JP4397139B2 - Conductive bump manufacturing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is a manufacturing process of the multilayer wiring substrate, to a manufacturing apparatus for conducting van flop that is used when transferring a conductive bump made of conductive paste on a copper foil.
[0002]
[Prior art]
Multi-layer wiring boards are becoming increasingly denser and more simplified in manufacturing processes, but more than that, improvements in quality and productivity are desired.
As an example of the multilayer wiring board 28 having a high density, the one shown in FIG. 5 is known.
In order to manufacture such a multilayer wiring board 28, as shown in FIG. 3, the central insulating core substrate 20, the insulating prepreg 22 disposed on both sides of the insulating core substrate 20, A copper foil 23 disposed outside the insulating prepreg 22 is used.
[0003]
A wiring pattern 21 is previously formed on at least one of the surfaces of the insulating core substrate 20, in this example, on both surfaces. On one surface of the wiring pattern 21, conductive bumps 24 formed in a conical shape by printing and drying a conductive paste so as to correspond to the wiring pattern 21 of the corresponding insulating core substrate 20 are provided. ing.
[0004]
An insulating prepreg 22 and a copper foil 23 provided with the conductive bumps 24 are sequentially laminated on the wiring patterns 21 on both surfaces of the insulating core substrate 20 thus formed, and pressed while heating. Then, since the insulating prepreg 22 is in a semi-cured state with the insulating resin infiltrated into the base material, it is temporarily softened by heating, and the conductive bumps 24 of the copper foil 23 as shown in FIG. However, it penetrates the insulating prepreg 22 and is crimped and electrically connected to the wiring pattern 21 at the corresponding position of the insulating core substrate 20. When the insulating prepreg 22 is heated, the insulating resin is once melted and then cured, so that the insulating prepreg 22 is fixed to the insulating core substrate 20 in a state of having both the insulator layer and the adhesive layer.
Unnecessary portions of the laminated copper foil 23 on the outer surface are removed by a normal exposure process or other electrochemical process to form a multilayer wiring board 28 having a wiring pattern 25 as shown in FIG. .
[0005]
Since the conductive bumps 24 constituting the multilayer wiring board 28 are for electrical connection between the wiring patterns 21 and 25, if the height and size of the conductive bumps 24 are uneven, poor contact is obtained. As a result, the quality of the product is degraded. For this reason, it is essential that the aspect ratio (ratio of transfer area and paste height) is high and the height is constant. In addition to the fact that the transfer amount of the conductive paste is as large as possible, there has been a demand for a highly accurate manufacturing apparatus for the conductive bump 24 in which there is no variation in the height of the conductive bump 24.
[0006]
At the time of manufacturing the multilayer wiring board 28 as described above, a screen printing method as shown in FIG. 6 was employed to form the conical conductive bumps 24 on the copper foil 23 as shown in FIG. . In this method, first, a printing plate 31 having a large number of paste discharge holes 30 formed on a thin metal plate having a thickness of about 0.5 mm is prepared, and a conductive paste 32 is placed on the printing plate 31. By sliding the squeegee 33 while pressing it with a plate-like squeegee 33 made of rubber, the conductive paste 32 is pushed out of the paste discharge hole 30 and placed on the flat table 34. The conductive bumps 24 are formed by being transferred with adhesive force.
[0007]
In such a conventional method, transfer is performed to the copper foil 23 due to the viscosity of the conductive paste 32. Therefore, the transfer amount of the conductive paste 32 transferred to the copper foil 23 depends on the degree of the viscosity. Even if a paste with high viscosity was selected to increase the transfer amount, there was a limit in physical properties, and the intended purpose could not be achieved only by the degree of viscosity.
[0008]
Even if a high aspect ratio can be obtained to some extent by using the high-viscosity conductive paste 32, if the viscosity of the paste becomes too large, the viscoelastic behavior of the conductive paste 32 becomes unstable and paste stringing is performed. Occurs. Therefore, it has been difficult to produce a desirable conical conductive bump that is bilaterally symmetric and constant at a high height.
[0009]
Further, the conventional screen printing method shown in FIG. 6 has a problem that only one sheet can be printed in one reciprocation, resulting in poor work efficiency.
[0010]
[Problems to be solved by the invention]
It is an object of the present invention to provide a method and an apparatus for transferring a conductive paste having a high aspect ratio with a constant height to a substrate to be printed as much as possible. It is.
Another object of the present invention is to eliminate wasteful printing operations and further increase work efficiency.
[0011]
[Means for Solving the Problems]
In order to solve the above problems, the present invention increases the discharge amount of the conductive paste from the paste discharge hole of the printing plate by pressurization, and is fixed to an arc-shaped drum as a mechanism for fixing the substrate. By forming in such a manner, a gap is formed between the printing plate and the printing material, and a heat cutting means is interposed in this gap.
[0012]
Then, by driving the drum and the printing plate synchronously, more conductive paste is transferred, and heat fusion is performed at a higher position of the paste cylinder so as to form a conductive bump having a high aspect ratio. It is a thing.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a conductive bump forming method and a manufacturing apparatus thereof according to the present invention will be described with reference to FIG.
23 is, for example, a copper foil as a printed material having a length of 500 mm and a thickness of 0.018 mm. The copper foil 23 is fixed to the outer peripheral surface of the drum 13 while being supported by the clampers 11 at both ends. A large number of suction holes 16 are formed in the outer peripheral surface of the drum 13, and sucked by a suction pump 14 connected to the drum 13 to suck and fix the copper foil 23 to the outer periphery of the drum 13. Is done. The drum 13 is rotated in both forward and reverse directions at a constant speed by a driving device (not shown).
[0014]
A printing plate 31 is provided with its periphery supported by a fixed frame 15 so as to face the outer peripheral surface of the drum 13, and the printing plate 31 linearly moves in synchronization with the drum 13 by a driving device (not shown). It is configured. The printing plate 31 has, for example, a length of 1000 mm, a thickness of 0.5 mm, and about 100,000 paste discharge holes 30 of 0.2 mmΦ. The number and diameter of the paste discharge holes 30 are determined by the wiring pattern of the copper foil 23.
[0015]
Reference numeral 4 denotes a paste extrusion chamber provided on the upper surface of the printing plate 31. The paste extrusion chamber 4 is filled with a paste 32 having high viscosity and conductivity, and a pressure (not shown) is applied to the upper end via a pressure adjustment valve 3 for adjusting the discharge amount of the paste 32. A pressure source such as a pump is connected. A paste discharge port 18 for discharging the paste 32 is opened at the lower end portion of the paste extrusion chamber 4, and the outer periphery of the paste discharge port 18 faces the contact surface with the printing plate 31. A pressure seal 19 is provided for maintaining the interior at a high pressure.
[0016]
Before and after the paste extrusion chamber 4, pressing rollers 1 and 2 are provided, respectively. As shown in FIG. 1, the pressing roller 1 moves the printing plate 31 to the left, and the drum 13 Moves counterclockwise so that the printing plate 31 and the drum 13 are always in close contact with each other. Further, as shown in FIG. 2, the other pressing left roller 2 is configured so that the printing plate 31 and the drum 13 are always in close contact when the printing plate 31 moves rightward and the drum 13 rotates clockwise. Descend.
[0017]
Since the printing plate 31 is brought into close contact with the copper foil 23 of the drum 13 by the pressing roller 1 or 2, the printing plate 31 is bent in a reverse hemispherical shape. Thus, gaps 10 are formed respectively before and after the contact surface between the printing plate 31 and the drum 13. A heating light source 7 serving as a heating means is provided facing the gap 10. The light beam 8 emitted from the heating light source 7 in a direction perpendicular to the surface of the printing plate 31 has a wavelength that is easily absorbed by the paste 32, and is condensed by the lens 9 and is a part of the paste cylinder portion after transfer. The portion is locally heated and softened to stabilize the separation from the printing plate 31, and the shape of the conical top portion of the formed conductive bump 24 is sharpened.
As a result, the conductive bump 24 after transfer is formed with a high aspect ratio.
[0018]
Next, the operation of the embodiment of the present invention shown in FIG. 1 will be described.
First, the printing plate 31 having the paste discharge holes 30 of the target wiring pattern is fixed to the fixed frame 15. Further, a copper foil 23 having a predetermined length and thickness is supported by the clamper 11 on the drum 13 and sucked and set by the suction pump 14, and the conductive paste 32 is filled in the paste extrusion chamber 4.
[0019]
Next, the drum 13 is synchronized so that the peripheral speed of the drum 13 and the linear moving speed of the printing plate 31 coincide with each other, and is rotated and moved at a peripheral speed of 5 m / min, for example. The pressure in the paste extrusion chamber 4 is set to, for example, 0.5 MPa by the pressure adjustment valve 3. Further, one pressing roller 1 is lowered to bring the printing plate 31 and the copper foil 23 on the drum 13 into close contact.
[0020]
In this state, the conductive paste 32 is discharged and transferred onto the copper foil 23. For example, an infrared laser beam having a wavelength of 1.3 μm and an output of 10 W is emitted to the paste cylinder immediately after the transfer by the heating light source 7 provided in one gap 10 between the copper foil 23 and the printing plate 31 toward the paste side surface. Then, the light is condensed by the cylinder lens 9 and irradiated to the substantial center of the paste cylinder. Then, the surface temperature of the paste cylinder rises to about 50 degrees, the viscosity decreases locally, and the paste cylinder breaks into a conical shape from that portion.
[0021]
Hereinafter, when printing is continuously performed in the same procedure, the paste 32 pushed and transferred from the paste discharge hole 30 is broken one after another at a certain position as the printing plate 31 moves linearly and the drum 13 rotates. A conductive bump 24 is formed on the copper foil 23. Incidentally, the transfer amount of the conductive paste 32 to the copper foil 23 at this time was several times or more compared to the conventional case, and high-precision printing without variation was achieved.
[0022]
In FIG. 1, the operation is when the printing plate 31 moves from the right to the left in the drawing. In the present invention, however, printing is also performed when the printing plate 31 moves from the left to the right as shown in FIG. It is possible to print one sheet for each round trip.
That is, the other pressing roller 2 is lowered to bring the printing plate 31 and the copper foil 23 on the drum 13 into intimate contact, and the paste cylinder immediately after the transfer has a gap between the other of the copper foil 23 and the printing plate 31. Irradiation is performed toward the side of the paste by the heating light source 7 provided in 10. Other than that, the printing plate 31 moves linearly from left to right and the drum 13 rotates to the right.
[0023]
As described above, according to the present invention, the cylindrical paste 32 in the middle of transfer is stably cut at a fixed position, so that the conductive bumps 10 having high transfer accuracy and a large amount of transfer of the paste 32 are continuously formed. Generated. Further, the productivity is at least twice as high as that of the conventional printing method, and further, by adjusting the pressure in the chamber 4 and the output energy of the heating light source 7, it is not affected by the viscosity of the paste 32. Printing can be performed.
[0024]
In the above-described embodiment, the formation of the conductive bump 10 has been described. However, the present invention is not limited to this, and a high aspect ratio such as a plasma containment cell of a flat display panel, which requires a high printed matter is necessary. Also, it can be manufactured with high accuracy, and defects due to variations in height can be reduced.
[0025]
【The invention's effect】
According to the first aspect of the present invention, in the conductive bump manufacturing apparatus in which the conductive paste supplied to the paste discharge hole formed in the printing plate is transferred to the printing material, the printing material is placed on the outer peripheral surface. A drum that rotates while being fixed; a moving unit that moves the printing plate in a substantially linear manner in synchronization with rotation of the drum while being in local contact with the printing material; and the printing material on the printing plate From a paste extrusion chamber that is provided with a paste discharge opening facing a local contact position and extrudes the conductive paste filled inside by pressurization, and a local contact portion between the printing plate and the printing material As they leave, they move away from each other to form a gap between them, and a portion of the paste cylinder transferred from the printing plate to the substrate is locally heated in this gap. Since provided with a heating means that has the following effects.
(1) More conductive paste can be transferred to form conductive bumps with a high aspect ratio.
[0026]
(2) By rotating a rotating drum with a constant curvature at a predetermined speed, the separating speed can be controlled to a predetermined value, and the transfer amount of the conductive paste can be controlled to a predetermined amount.
[0027]
(3) The printed material can be separated with a certain curvature by simply attaching it to the drum, and the printed material can be prevented from being deformed by the transfer operation of the conductive paste, and the printed material can be attached to and removed from the drum. Becomes easier.
[0028]
(4) The transfer amount of the paste can be discharged as necessary and sufficient by pressurization, and a conductive bump having a high aspect ratio can be formed.
Incidentally, when the paste was extruded using a conventional squeegee, the transfer amount was 0.001 mm 3 per paste discharge hole.
On the other hand, according to a specific embodiment of the present invention, when the paste 32 is extruded at a drum peripheral speed of 5 m / min and a chamber internal pressure of 0.5 MPa, a paste discharge hole having a thickness of 0.5 mm and a hole diameter of 0.2 mm is obtained. The transfer amount was 0.006 mm 3 per piece.
From this, it can be seen that the transfer amount is increasing, and that the method of extruding the paste by air pressure or hydraulic pressure is effective.
[0029]
(5) When irradiation is performed on substantially the center of the paste cylinder, the surface temperature of the paste cylinder rises, the viscosity is locally reduced, and the paste cylinder breaks into an ideal conical shape from that portion. Further, it is possible to control so that the printing plate separation position is always constant, and even when a paste having a high viscosity is used, a conductive paste with little variation can be continuously generated without stringing.
[0030]
According to the invention of claim 2 Symbol placement, the heating means is absorbed by the paste firing the laser beam easily wavelength, so was allowed condensing the paste by the lens, efficiently many extremely small pieces of paste cylindrical cutting it can.
Incidentally, when the infrared laser light was not irradiated, the paste transfer amount variation was about 50%. However, when the infrared laser light was irradiated according to the present invention, the transfer amount variation was 5% or less, and the conductivity was small. It turns out that it is very effective for producing paste continuously.
[0031]
According to the invention of claim 3 Symbol placement, since the printing plate to face the side of the paste extrusion chamber provided with pressing rollers allowed to locally contact with the substrate, at a constant pressure printing plate to the substrate In addition to being able to be pressed, a larger gap can be formed between the printing plate and the printing material, and the heating and fusing treatment of the formed conductive bumps becomes easier.
[0032]
According to the invention of claim 4 Symbol mounting, in synchronization with the drum and the printing plate to each other is provided to be forward and reverse movement, when one direction of movement of the to face one side of paste extrusion chamber drum and the printing plate One pressing roller is provided to bring the printing plate into local contact with the printing material, and the printing plate is locally applied to the printing material when moving in the other direction of the drum and the printing plate facing the other side of the paste extrusion chamber. Since the other pressing roller that is brought into contact with each other is provided, not only printing can be performed when the printing plate 31 moves in one direction, but printing can also be performed when the printing plate 31 moves in the other direction. Can print one sheet at a time, greatly improving work efficiency.
[0033]
According to the invention of claim 5 Symbol mounting, the drum rotates while sucking fix the copper foil on the outer circumferential surface, a printing plate substantially linearly in synchronism with the rotation of the copper foil and locally contact with the drum moving The conductive paste that is fixedly provided with the paste discharge port facing the local contact position between the moving means and the copper foil in the printing plate is pushed out by the air pressure adjusted by the pressure regulating valve. It has a paste extrusion chamber, and moves away from the local contact between the printing plate and the copper foil to move away from each other to form a gap between them, and transfer from the printing plate to the copper foil in this gap In order to locally heat the paste cylinder part, a laser beam of a wavelength that is easily absorbed by the paste is provided, and a heating means for condensing the paste on a part of the paste by a lens is provided. It is effective in forming a conductive bump on a copper foil used in the manufacture of the plate.
[Brief description of the drawings]
FIG. 1 is an operation explanatory view showing an embodiment of a conductive bump forming method and a manufacturing apparatus therefor according to the present invention, and is a printing explanatory view when moving in one direction (at the time of forward movement).
FIG. 2 is a printing explanatory view when moving in the other direction (at the time of backward movement) in the operation explanatory view of the conductive bump forming method and the manufacturing apparatus thereof in FIG. 1;
FIG. 3 is an exploded cross-sectional view before lamination in the method for manufacturing a multilayer wiring board.
4 is a cross-sectional view after laminating the members shown in FIG. 3;
FIG. 5 is a cross-sectional view after completion of the multilayer wiring board.
FIG. 6 is an operation explanatory view of a conventional conductive bump forming method and a manufacturing apparatus thereof.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... One pressing roller, 2 ... The other pressing roller, 3 ... Pressure adjusting valve, 4 ... Paste extrusion chamber, 7 ... Heating light source as heating means, 8 ... Light source, 9 ... Cylinder lens, 10 ... Gap DESCRIPTION OF SYMBOLS 11 ... Clamper, 13 ... Drum, 14 ... Suction pump, 15 ... Support frame, 16 ... Adsorption hole, 18 ... Paste discharge port, 19 ... Pressure seal, 20 ... Insulating core substrate, 21 ... Wiring pattern, 22 ... Insulation Prepreg, 23 ... copper foil as substrate, 24 ... conductive bump, 25 ... wiring pattern, 28 ... multilayer wiring board, 30 ... paste discharge hole, 31 ... printing plate, 32 ... conductive paste, 33 ... squeegee, 34 ... Table.

Claims (5)

In a conductive bump manufacturing apparatus in which a conductive paste supplied to a paste discharge hole formed in a printing plate is transferred to a printing material, a drum that rotates while fixing the printing material on an outer peripheral surface, A moving means for moving the printing plate in a substantially linear manner in synchronization with the rotation of the drum while being in local contact with the printed material, and a paste spout near the local contact position of the printing material on the printing plate. Move away from the paste extrusion chamber, which is provided facing the outlet and extrudes the conductive paste filled inside by pressurization, and the local contact part between the printing plate and the substrate, and moves away from each other. a gap is formed between them, in the gap, formed by and a heating means for locally heating a portion of the paste cylindrical section has been transferred from the printing plate to the substrate Apparatus for producing a conductive bump, wherein the door. Heating means, a laser beam tends wavelength is absorbed in the paste firing, lens manufacturing apparatus of the conductive bump of claim 1 Symbol mounting, characterized by comprising brought condensing the paste by. Apparatus for producing a conductive bump of claim 1 Symbol mounting, characterized in that the paste extrusion chamber printing plate to face the side of formed by providing a pressing roller allowed to locally contact with the substrate. The drum and the printing plate are provided so that they can move forward and backward in synchronization with each other, facing the one side of the paste extrusion chamber, and the printing plate is locally pressed against the substrate when moving the drum and the printing plate in one direction. In addition to providing one pressing roller, the other pressing roller is provided to face the other side of the paste extrusion chamber and to locally press the printing plate against the substrate when moving the drum and the printing plate in the other direction. It is Te apparatus for manufacturing conductive bump of claim 1 Symbol mounting characterized. In a conductive bump manufacturing apparatus in which a conductive bump supplied to a paste discharge hole formed in a printing plate is transferred to a copper foil for a multilayer wiring board to form a conductive bump. A drum that rotates while being suction-fixed to a surface, a moving means that moves the printing plate substantially linearly in synchronism with rotation of the drum while being in local contact with the copper foil, and the copper in the printing plate A paste extrusion chamber that is fixedly provided with a paste discharge port facing a local contact position with the foil, and that extrudes the conductive paste filled therein with air pressure adjusted by a pressure regulating valve; As the distance from the local contact portion between the printing plate and the copper foil is increased, the printing plate and the copper foil are moved away from each other to form a gap therebetween, and the page transferred from the printing plate to the copper foil in the gap is formed. Manufacturing of conductive bumps characterized by providing a heating means that emits a laser beam having a wavelength that is easily absorbed by a paste for locally heating a cylindrical portion and focuses the light on a part of the paste by a lens apparatus.

Images