board having a large outer dimension can be formed with higher accuracy and higher quality than a molded product made of conventional plastic. Further, by using the heat-shrinkable filler 45, a portion where the gold plating film 50 is not formed is provided at the lower end portion of the non-through hole 42, and is formed by a normal etching process without increasing the processing steps. Therefore, not only can the manufacturing cost be reduced, but the number of processing steps can be greatly reduced.
[0028]
Although the gold film 50 is used as the reflective film, the present invention is not limited to this, and other noble metal plating films such as a silver plating film and a rhodium plating film may be used. In FIG. 3C, the heat shrinkable resin 45 is filled in the through hole 42 and unfilled portions 47 and 48 are formed in FIG. 3D. However, a normal hole filling resin is used for the through hole 42. Then, the unfilled portions 47 and 48 can be formed by overetching 1.5 to 3 times the conventional amount. Further, in FIG. 3E, the entire surface is etched, but pattern wiring can be formed on the front and back of the insulating resin material 40 by performing partial etching.
[0029]
【The invention's effect】
As described above, according to the invention according to claim 1, since the gold plating film can be formed by the same method as the method of forming the through hole in the printed wiring board, not only the manufacturing cost can be reduced but also the outer shape can be reduced. A printed wiring board having a large size can be formed. Further, by reducing the number of through holes, not only high-density wiring is possible, but also the space for providing pattern wiring is increased, so that the outer shape of the printed wiring board can be reduced in size. Further, since it is not necessary to perform pattern wiring so as to bypass the through hole, the degree of design freedom in pattern wiring is increased.
[0030]
Moreover, according to the invention which concerns on Claim 2, not only a manufacturing cost can be reduced, but a processing man-hour does not increase.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an arrangement of patterns in a second printed wiring board constituting a mounting body according to the present invention.
FIG. 2 is a plan view showing an arrangement of patterns on a second printed wiring board constituting the mounting body according to the present invention.
FIG. 3 is a cross-sectional view for explaining the first half of the process for producing a printed wiring board used for the display body according to the present invention.
FIG. 4 is a cross-sectional view for explaining the latter half of the process for producing a printed wiring board used in the display body according to the present invention.
FIG. 5 is an enlarged cross-sectional view showing a main part of a display body according to the present invention.
FIG. 6 is a front view of a display body according to the present invention.
FIG. 7 is a cross-sectional view for explaining a conventional method of manufacturing a printed wiring board.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Display body, 2 ... Multi-layer printed wiring board for 2 color LED, 3 ... 2 color LED, 9 ... Terminal for 2 color LED, 10 ... Cathode terminal for red LED, 11 ... Cathode terminal for blue LED, 12 ... Common anode Terminal: 13 ... Red LED cathode terminal lead wire, 14: Blue LED cathode terminal lead wire, 17 ... Common anode terminal lead wire, 20 ... Red LED, 21 ... Blue LED, 31 ... Anode plating through hole, 42A ... Non-through holes, 44 ... through-hole plating film, 45 ... heat-shrinkable filler, 48 ... part where gold plating is removed, 50 ... gold plating film, 52 ... transparent synthetic resin, 55 ... printed wiring board.

Claims (2)

A first printed wiring board provided with a through hole for accommodating an LED and having a noble metal plating film reflecting light on the inner wall except for the upper and lower end surfaces of the through hole, and an adhesive below the first printed wiring board A second printed wiring board having the through holes as non-through holes, a plurality of the non-through holes are provided in a matrix, and at least two colors of LEDs are accommodated in the non-through holes, and the second printed circuit board is provided. A plurality of cathode terminals for LED and a common anode terminal are provided in a portion corresponding to the non-through hole on the first layer of the wiring board, and a plurality of cathode terminal lead wires are parallel to each other on the first layer. And a plurality of common anode terminal lead lines are provided in the second layer of the second printed wiring board so as to be orthogonal to the cathode terminal lead lines, and the common anode end Display body, wherein use lead wire and the said common anode terminal that is connected by through-hole plating. A step of drilling a through hole in the plate-like member, a step of performing through-hole plating on the through-hole, a step of filling the through-hole with a heat-shrinkable filler, and a step of heating the heat-shrinkable filler, Etching a portion exposed from the heat shrinkable filler in the plated through hole, removing the heat shrinkable filler, and applying a noble metal plating film on the through hole plated conductor, A printed wiring board manufacturing method.

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