JP5660790B2 - Bare chip mounting surface light emitter and manufacturing method thereof - Google Patents

Description

  The present invention relates to a surface light emitter in which a bare chip is directly mounted on a substrate and a method for manufacturing the same, and more particularly to a bare chip mounting surface light emitter that lights an LED with a commercial power supply (for example, AC 100 V) without using a power supply module.

The inventor of the present application has previously obtained a patent regarding a method of manufacturing a surface light emitter by a chip-on-board method (Patent Document 1).
Such a surface light emitter has advantages such as being able to reduce the weight of a device in which it is incorporated, and being excellent in waterproofness. The LED can be used with an AC of 100 V without using a power supply module that can take advantage of these advantages. A surface illuminator that was lit directly was contemplated.

A conventional lighting device using an LED as a light source incorporates an AC / DC converter (power supply module) that converts alternating current from a commercial power source into direct current in order to operate the LED with direct current.
However, an electrolytic capacitor is used in the power supply module, and this electrolytic capacitor may reach the end of its life before the LED. Also, there is a risk of smoke and fire due to the capacity loss of the electrolytic capacitor. It was.
On the other hand, without using a power supply module, it is possible to directly light an LED with a commercial power supply of AC 100 V by using the rectifying action and light emitting action of the LED, and such a technique has already been disclosed (Patent Document). 2).
However, as mentioned in Patent Document 2, flickering of light emission (flashing) may occur at the time when the polarity of the current (voltage) is reversed (specification, page 7, 3-12). line).

Japanese Patent No. 3993991 Japanese Utility Model Publication No. 03-41390

  Accordingly, the present invention aims to provide a surface light emitter capable of suppressing light emission flickering (flickering) as much as possible based on the previous patent technology and a method for manufacturing the same.

In order to solve the above-mentioned problems, the present invention has a substrate on which a wiring pattern of a bridge rectifier circuit that rectifies alternating current is formed, and electrodes are connected via auxiliary plating and gold plating applied on the wiring pattern, The wiring pattern is connected in series with a quantity of a range that can be lit corresponding to the polarity of the AC power supply, and adjacent to each other in reverse in accordance with the polarity of the AC power supply. The bare chip mounting surface light emitting device includes a bare chip and a printed layer formed excluding a connection portion of the electrode and a coating layer applied to the surface of the substrate .

The coating layer is formed in a lens shape on a pair of bare chips (the invention of claim 1 above).

In order to solve the above-described problems, the present invention is formed by etching a metal foil on a resin substrate into a wiring pattern of a bridge rectifier circuit that rectifies an alternating current, and overlapping auxiliary plating and gold plating on the predetermined wiring pattern. A step of forming a printed layer excluding the connection portion of the bare chip electrode, and a series of bare chips in a range that can be turned on in correspondence with the polarity of the alternating current in the wiring pattern, and the polarity of the alternating current Corresponding to each of the above, a pair of adjacently energized ones connected to each other and bonding the gold plating, and a step of applying to the surface of the substrate by a coating material. in the production method of the body, the coating layer formed by the coating material, characterized in that it is formed on the bare chip to be paired in a lens shape A method for producing a bare chip emitting body (invention of claim 2).

A printed layer is formed except for a step of forming a wiring pattern on a resin substrate, a step of forming auxiliary plating and gold plating on the connection point of the bare chip electrode on the wiring pattern, and a connection point of the bare chip electrode. And a series of bare chips in a range that can be lit in correspondence with the polarity of alternating current, and a pair of elements that are energized in reverse in correspondence with the polarity of alternating current, A method of manufacturing a bare chip mounting surface light emitting device comprising a step of connecting and bonding the gold plating and a step of applying to the surface of the substrate by a coating material .

The invention smell Te, coating layer formed by the co computing material is characterized by being formed on the wiring pattern.

According to the above invention, on the wiring pattern of the bridge rectifier circuit formed on the resin substrate, in series with the number of ranges that can be lit corresponding to the polarity of AC, and inversion energization respectively corresponding to the polarity of AC Since the bare chips of the light emitting diodes are arranged adjacent to each other in pairs, it is difficult to recognize the blinking of the bare chips.
Therefore, a special power supply module for converting the AC power supply to DC becomes unnecessary.

(A)-(c) is a circuit diagram of the wiring pattern used for a bare chip mounting surface light-emitting body. (D) is an operation explanatory diagram of the circuit. It is principal part sectional drawing of the surface light-emitting body using the circuit of FIG. (A), (b) It is an expanded sectional view of FIG. It is process explanatory drawing of a bare chip mounting surface light-emitting body.

The bare chip mounting surface light emitter L (hereinafter abbreviated as “surface light emitter L”) of the present invention is attached to the resin substrate 1 and the resin substrate 1 as shown in FIGS. As a result, the pinhole 10 as the anchor portion is formed in the substrate 1, and the metal foil 2 etched into the wiring pattern 20 of the bridge rectifier circuit BC and the wiring pattern 20 correspond to the polarity of the AC power supply AC. As shown in the figures 32a to 32o, 33a to 33o, 34a to 34o, and 35a to 35o, the numbers of the ranges that can be turned on are inverted and energized respectively in series and corresponding to the polarity of the AC power supply AC. A light emitting diode bare chip 3 to which each electrode 30 is connected is provided adjacent to each other in pairs.
The other electrode 31 of these bare chips 3 is connected to the gold plating 5 on the auxiliary plating 4 of the wiring pattern 20 via the gold wire 6.
When connected between the bare chip 3 and the gold plating 5, the printed layer 7 is formed except for the connection portion of the bare chip 3 and the other electrode 31 of the bare chip 3, and excluding the region to be punched or cut. A coating layer 8 is provided so as to penetrate the pinholes 10 due to the protrusions remaining on the resin substrate 1 by etching the metal foil 2.

  Since the resin substrate (printed substrate) 1 may mount a plurality of bare chips 3 at high density, it is desirable to use a heat-resistant organic resin substrate having excellent heat dissipation performance, specifically, thermal conductivity. A filler-containing phenolic resin substrate is used. An epoxy resin substrate, a glass woven epoxy resin substrate, a glass nonwoven fabric epoxy resin substrate, or the like may be used.

  The metal foil 2 forms the wiring pattern 20. For example, a material having excellent conductivity such as copper, silver, gold, or platinum is used, and an inexpensive copper foil is preferably used. A large number of protrusions 21 are formed in advance on the back surfaces of these metal foils.

  As shown in FIG. 1A, the wiring pattern 20 of the bridge rectifier circuit BC includes input terminals 200 and 201 connected to output terminals AC1 and AC2 from an AC power source AC, and a load (current limiting resistor) R. Are provided with first to fourth arms 204 to 207 connected between output ends 202 and 203 connected to each other. Each arm 204 to 207 is formed so that a plurality of bare chips 3 can be connected in series as will be described later.

  The type of the bare chip 3 is not particularly limited, and red, green, and blue light emitting diodes can be arbitrarily selected. For example, by using a blue bare chip of a GaN-based compound semiconductor that emits a wavelength of 420 to 500 nm and combining with a phosphor as described later, a white light emitting surface light emitter can be produced.

These bare chips 3 are connected in series to the arms 204 to 207 of the wiring pattern 20 in a quantity that can be turned on in accordance with the polarity of the AC power supply AC.
When the forward voltage (excitation voltage) of each bare chip 3 is 3.3 V and the voltage of the AC power supply is 100 V, the number of the ranges in which about 30 bare chips 3 can be turned on.
Therefore, a total of 30 bare chips 3 are connected in series with 15 bare chips (32a to 32o) to the first arm 204 and 15 bare chips (33a to 33o) to the second arm 205. Further, a total of 30 bare chips 3 are connected in series with 15 bare chips (34a to 34o) on the third arm 206 and 15 bare chips (35a to 35o) on the fourth arm 207.

In the above configuration, the bare chips 3 that are respectively reversely energized corresponding to the polarity of the AC power supply AC are the bare chips (32a to 32o) of the first arm 204 and the bare chips (35a to 35o) of the fourth arm 207, Also, the bare chips (33a to 33o) of the second arm 205 and the bare chips (34a to 34o) of the third arm 206 are shown.
Therefore, as a pair, they are connected as close as possible from the input terminals 200 and 201 to the output terminals 202 and 203 for each connection order (for example, bare chips 32a and 35a). Similarly, the bare chips (33a to 33o) are connected as close as possible to the bare chips (34a to 34o).

  The wiring pattern 20 configured as described above can extend the illumination range of the surface light emitter L by being connected in parallel to the AC power supply AC as necessary.

  The auxiliary plating 4 (see FIG. 3) is preferably nickel plating on which a hard film is formed. The auxiliary plating 4 is applied to the wire bonding point pattern portion for the gold wire 6 connecting the electrode 30 of the blue bare chip 3 and the portion connecting the electrode 30 of the blue bare chip 3 by electroless plating.

  The gold plating 5 is formed by electroless plating and is suitable for high-density mounting.

  The gold wire 6 is required to have good ohmic properties, mechanical connectivity, electrical conductivity and thermal conductivity with the electrodes 30 and 31 of the bare chip 3, and specifically, gold, copper, platinum, aluminum And conductive wires using such metals and alloys thereof.

The printed layer 7 is for concealing the wiring pattern 20 and increasing the reflectance of the light emitter, and forms a printed layer of a color suitable for the light emission color.
The printing method of the printing layer 7 is not specifically limited, For example, printing methods, such as silk printing, gravure printing, and offset printing, can be used, Usually, silk printing is performed.

  The coating layer 8 is made of, for example, a rapidly curable epoxy acrylic. Other acrylic resins or epoxy resins may be used.

  As described above, when the blue bare chip 3 is used, the yellow phosphor 9 may be stirred into the coating layer 8 by vacuum degassing and defoamed and mixed. As the yellow phosphor 9, for example, a YAG (YTTRIUM ALUMINUM GARNET) phosphor material or a BOS (BARIUM ORTHO-SILICATE) phosphor material is used. The phosphor is not particularly limited as long as it receives the excitation light of the blue bare chip 3 and shines in white. For example, a phosphor in which red and green are mixed (RG phosphor) may be used.

  In the above configuration, the pinhole 10 of the anchor portion is formed by adhering the metal foil 2 on the resin substrate 1 and pressurizing it, but the anchor portion is previously formed on the substrate of aluminum or the like by sandblasting etc. A wiring pattern may be formed by plating or the like. Alternatively, an anchor may be mechanically formed after an insulator is formed on a substrate such as aluminum and a wiring pattern is formed by plating or the like.

The operation of the surface light emitter L configured as described above is as follows.
When the polarity of the AC power supply AC is AC1 (+) or AC2 (−), the bare chip (33a to 33o) of the second arm 205, the current limiting resistor R and the bare chip (35a to 35o) of the fourth arm 207 from the input terminal 200. A path for passing current through is formed. Accordingly, each bare chip emits light, but the bare chips (32a to 32o) of the first arm 204 and the bare chips (34a to 34o) of the third arm 206 are turned off.
On the other hand, when the polarity of the AC power supply AC is AC1 (−) or AC2 (+), the bare chip (34a to 34o) of the third arm 206, the current limiting resistor R and the bare chip (32a to 32a of the first arm 204) from the input terminal 201. 32o) is formed.
Therefore, each bare chip emits light, but the bare chips (33a to 33o) of the second arm 205 and the bare chips (35a to 35o) of the fourth arm 207 are turned off.
At this time, since each bare chip is paired adjacently, the light emission of the bare chip 32a compensates for the turn-off of the bare chip 35a and the light emission of the bare chip 35a as in the case of the paired bare chips, for example, the bare chips 32a and 35a. Is formed to compensate for the turn-off of the bare chip 32a.
That is, FIG. 1 (d) shows a waveform of one cycle of the frequency of the AC power supply, and shows that the above-described configuration synthesizes in a pair of bare chips. For example, when the AC power supply has a frequency of 50 cycles, a pair of bare chips are lit at a frequency of 100 times the double, and a single light source is formed, and the on / off of each bare chip is recognized. It becomes difficult and continuous light emission becomes possible.

  In the above configuration, the pinhole 10 of the anchor portion is formed by pasting the metal foil 2 on the resin substrate 1 and applying pressure, but the anchor portion is previously formed on a substrate such as aluminum by sandblasting or the like. Alternatively, an insulator may be formed and a wiring pattern may be formed by plating or the like. Alternatively, an anchor may be mechanically formed after an insulator is formed on a substrate such as aluminum and a wiring pattern is formed by plating or the like.

The effect of the surface light emitter L having the above configuration is as follows.
(1) Each bare chip is connected in series according to the AC voltage value, and the pair of bare chips (32a-35a) to (32o-35o) and the bare chips (33a-34a) to (33o-34o) Is formed to compensate for the other light extinction, so that only one light source is formed, and it is difficult to recognize on / off of each bare chip, and continuous light emission is possible.
Therefore, a commercial power supply can be used directly without requiring a special power supply module.
(2) The auxiliary plating 4 protects the resin substrate 1 from being deformed by heat welding and pressure welding by a welding machine applied to the bonding point, and improves bonding reliability. Therefore, it is possible to mount the bare chip 3 on a thin resin substrate (for example, 0.3 mm thick) by interposing the auxiliary plating 4 under the gold plating 5.
(3) By the action of (1), the surface light emitter L having a thickness of 1.3 mm ± 0.1 including the coating layer applied to the surface of the resin substrate 1 can be manufactured.
(4) Further, due to the anchor effect of the pinhole 10 formed in the substrate 1, the adhesion and adhesion of the coating layer 8 to the substrate 1 are enhanced, and the impact resistance, vibration resistance, and waterproof resistance are excellent.
(5) The light emitted from the blue bare chip 3 is converted into white by the phosphor, diffused in the coating layer, emitted from the coating layer, and surface emission is formed.
That is, unlike the configuration in which the LED chips are mounted on the substrate, the bare chips 3 are mounted on the resin substrate 1, and therefore, the bare chips 3 can be mounted at a high density. Moreover, even if the luminance unevenness in the case of the LED chip is about 20 to 30%, it is possible to obtain a uniform surface emission illuminance by correcting the amount of stirring of the phosphor.
(6) Utilizing a rapid-curing epoxy acrylic, it can be applied and cured according to characters and designs.

In the above configuration, a flat coating layer 8 covers a single substrate on which a plurality of bare chips 3 are mounted with high density. A pair of bare chips (32a-35a) to (32o-35o) and bare chips (33a-34a) to (33o-34o) may be formed in a lens shape.
In this case, since the light from the paired chips is diffused and emitted, it is further difficult to recognize on / off of the bare chip.

Further, as shown by the two-dot chain line in FIG. 1 (c), the coating layer 8 may be formed in units of bare chip connection rows.
In this case, the surface light emitter L can be adapted to various lighting devices.

Next, a method for manufacturing the surface light emitter L configured as described above will be described with reference to FIGS.
(A) A metal foil 2 having a large number of protrusions 21 is attached on the resin substrate 1 by biting the protrusions 21 into the resin substrate 1 (FIG. 4A).
That is, an adhesive is applied in advance to the attachment surface of the metal foil 2, and pressure bonding is performed so that the protrusions 21 bite into the resin substrate 1.

(B) The metal foil 2 is formed on the wiring pattern 20 of the bridge rectifier circuit BC (FIG. 4B).
That is, the metal foil 2 is etched to form the wiring pattern 20 of the bridge rectifier circuit BC.
The formation method of the wiring pattern 20 can be performed using a conventionally known technique such as an etched foil method. The pinhole 10 formed by the biting of the protrusion 21 remains on the surface of the resin substrate 1 from which the metal foil has been removed by this etching.

(C) The auxiliary plating 4 and the electroless gold plating 5 are formed on the predetermined wiring pattern 20 so as to overlap (FIG. 4C).
On the wiring pattern 20 adjacent to the wiring pattern 20 to which the bare chip 3 is fixed, the mounting density can be increased by electroless plating or electroless plating, and nickel having a strong film is plated. Next, gold plating 5 is applied on the auxiliary plating layer by electroless plating.

(D) A print layer 7 is formed in a region excluding at least a region where the gold plating 5, bare chip 3, and other elements are arranged (FIG. 4D).
This is because the wiring pattern 20 is concealed, the reflectance of the bare chip 3 is increased, the location of the bare chip 3, the current limiting resistor R, the location of the gold plating 5, etc. are clearly shown, etc. A printing layer of a color suitable for the above is formed by silk printing.
At this time, in the present invention, when the surface light emitter L is divided by secondary processing such as punching or cutting with respect to the surface light emitter L by adjusting the range of the printed layer 7, The printed layer 7 is not formed in the region to be formed.

(E) A number of bare chips 3 in a range that can be turned on in accordance with the polarity of the AC power supply AC are connected in series on the wiring pattern 20 and are reversely energized in accordance with the polarity of the AC power supply AC. Adjacent pairs are connected and bonded to the gold plating (FIG. 4E).
That is, one electrode (for example, the N-side electrode) 30 of the bare chip 3 is directly connected to each arm 204 to 207 of the wiring pattern 20, and the other electrode (for example, the P-side electrode) 31 is brought close to the gold wire 6. Are connected to the gold plating 5 on each of the arms 204 to 207. The electrodes and wiring of each bare chip 3 can be easily connected by wire bonding equipment. In this case, as described above, the auxiliary plating 4 is formed by heat welding and pressure welding by a welding machine applied to the bonding point. Thus, the resin substrate 1 is protected from deformation and bonding reliability is improved.

(F) The coating layer 8 is formed by infiltrating the coating material into the pinholes 10 formed by the protrusions 21 remaining on the resin substrate 1 by the removal of the metal foil 2 (FIG. 4F).

  The coating material is cured using a rapidly curable acrylic resin.

  In the above process, the pinhole 10 of the anchor portion is formed by adhering the metal foil 2 on the resin substrate 1 and pressurizing it, but the anchor portion is previously formed on the substrate of aluminum or the like by sandblasting etc. A wiring pattern may be formed by plating or the like. Alternatively, an anchor may be mechanically formed after an insulator is formed on a substrate such as aluminum and a wiring pattern is formed by plating or the like.

In addition to the above (1) to (6), the effect of the bare chip mounting surface light emitter manufacturing method comprising the above steps is as follows.
(7) There is no need to manufacture the LED chip in a separate process, and the bare chip mounting surface light emitter L can be produced in a single process from mounting to the substrate 1 to coating. In other words, in the past, white LED chips were made by the LED manufacturer, purchased by the lighting equipment manufacturer, and mounted on the board. In the present invention, however, the white surface light emitter can be efficiently processed in a few steps at a time. L can be produced.
(8) By adjusting the amount of stirring of the phosphor 9 with respect to the coating material, the white color of the entire surface light emitter can be changed.
(9) The amount of stirring of the phosphor 9 can be adjusted, and since the bare chip 3 can be mounted with a high density, luminance unevenness can be reduced.

  In addition, an epoxy resin can be used as a coating material, and the curing agent used for this is not particularly limited as long as it exhibits a curing reaction with an epoxy resin, and a known curing agent is used. For example, a phenol resin Or an acid anhydride is preferable. In particular, when an acid anhydride curing agent is used, it is more preferable to use an acid anhydride because the optical properties of the cured product are remarkably improved.

  In addition, conventionally known additives such as antioxidants, colorants, coupling agents, modifiers, light (ultraviolet rays, visible rays, infrared rays) absorbers, fillers, and the like are added to the above resin compositions as necessary. Can be blended.

  In the chip-on-board type surface light emitting body L obtained as described above, the coating layer 8 is in the pinhole 10 left on the resin substrate 1, so that the adhesion to the resin substrate 1 is good. Extremely expensive. For this reason, by using the region where the coating layer 8 has digged into the pinhole 10 and performing secondary processing such as punching or cutting with a press, without causing separation between the resin substrate 1 and the coating layer 8, A surface light emitter L having a desired shape can be obtained.

L Bare chip mounting surface light emitter 1 Resin substrate 10 Pinhole 2 Metal foil 20 Wiring pattern 21 Protrusion 200, 201 Input end 202, 203 Output end 204 First arm 205 Second arm 206 Third arm 207 Fourth arm

3 Bare chip 30 31 Electrode 32a to 32o Bare chip 33a to 33o Bare chip 34a to 34o Bare chip 35a to 35o Bare chip

4 Auxiliary plating 5 Gold plating 6 Gold wire 7 Print layer 8 Coating layer 9 Yellow phosphor

Claims (2)

A substrate on which a wiring pattern of a bridge rectifier circuit that rectifies alternating current is formed;
The electrodes are connected via auxiliary plating and gold plating applied on the wiring pattern, and in series with the wiring pattern in a quantity that can be lit according to the polarity of the AC power source, and the AC power source A pair of bare chips that are connected to each other in pairs, each of which is reversely energized corresponding to the polarity,
Except for the connection point of the electrode, a printed layer to be formed;
Comprising a coating layer applied to the surface of the substrate;
The bare chip mounting surface light emitter , wherein the coating layer is formed in a lens shape on a pair of bare chips . Etching the metal foil on the resin substrate into the wiring pattern of the bridge rectifier circuit that rectifies alternating current;
A process of forming auxiliary plating and gold plating on a predetermined wiring pattern;
Forming a printed layer excluding the connection part of the bare chip electrode;
A series of bare chips in a range that can be lit in correspondence with the polarity of alternating current, and a pair of reversely energized ones corresponding to the polarity of alternating current are connected adjacently to the wiring pattern, and Bonding the gold plating;
In the manufacturing method of the bare chip mounting surface light emitter comprising the step of applying to the surface of the substrate by the coating material,
The method of manufacturing a bare chip mounting surface light emitter, wherein the coating layer formed of the coating material is formed in a lens shape on a pair of bare chips .

Images