TWI837666B - Lighting board and lighting board manufacturing method - Google Patents

Abstract

A lighting board includes a substrate, a conductive trace, a sintered nano-metal layer, a soldering layer, and a light-emitting part. The conductive trace is located on the substrate and has a pad area. The sintered nano-metal layer is located on the pad area. The soldering layer is located on the sintered nano-metal layer. The light-emitting part is fixed on the soldering layer. A lighting board manufacturing method includes the following steps: providing a substrate, forming a conductive trace on the substrate, forming a sintered nano-metal layer on a pad area of the conductive trace, forming a layer of solder paste, disposing a light-emitting part on the layer of solder paste, and performing a reflow soldering on the layer of solder paste.

Description

Light board and light board manufacturing method

The present invention relates to a lamp panel and a manufacturing method thereof, and more particularly to a lamp panel using a sintered nanometal layer as a solder pad and a manufacturing method thereof.

Some illuminated keyboards use flexible printed circuits (FPC) to carry light-emitting diodes (LEDs) as their backlight source. The general FPC manufacturing process is to form copper lines on a polymer substrate, and then solder the LEDs to the copper lines to form a light board. Since the copper line manufacturing process uses a wet yellow light etching process, the process steps are complicated, resulting in high process and material costs.

In view of the problems in the prior art, one object of the present invention is to provide a lamp panel that uses a sintered nanometal layer on its pad area to facilitate the connection between the soldering layer and the pad area.

According to the present invention, a light panel comprises a substrate, a wire, a sintered nanometal layer, a welding layer and a light-emitting element. The wire is located on the substrate and has a welding pad area. The sintered nanometal layer is located on the welding pad area. The welding layer is located on the sintered nanometal layer. The light-emitting element is fixed on the welding layer. In practice, by selecting the material of the sintered nanometal layer, the welding layer can contain a reactant with the sintered nanometal layer, which is more conducive to the sintered nanometal layer to facilitate the connection between the welding layer and the welding pad area.

Another object of the present invention is to provide a method for manufacturing a light panel, using a sintered nanometal layer on its pad area, which can be stably connected to the solder paste.

According to a method for manufacturing a light panel of the present invention, the steps include: providing a substrate; forming a wire on the substrate, the wire having a solder pad area; forming a sintered nanometal layer on the solder pad area; forming a solder paste layer on the sintered nanometal layer; placing a light-emitting element on the solder paste layer; and reflowing the solder paste layer. In practice, by selecting the material of the sintered nanometal layer, the solder paste layer can react with the sintered nanometal layer during reflow, which is more conducive to the connection between the solder layer formed by the solder paste layer and the sintered nanometal layer.

The advantages and spirit of the present invention can be further understood through the following detailed description of the invention and the attached drawings.

Please refer to FIG. 1. A lamp panel 1 according to a first embodiment includes a substrate 12, two wires 14, two sintered nanometal layers 16, two welding layers 18 and a light-emitting element 20. The wires 14 are located on the substrate 12. Each wire 14 has a welding pad area 142. The two sintered nanometal layers 16 are respectively located on the two welding pad areas 142. The two welding layers 18 are respectively located on the two sintered nanometal layers 16. The light-emitting element 20 (for example but not limited to a light-emitting diode) is fixed on the two welding layers 18. The two wires 14 can provide power to the light-emitting element 20 and control its operation. In practical applications, the light board 1 can be applied to a light-emitting keyboard, for example, its backlight source is made of the light board 1 structure.

In the present embodiment, the wire 14 includes a cured silver paste, for example, the wire 14 is formed by printing the silver paste on the substrate 12 and then curing it by heating, but the practice is not limited thereto. The substrate 12 may be, but is not limited to, a polymer substrate of polyethylene terephthalate (which can withstand temperatures of 150 degrees Celsius to 170 degrees Celsius), polyimide, bismaleimide triazine or polymethyl methacrylate. The substrate 12 may also be an IC substrate, such as a BT resin (bismaleimide triazine resin) substrate, a BT-like substrate, an ABF (Ajinomoto Build-up Film) substrate, an MIS (Molded Interconnect Substrate) substrate, etc. In practice, the thickness of the conductive line 14 can be designed to be in the range of 2 micrometers to 30 micrometers.

The sintered nanometal layer 16 includes a plurality of sintered metal nanoparticles, such as but not limited to a plurality of sintered silver nanoparticles, sintered copper nanoparticles, sintered nickel nanoparticles, sintered gold nanoparticles or sintered tin nanoparticles. For example, the sintered nanometal layer 16 is formed by printing a slurry of metal nanoparticles on the pad area 142 and then sintering at a low temperature, wherein the sintered nanometal layer 16 includes a plurality of sintered necks. The sintered nanometal layer 16 can have a good bonding with the pad area 142 of the wire 14. In practice, for example, the particle size of the metal nanoparticles can be in the range of 10 nm to 1000 nm, and for another example, the average particle size of the metal nanoparticles can be in the range of 50 nm to 800 nm. The thickness of the sintered nanometal layer 16 can be designed to be in the range of 0.5 μm to 30 μm.

The soldering layer 18 can be realized by solder paste reflow. By properly selecting the composition of the solder paste and the sintered nanometal layer 16, the solder paste will react with the sintered nanometal layer 16 during reflow to form a copolymer, which can increase the bonding strength between the soldering layer 18 and the sintered nanometal layer 16. In practice, the soldering layer 18 can include tin-bismuth copolymer, tin-bismuth-silver copolymer, or tin-silver-copper copolymer. The thickness of the soldering layer 18 can be designed to be in the range of 2 microns to 50 microns.

Please refer to FIG. 2, which shows a lamp board manufacturing method according to a second embodiment. To simplify the explanation, the manufacturing of the aforementioned lamp board 1 is taken as an example; however, in practice, the aforementioned lamp board 1 is not limited to being manufactured using this lamp board manufacturing method. The relevant descriptions of the components of the aforementioned lamp board 1 are also applicable here and are not repeated here. As shown in step S100 in FIG. 2, the lamp board manufacturing method provides a substrate 12, as shown in FIG. 3. As shown in step S102, the lamp board manufacturing method forms two wires 14 on the substrate, as shown in FIG. 4. Among them, the wire 14 has a solder pad area 142. In practice, step S102 can be achieved by first using silver slurry (for example, prepared from silver or its compounds, flux, adhesive and diluent) to form a silver slurry circuit on the substrate 12 (for example, by printing, wherein the outline of the silver slurry circuit is in principle the same as the outline of the wire 14), and then curing the silver slurry circuit (for example, but not limited to, baking at a temperature in the range of 80 to 250 degrees Celsius), thereby forming the wire 14 on the substrate 12.

As shown in step S104 of FIG. 2 , the lamp panel manufacturing method forms a sintered nanometal layer 16 on the pad area 142 as a pad, as shown in FIG. 5 . The sintered nanometal layer 16 covers the entire corresponding pad area 142 . In practice, step S102 can be achieved by first using a slurry of metal nanoparticles to coat a nanometal layer on the pad area 142 (for example, by printing, wherein the outline of the nanometal layer is in principle the same as the outline of the sintered nanometal layer 16), sintering the nanometal layer (for example, the sintering temperature can be set in the range of 100 degrees Celsius to 300 degrees Celsius), and then forming a sintered nanometal layer 16 on the pad area 142. In addition, in practice, the nanometal layer includes a plurality of metal nanoparticles, such as but not limited to a plurality of silver nanoparticles, copper nanoparticles, nickel nanoparticles, gold nanoparticles or tin nanoparticles. In practice, for example, the particle size of the metal nanoparticles can be in the range of 10 nanometers to 1000 nanometers, and for another example, the average particle size of the metal nanoparticles can be in the range of 50 nanometers to 800 nanometers.

As shown in step S106 of FIG. 2, the lamp board manufacturing method forms a solder paste layer 19 (e.g., including flux and tin or tin alloy powder) on the sintered nanometal layer 16, as shown in FIG. 6. Next, as shown in step S108 of FIG. 2, the lamp board manufacturing method places a light-emitting element 20 on the solder paste layer 19 of the two sintered nanometal layers 16, as shown in FIG. 7. Thereafter, as shown in step S110 of FIG. 2, the lamp board manufacturing method performs reflow on the two solder paste layers (or the entire semi-finished lamp board 1) (e.g., the reflow temperature can be set within a range of 100 degrees Celsius to 270 degrees Celsius). After reflow, the lamp board 1 is completed (see Figure 1).

In addition, please refer to FIG. 8, which is a SEM image of a portion of a lamp panel 1 manufactured according to the lamp panel manufacturing method. The solder paste layer 19 forms a solder layer 18 after reflow. By properly selecting the composition of the solder paste and the sintered nanometal layer 16, during reflow, the solder paste layer 19 will react with the sintered nanometal layer 16 to form a copolymer (such as the interface metal copolymer layer 182 in the figure, such as tin-silver-copper copolymer), which can increase the bonding strength between the solder layer 18 and the sintered nanometal layer 16.

As described above, in the light board 1, the sintered nanometal layer 16 has a good bonding with the pad area 142 of the wire 14. The sintered nanometal layer 16 can be used as a pad, so that the welding layer 18 can be electrically connected to the wire 14 through the sintered nanometal layer 16. In this way, the wire 14 of the light board 1 can be formed in a simple way, such as printing a silver paste line and curing it. Compared with the current etching process for making the line on the FPC, this has the advantages of simple process, low process and material cost. The above is only a preferred embodiment of the present invention. All equal changes and modifications made according to the scope of the patent application of the present invention should be covered by the present invention.

1: Light board 12: Substrate 14: Wire 142: Solder pad area 16: Sintered nanometal layer 18: Solder layer 182: Interface metal co-compound 19: Solder paste layer 20: Light-emitting element S100, S102, S104, S106, S108, S110: Implementation steps

FIG. 1 is a cross-sectional view of a lamp panel according to a first embodiment. FIG. 2 is a flow chart of a lamp panel manufacturing method according to a second embodiment. FIG. 3 is a schematic diagram of a substrate provided according to the lamp panel manufacturing method. FIG. 4 is a schematic diagram after forming a wire on the substrate according to the lamp panel manufacturing method. FIG. 5 is a schematic diagram after forming a sintered nanometal layer on the pad area of the wire according to the lamp panel manufacturing method. FIG. 6 is a schematic diagram after forming a solder paste layer on the sintered nanometal layer according to the lamp panel manufacturing method. FIG. 7 is a schematic diagram after placing a light-emitting element on the solder paste layer according to the lamp panel manufacturing method. FIG. 8 is a SEM image of the lamp panel after reflow according to the lamp panel manufacturing method.

1: Light board

12: Substrate

14: Wire

142: Solder pad area

16: Sintered nanometal layer

18: Welding layer

20: Luminous parts

Claims (19)

A light panel includes: a substrate; a wire located on the substrate, the wire having a pad area; a sintered nanometal layer located on the pad area; a soldering layer located on the sintered nanometal layer; and a light-emitting element fixed on the soldering layer. The light panel as described in claim 1, wherein the sintered nanometal layer comprises sintered silver nanoparticles, sintered copper nanoparticles, sintered nickel nanoparticles, sintered gold nanoparticles or sintered tin nanoparticles. A light panel as described in claim 1, wherein the sintered nanometal layer comprises a plurality of sintered metal nanoparticles, and the particle size of the plurality of metal nanoparticles is in the range of 10 nm to 1000 nm. A light panel as described in claim 1, wherein the sintered nanometal layer comprises a plurality of sintered metal nanoparticles, and the average particle size of the plurality of metal nanoparticles is in the range of 50 nm to 800 nm. A light panel as described in claim 1, wherein the sintered nanometal layer comprises a plurality of sintered necks. A light panel as described in claim 1, wherein the substrate is a polymer substrate of polyethylene terephthalate, polyimide, dimaleimide triazine or polymethyl methacrylate. A light board as described in claim 1, wherein the substrate is an IC carrier. A lamp panel as described in claim 1, wherein the solder layer comprises a tin-bismuth copolymer, a tin-bismuth-silver copolymer or a tin-silver-copper copolymer. A light panel as described in claim 1, wherein the wire comprises solidified silver slurry. A light panel as described in claim 1, wherein the thickness of the wire is in the range of 2 microns to 30 microns. A light panel as described in claim 10, wherein the thickness of the sintered nanometal layer is in the range of 0.5 microns to 30 microns. A lamp panel as described in claim 11, wherein the thickness of the welding layer is in the range of 2 microns to 50 microns. A method for manufacturing a light panel comprises the following steps: (a) providing a substrate; (b) forming a wire on the substrate, the wire having a solder pad area; (c) forming a sintered nanometal layer on the solder pad area; (d) forming a solder paste layer on the sintered nanometal layer; (e) placing a light-emitting element on the solder paste layer; and (f) performing reflow on the solder paste layer. A method for manufacturing a light panel as described in claim 13, wherein step (b) is implemented by the following steps: Using silver slurry to form a silver slurry circuit on the substrate; and Curing the silver slurry circuit to form the conductor on the substrate. The method for manufacturing a light panel as described in claim 13, wherein step (c) is implemented by the following steps: coating a nanometal layer on the pad area; and sintering the nanometal layer to form the sintered nanometal layer. A method for manufacturing a light panel as described in claim 15, wherein the sintering temperature is in the range of 100 degrees Celsius to 300 degrees Celsius. A method for manufacturing a light panel as described in claim 15, wherein the nanometal layer comprises silver nanoparticles, copper nanoparticles, nickel nanoparticles, gold nanoparticles or tin nanoparticles. A method for manufacturing a light panel as described in claim 15, wherein the nanometal layer comprises a plurality of metal nanoparticles, and the particle size of the plurality of metal nanoparticles is in the range of 10 nanometers to 1000 nanometers. A method for manufacturing a light panel as described in claim 15, wherein the nanometal layer comprises a plurality of metal nanoparticles, and the average particle size of the plurality of metal nanoparticles is in the range of 50 nanometers to 800 nanometers.

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