WO2019088530A1

WO2019088530A1 - Apparatus and method for sintering conductive material using laser

Info

Publication number: WO2019088530A1
Application number: PCT/KR2018/012425
Authority: WO
Inventors: 배현섭; 김정태
Original assignee: 위아코퍼레이션 주식회사
Priority date: 2017-11-01
Filing date: 2018-10-19
Publication date: 2019-05-09

Abstract

An apparatus and a method for sintering a conductive material using a laser are disclosed. An apparatus for sintering a conductive material, according to an aspect of the present invention, comprises: a laser beam source; a laser resonator capable of selectively outputting a laser beam having two or more different wavelengths by converting a wavelength of a laser beam outputted from the laser beam source; and an optical system for forming the laser beam outputted from the laser resonator into a line beam.

Description

Device and method for sintering conductive material using laser

The present invention relates to an apparatus and a method for sintering a conductive material using a laser.

In order to form a pattern on a substrate in a printed circuit board (PCB) manufacturing process, a method of removing only unnecessary portions by etching is generally used. The etching process is advantageous in that a fine pattern can be realized and a large area can be produced. However, the etching process has a problem that the equipment is expensive and the operation time is long.

Recently, as a method for forming a pattern, a method of printing a pattern using a conductive material and then sintering a conductive material using a laser has been used. For example, a pattern can be formed by printing a pattern using a conductive material containing silver particles using an inkjet printer, irradiating the printed pattern with a laser, and sintering the pattern. Such an ink-jet method has advantages in that a pattern can be formed without complicated processes such as etching, so that the production cost can be reduced and the process time can be shortened.

The laser used for sintering the printed circuit mainly uses a spot beam. The spot beam is obtained by forming a laser beam outputted from a light source on a printed circuit which is a workpiece by using a focusing lens and focusing the laser beam. Since the size of the spot beam is smaller than that of the printed circuit, it takes a long time to scan and sinter the entire surface of the printed circuit.

Further, when a printed circuit is sintered with a laser, the wavelength of a suitable laser beam may be varied depending on the material of the pattern to be sintered. For example, when the material of the print pattern is copper and silver, respectively, the wavelength of the laser beam suitable for sintering may be different. Further, even in the case of a print pattern of the same material, a suitable laser wavelength may be different depending on the state of the print pattern. For example, when a print pattern made of copper is formed, the wavelength of a laser beam suitable for a print pattern that is not completely dried immediately after pattern printing and a print pattern that is completely dried may be different. In particular, when sintering is performed within a short time using the peak absorption wavelength of a material, deformation may be caused in the patterned material and the substrate, which may result in deterioration of durability and conductivity.

SUMMARY OF THE INVENTION Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide an apparatus and a method for reducing sintering time for a conductive material.

Other objects of the present invention will become more apparent through the embodiments described below.

A conductive material sintering apparatus according to one aspect of the present invention includes a laser light source, a laser resonator capable of selectively outputting a laser beam having two or more different wavelengths by changing the wavelength of the laser beam output from the laser light source, And an optical system for forming a laser beam outputted from the laser resonator into a line beam.

The conductive material sintering apparatus according to the present invention may include one or more of the following embodiments. For example, the laser resonator can selectively output the UV laser beam and the IR laser beam.

The laser resonator may comprise a nonlinear medium.

The laser beam transmitted through the beam splitter irradiates the side surface of the workpiece and the laser beam reflected by the beam splitter can irradiate the upper surface of the workpiece .

The light reflected from the beam splitter can be irradiated onto the upper surface of the workpiece after passing through the focusing lens.

And a resistance meter capable of measuring the resistance of the pattern using a pattern formed on the upper surface of the workpiece.

The laser resonator may be disposed on two different sides of the workpiece, respectively. Further, two or more laser resonators may be disposed on one side of the workpiece.

The line beam can be formed smaller than the thickness of the workpiece. In addition, the horizontal and vertical size of the line beam can be adjusted.

According to an aspect of the present invention, there is provided a method of sintering a conductive material, the method comprising: forming a laser beam having a first wavelength using a laser light source; irradiating the pattern with a pattern formed on a workpiece; Changing a wavelength of a laser beam output from the laser light source to a second wavelength using a laser beam source; forming a laser beam having a second wavelength by a line beam; irradiating the laser beam onto a pattern formed on the workpiece; .

In the conductive material sintering method according to the present invention, the line beam having the first wavelength dries the pattern while moving in the first direction, and the line beam having the second wavelength moves in the second direction opposite to the first direction The pattern can be sintered.

The present invention can provide an apparatus and a method for sintering a conductive material using a laser capable of reducing a sintering time for a conductive material.

1 is a view illustrating a process of sintering a pattern of a conductive material sintering apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a state in which a line beam scans a pattern in FIG. 1; FIG.

3 is a view illustrating a sintering apparatus for a conductive material according to a second embodiment of the present invention.

Fig. 4 is a diagram illustrating a state in which the resistance is measured in Fig. 3. Fig.

5 is a diagram illustrating a sintering apparatus for a conductive material according to a third embodiment of the present invention.

6 is a view illustrating a sintering apparatus for a conductive material according to a fourth embodiment of the present invention.

7 is a view illustrating a method of sintering a conductive material according to an embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout the specification and claims. The description will be omitted.

FIG. 1 is a view illustrating a process of sintering a conductive material sintering apparatus 100 according to a first embodiment of the present invention. FIG. 2 illustrates a state in which a line beam 114 scans a pattern in FIG. FIG.

1, the shielding member 122 is not shown for the sake of convenience.

The conductive material sintering apparatus 100 according to the present embodiment is characterized in that it includes a laser resonator 110 capable of outputting different kinds of wavelengths by using one laser light source 116. Therefore, since the conductive material sintering apparatus 100 according to the present embodiment can output different kinds of wavelengths using one laser light source 116, the light source having a wavelength suitable for the material or state of the pattern 108 Can be output and scanned. Accordingly, the conductive material sintering apparatus 100 according to the present embodiment can shorten the processing time, and can improve the pattern characteristics (resistance, etc.) by irradiating a laser beam of a wavelength suitable for the pattern.

The conductive material sintering apparatus 100 according to the present embodiment includes one laser light source 116. The laser light source 116 outputs a laser for sintering the pattern 108. The laser output from the laser light source 116 may be any one of a Diode Pump Solid State (DPSS) laser, a pulsed laser, a CW (continuous wave) laser, or an Nd: YAG laser. The wavelength of the laser output from the laser light source 116 may correspond to not less than 500 nm and not more than 1,550 nm. Further, the energy of the laser output from the laser light source 110 may correspond to 100 w / cm 2 or more and 10,000 w / cm 2 or less.

The conductive material sintering apparatus 100 according to the present embodiment includes a laser resonator 110. The laser resonator 110 changes the wavelength and frequency of the laser beam output from the laser light source 116 so that a laser beam having a plurality of wavelengths can be output using one laser light source 116.

The laser resonator 110 may use a nonlinear optical medium for changing the frequency of the laser beam. The nonlinear medium is, for example, KTP (Potassium Titanyl Phosphate), which generates a second harmonic generation which doubles the frequency of the incident beam and halves the wavelength. Therefore, when the wavelength of the fundamental wave incident on the nonlinear medium is 1064 nm, the wavelength of the second harmonic wave passing through the nonlinear medium can be 532 nm, and the phase conjugation method of matching the phase velocities of the two waves, Can be equal.

The nonlinear medium used by the laser resonator 110 may be a BBO (Beta Barium Borate) crystal or an LBO (Lithium Triborate) crystal. Such BBO crystals or LBO crystals can be used to generate the third harmonic generation (UV series).

The laser resonator 110 can change the wavelength of the laser beam emitted from one laser light source 116 to two or more different wavelengths and selectively output each of the wavelengths. In FIG. 1, the laser resonator 110 can selectively generate and output three different wavelengths (for example, 1030 nm of IR series, 515 nm of visible light series, and 343 nm of UV series).

The wavelength of the laser beam that can be output from the laser resonator 110 can be changed according to the material and condition of the pattern 108 to be processed. For example, as illustrated in FIG. 1, since a conductive material is fluidized to a certain degree immediately after printing on the side surface 104 of the workpiece 102, a laser beam having a wavelength of 1030 nm corresponding to the IR series It is possible to scan the printed pattern 108 in a first direction (from left to right in FIG. 1) by changing the wavelength. As a result, the pattern 108 can be dried or hardened.

After drying or hardening of the pattern 108 is completed, the laser resonator 110 is changed to a laser beam having a wavelength of 343 nm which is a UV system, and the dried pattern 108 is moved in the second direction (right to left direction in FIG. 1) Can be scanned. As a result, the pattern 108 can be completely sintered.

Conventionally, a conductive material is printed, dried using an oven or the like, and then sintered using a laser beam. However, since the conductive material sintering apparatus 100 according to the present embodiment can perform both the drying (hardening) and sintering of the conductive material, the processing time and cost can be reduced.

The detailed configuration of the laser resonator 110 is described in Korean Patent Registration No. 120728 and Japanese Patent Laid-Open Publication No. 2008-058947, and therefore a detailed description thereof will be omitted.

The conductive material sintering apparatus 100 according to the present embodiment includes an optical system 120. The optical system 120 forms the laser beam output from the laser resonator 110 as a line beam 114. The beam shape of the line beam 114 may be formed in a range of 1: 1 to 10: 1. In particular, the beam shape of the line beam 114 may be formed to be 2: 1 or more, such as 2 mm in length and 1 mm in width.

The length of the line beam 114 may be longer than the pattern 108 to be sintered. Therefore, since the line beam 114 can cover the entire surface of the pattern 108, the pattern 108 can be dried or sintered by a single irradiation. Of course, the length of the line beam 114 can be determined corresponding to the length of the pattern 108 to be sintered.

Since the beam uniformity of a typical spot laser is Gaussian, the center and outer portions of the beam have different beam energies. In order to uniformly sinter the sample, the energy must have a uniform shape so that the sintering of the conductive material such as the metal ink can be uniformly performed irrespective of the position of the sample, and uniform electrical resistance can be produced. The shape of the line beam proposed in this application also exhibits a uniform beam uniformity of 80% or more and is measured and managed by a beam profiler or the like. If it is less than 80%, there is a difference in sintering degree of the metal ink depending on the position of the sample, so that a difference in electric resistance characteristics may occur by more than 50%.

A beam homogenizer (not shown) may be provided to increase the energy uniformity of the laser line beam.

The workpiece 102 may correspond to a display panel and the pattern 108 may be formed on a side 104 of the display panel. The pattern 108 may be formed on the side surface 104 of the workpiece 102 by printing or the like.

The conductive material may correspond to one of a metal ink, a metal paste, and a metal powder. The metal ink and the metal powder may include at least one conductive material such as copper (Cu), silver (Ag), gold (Au), and nickel (Ni)

The conductive material may be formed to a thickness of 0.1 or more and 20 占 퐉 or less. If the conductive material is formed with a thickness of less than 0.1 占 퐉, the workpiece corresponding to the lower portion of the pattern may be damaged. In addition, when the thickness of the conductive material exceeds 20 탆, sintering may not be performed properly due to defects such as bubbling even when the laser beam is irradiated.

The pattern 108 may be formed by patterning a conductive material using a patterning process such as pad printing, screen printing, metal mask printing, inkjet printing, gravure printing, offset printing ). &Lt; / RTI > Since the pattern 108 has a certain degree of fluidity immediately after printing, it is possible to perform drying (hardening) by using a laser. In this case, the wavelength of the laser beam used may correspond to 1030 nm corresponding to the IR series have.

2, since the line beam 114 is formed longer than the pattern 108, in order to prevent the other part of the workpiece 102 from being damaged by the line beam 114, . The shielding member 122 may be formed of a material that does not transmit the laser line beam 114 but disperses or scatters most of the laser line beam 114. For example, the shielding member 122 can be manufactured by chemically etching the surface of a substrate made of quartz through which a laser beam is transmitted, or by forming fine irregularities on the surface by sandblasting. It is possible to prevent the line beam 114 from being damaged by the shielding member 122 other than the portion to be sintered by the workpiece 102. [

A polarizer film may be attached to the upper surface or the lower surface of the work 102. If the line beam 114 is larger than the thickness of the workpiece 102, the polarizing film may be damaged by the line beam 114. Therefore, the length of the line beam 114 can be made smaller than the thickness of the workpiece 102 such as the display panel.

The line beam 114 may have a rectangular shape. The horizontal and vertical size of the line beam 114 can be adjusted. For example, the horizontal and vertical sizes of the line beam 114 can be adjusted by adjusting the arrangement intervals of lenses (not shown) provided in the optical system 120. [

The tact time for sintering can be adjusted by automatically adjusting the length of the line beam 114 in the transverse direction. In addition, by adjusting the longitudinal length of the line beam 114 automatically, it is possible to cope with a change in the glass thickness of the panel corresponding to the workpiece 102. [

The shielding member 122 may be disposed along the moving direction of the line beam 114 (the direction of the arrow in FIG. 2) and may be disposed at regular intervals with respect to both ends of the pattern 108. Further, the shielding member 122 may be disposed at the upper and lower portions of the pattern 108, respectively, but may be disposed only at one side of the upper portion or the lower portion. By using such a shielding member 122, the trouble of adjusting the size of the line beam 114 corresponding to the size of the pattern 108 can be solved.

FIG. 3 is a view illustrating a conductive material sintering apparatus 200 according to a second embodiment of the present invention, and FIG. 4 is a diagram illustrating a state in which a resistance is measured using the resistance meter 150 in FIG.

3 to 4, the conductive material sintering apparatus 200 according to the second embodiment can simultaneously sinter the pattern 108 formed on the upper surface 106 as well as the side surface 104 of the workpiece 102 . The conductive material sintering apparatus 200 according to the second embodiment has the same structure as the conductive material sintering apparatus 100 according to the first embodiment except that it has a beam splitter 130 for partially reflecting the laser beam .

The beam splitter 130 transmits a part of the line beam output from the optical system 120 and reflects the other. The line beam transmitted through the beam splitter 130 can dry or sinter the pattern 108 formed on the side surface 104 of the workpiece 102. [ In addition, the line beam reflected by the beam splitter 130 can dry or sinter the pattern 108 formed on the upper surface 106 of the workpiece 102. The line beam reflected by the beam splitter 130 is focused on the pattern 108 by the focusing lens 136 via the

reflection lenses

132 and 134.

In the process of forming the conductive material on the side surface 104 of the workpiece 102 by printing or the like, the conductive material may be partially applied to the upper surface 106 and / or the lower surface (not shown). As such, the conductive material partially applied to the upper surface 106 and / or lower surface of the workpiece 102 needs to be dried and / or sintered. The conductive material sintering apparatus 200 according to the present embodiment does not use an optical system 120 for forming a separate laser light source or line beam in order to dry and / or sinter a conductive material formed on the upper surface of the workpiece 102 , And a beam splitter (130) is used to partially distribute the line beam.

Approximately 98% of the laser beam output from the optical system 120 can be transmitted through the beam splitter 130 to dry and / or sinter the side 104 and the remaining 2% can be reflected from the beam splitter 130 106) or the lower surface can be dried and / or sintered. The pattern 108 formed on the upper surface 106 of the workpiece 102 is focused by the focusing lens 136 because the pattern 108 formed on the upper surface 106 of the workpiece 102 is smaller in size than the pattern 108 formed on the side surface 104, Can be used.

Referring to FIG. 4, the conductive material sintering apparatus 200 according to the present embodiment may include a resistance meter 150. The resistance measuring device 150 can measure the resistance of the pattern 108 after the sintering is completed while making electrical contact with the upper surface 106 of the workpiece 102 and the pattern 108 formed on the lower surface.

5 is a diagram illustrating a conductive material sintering apparatus 300 according to a third embodiment of the present invention.

5, the conductive material sintering apparatus 300 according to the third embodiment of the present invention is characterized in that an optical system 120 is provided at each of two different side surfaces 104 of the workpiece 102 . By disposing the optical system for outputting the laser line beam 114 on the x and y axes as described above, the conductive material sintering apparatus 300 according to the present embodiment can simultaneously form the two side surfaces 104 of the workpiece 102 Drying or sintering can be performed, thereby reducing the processing time. Each optical system 120 can operate inter-operatively or independently. In addition, each optical system 120 may share one laser light source 116 and one laser resonator 110. [

6 is a diagram illustrating a conductive material sintering apparatus 400 according to a fourth embodiment of the present invention.

6, the conductive material sintering apparatus 400 according to the fourth embodiment of the present invention includes two or more optical systems 120 corresponding to one side surface 104 of the workpiece 102 . That is, one side 104 of the workpiece 102 may be processed by two or more optical systems 120 simultaneously or sequentially. In this manner, the processing time can be reduced by disposing two or more optical systems 120 that output the laser line beam 114 on one side surface 104. [

7, a conductive material sintering method is a method of sintering a conductive material using one laser light source 116, in which a laser beam having a first wavelength is formed into a line beam 114, Irradiating the formed pattern (108) and drying it; changing the wavelength of the laser beam output from the laser light source (116) from the first wavelength to the second wavelength using the laser resonator (110) And then irradiating the pattern 108 formed on the workpiece 102 and sintering the pattern.

1, a laser beam of a first wavelength (for example, 1030 nm) corresponding to an infrared ray is scanned in a first direction (left to right direction) with respect to a pattern 108 formed by printing a conductive material The pattern 108 is dried (hardened). As a result, the pattern 108 having fluidity is dried and partly cured to remove fluidity.

After the drying of the pattern 108 is completed, the wavelength of the laser beam is changed to a second wavelength (for example, 343 nm) different from the first wavelength by using the laser resonator 110. The laser beam of the second wavelength is scanned in a second direction opposite to the first direction (from right to left in FIG. 1) to sinter the pattern 108.

As described above, in the conductive material sintering method according to the present embodiment, since both drying and sintering of the pattern can be performed using one laser light source and the laser resonator 110, the process time and cost can be reduced .

While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

Claims

One laser light source;

A laser resonator capable of selectively outputting a laser beam having two or more different wavelengths by changing a wavelength of the laser beam output from the laser beam source;

And an optical system for forming the laser beam outputted from the laser resonator into a line beam.
The method according to claim 1,

Wherein the laser resonator is capable of selectively outputting a UV laser beam and an IR laser beam.
The method according to claim 1,

Wherein the laser resonator comprises a nonlinear medium.
The method according to claim 1,

Further comprising a beam splitter through which a laser beam outputted from the optical system enters,

Wherein the laser beam transmitted through the beam splitter irradiates the side surface of the workpiece, and the laser beam reflected by the beam splitter irradiates the upper surface of the workpiece.
5. The method of claim 4,

Wherein the beam reflected by the beam splitter is irradiated onto an upper surface of the workpiece after passing through a focusing lens.
5. The method of claim 4,

Further comprising a resistance meter capable of measuring a resistance of the pattern using a pattern formed on an upper surface of the workpiece.
The method according to claim 1,

Wherein the laser resonator is disposed on two different sides of the workpiece.
The method according to claim 1,

Wherein at least two laser resonators are disposed on one side of the workpiece.
The method according to claim 1,

Wherein the line beam is formed to be smaller than a thickness of the workpiece.
The method according to claim 1,

Wherein a size of the line beam in the horizontal and vertical directions is adjustable.
In the conductive material sintering method using one laser light source,

Forming a laser beam having a first wavelength into a line beam, irradiating the pattern on the workpiece, and drying the pattern; And

Changing a wavelength of the laser beam output from the laser light source from the first wavelength to the second wavelength using a laser resonator;

Forming a laser beam having the second wavelength into a line beam, and irradiating and sintering the pattern formed on the workpiece.
12. The method of claim 11,

The line beam having the first wavelength is moved in the first direction to dry the pattern,

And the line beam having the second wavelength is moved in a second direction opposite to the first direction to sinter the pattern.