TWI699905B - Method for forming soldering pads on a light-emitting diode carrier - Google Patents

Abstract

A method for forming soldering pads on a light-emitting diode carrier includes the steps of: forming a circuit layer on a substrate, the circuit layer having at least one window opening corresponding region, the circuit layer completely covering the underlying substrate in the window opening corresponding region, the window opening corresponding region being consisted of a P-electrode pad, an N-electrode pad and a connection portion between the P and N-electrode pads, and the P and N-electrode pads being not in direct contact with each other; covering the substrate and the circuit layer with a solder mask layer; using a laser engraving machine to emit at least one laser beam toward the solder mask layer at a region corresponding to the at least one window opening corresponding region, thereby forming at least one laser opening where the P and N-electrode pads and the connection portion are no longer covered by the solder mask layer; and removing the connection portion to electrically separate the P and N-electrode pads.

Description

Method for forming welding pad on light-emitting diode carrier board

The present invention relates to a method for manufacturing a circuit board, in particular to a method for forming solder pads on a light emitting diode carrier board.

The conventional light-emitting diode carrier board includes a substrate, a circuit layer and a solder mask. The solder mask covers the substrate and the circuit layer. The solder mask has several windows that expose a part of the circuit layer to allow the LED Surface mount components such as body can be mounted on the carrier board. In the past, the circuit layer of the light-emitting diode carrier board will be pre-formed with soldering pads for the electrical connection of the light-emitting diode chip, and then a solder mask is covered on the circuit layer, and then a laser engraving machine is used on the circuit board Open the window to expose the solder pad.

However, as shown in Figure 1, in the prior art, when the laser opens the window, not only the solder mask will be burned through, but the substrate 10 between the solder pads will also be partially burned away, resulting in light-emitting diodes. The reliability of the carrier board is reduced, and when the substrate is a multilayer board, the burned-off part of the substrate may also cause the dielectric between the layers to be destroyed, resulting in a decrease in yield.

In view of this, the main purpose of the present invention is to provide a method that does not burn out local substrates during the laser windowing process of the light emitting diode carrier board.

In order to achieve the above and other objectives, the present invention provides a method for forming solder pads on a light emitting diode carrier board, which includes the following steps:

The circuit layer is formed on the substrate, and the circuit layer has at least one window-opening corresponding area. The circuit layer completely covers the substrate underneath in the window-opening corresponding area. The window-opening corresponding area is composed of a P electrode pad and a The N pole soldering pad and the connection part between the P and N pole soldering pads are formed, and the P and N pole soldering pads are not in direct contact with each other;

Covering the substrate and the circuit layer with a solder mask;

A laser engraving machine is used to emit at least one laser beam toward the position of the solder mask corresponding to the at least one window opening to form at least one laser window, so that the P and N electrode pads and the connecting portion No longer covered by the solder mask in the laser window; and

The connection part is removed to make the P and N electrode pads electrically independent of each other.

Through the above technical means, when the laser engraving machine emits the laser beam, the corresponding area of the window is completely covered by the circuit layer, so that the energy of the laser beam does not penetrate the substrate. When the subsequent connection part is removed, the P and N electrode pads The area between the substrates can still maintain the original thickness and the surface is flat, and the reliability of the carrier can be maintained.

The following examples illustrate one of the methods of the present invention for forming solder pads on a light emitting diode carrier board, which includes the following steps:

First, please refer to Figures 2 to 4 to form the circuit layer 20 on the substrate 10: select a single-sided or double-sided substrate as the substrate, that is, select a substrate 10 with a copper foil 21 pre-formed on one or both sides as required, and then Electroplating a layer of copper on the copper foil 21 to increase the thickness of the copper layer (as shown in Figure 3), and then image the copper foil and electroplated copper with the circuit image transfer technology to form a circuit layer 20 (as shown in Figure 4); Wherein, the substrate 10 may be a flexible printed circuit (FPC) substrate or a rigid printed circuit board (PCB) substrate; for example, the substrate 10 may be, but not limited to, polyethylene terephthalic acid Polyester (PET) or other polyester film, polyimide film, polyimide film, polypropylene film, polystyrene film or a combination thereof; the circuit layer 20 has at least one window corresponding area 22, the circuit The layer 20 completely covers the substrate 10 underneath in the window corresponding area 22. The window corresponding area 22 consists of a P electrode pad 23, an N electrode pad 24, and the P and N electrode pads. The connecting portion 25 is formed, and the P and N electrode pads 23 and 24 are not in direct contact with each other; in application fields such as backlight modules and light emitting diode displays, a light emitting diode carrier board usually carries a large number of light emitting diodes For bulk chips, the number of pairs of P and N electrode pads will also increase according to the number of light-emitting diode chips, and the contour of the P and N electrode pads can be determined according to requirements;

Next, as shown in Figure 5, the substrate 10 and the circuit layer 20 are covered with a solder mask 30, and the window corresponding area 22 is also covered by the solder mask 30; in a possible embodiment, the solder mask 30 The material is, for example, a heat-hardening solder mask ink or a light-hardening solder mask ink (double liquid type solder mask ink) or its semi-cured dry film, and its components include, for example, solder mask main agent, colorant, and diluent And hardener (Hardener); in a possible implementation, the solder mask is laminated on the substrate and circuit layer in the form of a semi-cured dry film, and then cured by heat curing and/or light curing to form; in other In a possible implementation manner, the solder mask is formed by coating the substrate and the circuit layer by screen printing, and then curing by thermal curing and/or light curing;

Then, as shown in FIG. 6, a laser engraving machine is used to emit at least one laser beam toward the position of the solder resist layer 30 corresponding to the at least one window corresponding area 22 to form at least one laser window 31, The P and N electrode pads 23 and 24 and the connecting portion 25 are not covered by the solder mask 30 in the laser window 31; the laser window 31 can have any preset contour, such as a circular contour ；

Finally, as shown in Figures 7 to 10, remove the connecting portion 25 so that the P and N electrode pads 23 and 24 are electrically independent of each other; in order to remove the connecting portion 25, the corresponding area 22 Laminate a photoresist layer 40 (as shown in Figure 7), and then expose the photoresist layer 40 (through a photomask). Depending on the positive or negative development characteristics of the developer, the photoresist layer 40 corresponds to the connecting portion 25 The area 40A can be one of the exposed area and the unexposed area, and the areas 40B and 40C corresponding to the P and N electrode pads 23 and 24 in the photoresist layer 40 can be the other of the exposed area and the unexposed area. The photoresist layer 40 at the area 40A is removed by a developer to expose the connection part 25 (as shown in Figure 8), and then the connection part 25 not covered by the photoresist layer 40 is removed by dry etching or wet etching. Make the P and N electrode pads 23 and 24 electrically independent of each other (as shown in Figure 9), and finally remove the photoresist layer 40 in the areas 40B and 40C, and a pair of electrically independent P and N electrode pads are produced 23, 24 light-emitting diode carrier board (as shown in Figure 10).

Through the above technical means, when the laser engraving machine emits the laser beam, the corresponding area of the window is completely covered by the circuit layer, so that the energy of the laser beam does not penetrate the substrate. When the subsequent connection part is removed, the P and N electrode pads The area between the substrates can still maintain the original thickness and the surface is flat, and the reliability of the carrier can be maintained.

10: substrate

20: circuit layer

21: Copper foil

22: Window corresponding area

23: P pole pad

24: N pole pad

25: Connection part

30: Solder mask

31: Laser window

40: photoresist layer

40A, 40B, 40C: area

Figure 1 is a schematic diagram of the conventional light emitting diode carrier board after the laser windowing process.

2 to 10 are schematic diagrams of the manufacturing process of one embodiment of the present invention.

22: Window corresponding area

23: P pole pad

24: N pole pad

25: Connection part

30: Solder mask

31: Laser window

Claims (2)

A method for forming solder pads on a light emitting diode carrier board, comprising the following steps: forming the circuit layer on the substrate, the circuit layer having at least one window corresponding area, and the circuit layer is complete in the window corresponding area Covering the substrate underneath, the window corresponding area is composed of a P electrode pad, an N electrode pad, and a connection part between the P and N electrode pads. The P and N electrode pads do not directly contact each other Cover a solder mask on the substrate and the circuit layer; use a laser engraving machine to emit at least one laser beam toward the solder mask corresponding to the at least one window corresponding area, thereby forming at least one laser Open the window so that the P and N electrode pads and the connecting part are no longer covered by the solder mask in the laser window; and remove the connecting part so that the P and N electrode pads are electrically connected to each other Independent; wherein the "remove the connecting portion" means: laminating a photoresist layer in the at least one window corresponding area, and exposing the photoresist layer, wherein the photoresist layer corresponds to the connecting portion The area is one of an exposed area and an unexposed area, and the area of the photoresist layer corresponding to the P and N electrode pads is the other of the exposed area and the unexposed area; the photoresist layer corresponds to the The area of the connection portion is removed to expose the connection portion, and then the connection portion is etched away, and finally the area of the photoresist layer corresponding to the P and N electrode pads is removed. The method for forming solder pads on a light-emitting diode carrier board as described in claim 1, wherein the photoresist layer in the region corresponding to the connecting portion is removed by a developer.

Images