JPH04354176A - Manufacture of high-density wiring board - Google Patents

Abstract

PURPOSE:To provide a high-density wiring board manufacturing method which can lay conductors on a high-density wiring board having triple and quadruple intersections in a less number of processes and at a high speed and, at the same time, can stably stick the conductors to the wiring board. CONSTITUTION:An adhesive layer 11 at a section where a conductor 12 is buried in the layer 11 is activated (thermally softened) by irradiating the part with a laser beam 20 from a YAG laser oscillator 21 from two lateral directions through optical fibers 23 and, at the same time, the frictional force between the conductor 12 and a stylus 30 to be used for burying the conduct 12 in the layer 11 is relieved by applying vibrations of an audible frequency to the stylus 32.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a high-density wiring board in which insulated conductors having a desired circuit pattern are attached to a support substrate.

0002

[Prior art] Usually, an insulated conductor (hereinafter referred to as a conductor)
The wiring board to which the wiring board is attached is manufactured by wiring and fixing conductive wires through an adhesive layer on a support substrate.

[0003] High-density wiring boards requiring multilayer circuits are manufactured by bonding a plurality of adhesive layers in which conducting wires are wired and fixed.

A conventional method for manufacturing such a high-density wiring board is disclosed in US Pat. No. 3,674,914. In this method, a cured thermosetting resin adhesive layer is coated on a laminated sheet, and then ultrasonic energy is used to heat and soften the adhesive layer, and conductive wires are sequentially pushed into the area, and then the adhesive layer is applied. This method involves heating and curing and permanently embedding the conductive wire.

Furthermore, Japanese Patent Laid-Open No. 62-84587 discloses a method of activating an adhesion layer using laser energy and attaching a conductive wire to the activated portion, in which the laser energy and laser beam pulse frequency are controlled by the conductor. The technical content of controlling the installation speed to a constant value is disclosed.

Furthermore, Japanese Patent Application Laid-Open No. 57-136391 discloses that in a method of embedding a laying conductor in an adhesive layer, in addition to ultrasonic energy, in order to soften the adhesive layer, ultrasonic energy is applied from the front for the purpose of assisting the ultrasonic energy. The content of irradiating with a CO 2 laser beam is disclosed.

Japanese Patent Publication No. 1-33958 discloses that a photocurable adhesion layer is formed on a support substrate, and while conducting wires are embedded and laid on the layer, light is irradiated to the part where the laying has been completed. A method is shown in which the entire surface of the adhesive layer is irradiated with light after the installation is completed to harden the entire area.

[0008]

Problems to be Solved by the Invention The following problems have been pointed out in the conventional method for manufacturing high-density wiring boards described above.

First, the method shown in US Pat. No. 3,674,914 uses ultrasonic energy to thermally activate the adhesion layer, and then applies pressure energy to the stylus to press the conductive wire. are doing.

[0010] Therefore, in order to increase the wiring speed, it is necessary to increase both the ultrasonic energy and the pressurizing energy, and at the point where the conductors intersect, there is a strong hammering and friction force from the stylus. , the conductor may be deformed or stretched and broken.

[0011] Therefore, the wiring speed is set to 3.8 m/
Furthermore, in high-density wiring structures such as triple or quadruple intersections, disconnections may occur even at low wiring speeds, so
After wiring up to the intersection point and embedding the existing wiring by press molding, the remaining wiring must be continued again, which is a very troublesome work.

[0012] Furthermore, in JP-A-62-84587 and JP-A-57-136391, for example,
As shown in FIG. 4, the irradiation angle 2 of the laser beam 1 from the front is preferably set to 90 degrees because the irradiation of the laser beam is obstructed by the conductive wire 3 that has already been wired, but in practice it is Since the feed roller 4 and the conductive wire guide 5 are located in front of the stylus 6, the irradiation angle 2 cannot be set large.

Furthermore, since a CO 2 laser is used, the laser beam is transmitted by reflection from a plurality of mirrors 7, so the irradiation position may shift due to vibrations such as rotation of the wiring head, or the mirror may It is necessary to always maintain the irradiation angle at an appropriate angle, which has the disadvantage that adjustment work is time-consuming.

[0014] Furthermore, in Japanese Patent Publication No. 1-33958,
The amount of ultraviolet energy required to harden the adhesion layer changes depending on the acceleration/deceleration range when the conductor is laid, resulting in quality defects such as variations in the amount of conductor embedded.
Since this is a method of wiring conductors while curing the adhesive layer, the adhesive layer at the points where the wiring has already been hardened is hardened at the triple and quadruple intersections required for high-density wiring, and the There was a problem that the fixation could not be carried out smoothly.

The present invention was made in view of the above circumstances, and an object of the present invention is to enable high-speed wiring in a high-density wiring board having triple and quadruple intersections. It is an object of the present invention to provide a method for manufacturing a high-density wiring board, which has no deformation or disconnection of conducting wires, and guarantees stable wiring work.

[0016]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a high-density wiring in which an adhesive layer of heat-activated resin is formed on a support substrate, and an insulated conductor wire is attached on the adhesive layer. In the method for manufacturing the board, a YAG laser beam is irradiated laterally to the tip of the wiring head to heat the surface of the adhesive layer and the lower part of the insulated conductor, and the insulated conductor is pressed and fixed onto the adhesive layer. It is characterized by vibrating the stylus at an audio frequency.

[0017]

[Operation] As is clear from the above structure, activation (thermal softening) of the adhesion layer is performed by irradiation with a YAG laser beam, and the conducting wire is not struck by ultrasonic waves. Also,
The conductor is embedded using only the static pressure of the stylus.

On the other hand, since the vibration applied to the stylus is used to reduce the frictional force between the stylus and the conducting wire pressurized by the stylus, a low frequency is used. Therefore, no breakage due to damage or stretching of the conducting wire due to high-energy ultrasonic vibration as in the prior art is observed.

Furthermore, irradiation of the laser beam from the lateral direction enables fixing at multiple intersections without being obstructed by the conductor wires already laid in the front.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a high-density wiring board according to the present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a side view showing the structure of a high-density wiring board wiring apparatus used in the method of the present invention, and FIG. 2 is a plan view of the apparatus.

The configuration of this device will be explained based on FIGS. 1 and 2. As a mechanism for activating (thermally softening) the adhesion layer 11 of heat-activated resin or the like formed on the support substrate 10, The laser beam 20 is applied under optimal conditions (frequency: 10 to 40 KHz,
A YAG laser oscillator 21 generates an output of 20 to 40 W, which is branched into two by a branching unit 22, and connected to an output lens 24 by an optical fiber 23 with a core diameter of 0.3 mm.
will be transmitted up to.

The light is focused by the output lens 24 and irradiated onto the interface between the conducting wire 12 and the adhesive layer 11 from two locations in the lateral direction.

Note that the conducting wire 12 is fed by a feed roller 13 and a conducting wire guide 14.

At this time, in the side direction irradiation angle α, 30
~60°, and the lateral illumination angle β shown in Fig. 2 is 0.
The angle is set between 45° and strong fixation is possible even at multiple intersections.

On the other hand, the stylus 30 for embedding the conductive wire 12 in the adhesive layer 11 is provided with a vibration generator 31.
The stylus 30 is vibrated at an audible frequency of 1 to 5 KHZ to reduce the frictional force between the conductive wire 12 and the stylus 30. The vibration at this time is given by a piezoelectric element, etc.
The energy is set to an extent that does not damage the conducting wire 12.

Furthermore, the pressure device 32 attached to the stylus 30 uses an electromagnetic actuator to press the stylus 30.
0 into the adhesive layer 11. The appropriate pressing force at this time is 60 to 80 g/cm 2 .

As a result of wiring with the apparatus configured as above,
The rate of increase in resistance due to damage, deformation, and stretching of the conductor is 3 even in high-speed wiring processing at a wiring speed of 12 m/min.
~3.5%, which is lower than the conventional low speed (3.8 m/min), and also ensures that no wire breakage occurs at the 100 intersections where the conductor wires 12 intersect triple and quadruple. It could be confirmed.

Furthermore, in the embodiment of the present invention, wiring was conducted with and without applying vibrations at an audible frequency to the stylus 30, and the rate of increase in resistance of the conductive wire 12 was compared.

As a result, the resistance increase rate of the conductor 12 was 3 to 3.5% when vibration was applied, and 9 to 3.5% when vibration was not applied.
10% (wiring speed of both 12 m/min). Therefore, by adding vibration to the stylus 30, the frictional force between the stylus 30 and the conductive wire 12 is alleviated, and the stretching of the conductive wire 12 by the stylus 30 is reduced. , it can be understood that deformation can be kept small.

Furthermore, using a CO 2 laser and a YAG laser, a laser beam was irradiated onto the conductive wire on the adhesion layer using the method shown in FIG. 3, and the adhesion strength and deterioration after adhesion were compared. The force was 25 g, and the adhesion force by the CO 2 laser was 10 g, and it was found that stronger adhesion force could be obtained by using the YAG laser.

Furthermore, regarding the quality after adhesion, YAG
When a laser is used, the performance remains unchanged from before the adhesion, but in the case of CO2, the absorption rate of the adhesion layer and the insulation layer of the conductor is high, so evaporative gas is generated when the adhesion is made, which causes soot. (Carbide) tends to adhere black to the adhesion area and deteriorate quality. (Note) Experimental conditions 1. Laser beam scanning speed 12m/m
in2. laser power
30W Next, an example of the present invention and a comparative example will be compared. [Comparative Example 1] Conventional method of softening and activating the adhesive layer using ultrasonic energy alone (using PCKT's wiring machine T-2000, ultrasonic output 38 W, wiring speed 3.8 m/min)
As a result of wiring, the resistance increase rate of the conducting wire was as high as 11%, and the number of wire breaks at intersections was 2/100 at triple intersections and 35/100 at quadruple intersections. [Comparative Example 2] As a result of wiring using a method that uses laser energy as ultrasonic energy (laser output 30 W, ultrasonic output 20 W, wiring speed 3.8 m/min), the resistance change rate of the conductor wire was 7 to 7. 8%, higher than the example of the present invention,
Furthermore, disconnections at intersections occurred at 0/100 locations at triple intersections, but at 5/100 locations at quadruple intersections.

[0033] Since this method uses high-frequency ultrasonic energy to soften and activate the adhesion layer, the strong hammering and frictional force applied to the conductor from the stylus are not removed; The resistance change rate is high, and wire breakage occurs at the quadruple intersection.

A summary of the Examples and Comparative Examples described above is shown in Attached Table 1.

[0035]

[Table 1]

[0036]

As explained above, the method for manufacturing a high-density wiring board according to the present invention has the following special effects. (1) According to the method of the present invention, the heating by the laser beam and the effect of reducing frictional force by vibration make it possible to attach conductors at a speed more than three times faster than conventional methods, and
The wiring time required for a wiring pattern with 20,000 intersections on a mm board was reduced from the conventional 300 minutes to 80 minutes. Therefore, it has the effect that the wiring time on a high-density wiring board can be significantly shortened. (2) According to the method of the present invention, it is possible to suppress damage and deformation of the wires that have been wired during wiring work that is faster than in the past, and there is no disconnection of the wires at triple or quadruple intersections. This has the effect of significantly improving the quality of high-density wiring boards. (3) According to the method of the present invention, the wiring work is interrupted until the double intersection as in the conventional method, the existing wiring is embedded by press molding, and then the wiring is continued until the triple or quadruple intersection. There is no need for the troublesome process of
It is possible to wire up to multiple intersections, simplifying the pressing process,
This has the effect of significantly improving work efficiency, such as shortening the setup time for the wiring machine. (4) According to the method of the present invention, by irradiating the tip of the wiring head with a laser beam from two positions in the lateral direction, there is no possibility that the laser beam will be obstructed by the already laid conductor wires at the triple and quadruple intersections required for high-density wiring. This allows for good adhesion of the conductor. (5) According to the method of the present invention, by using an optical fiber as the transmission path of the laser beam, there is an effect that fluctuations in the laser irradiation position, laser irradiation spot diameter, etc. are eliminated, and stable conductor wiring is possible. .

[Brief explanation of drawings]

FIG. 1 is a side view showing the configuration of a high-density wiring board wiring apparatus used in the method of the present invention.

FIG. 2 is a plan view of the device shown in FIG. 1.

FIG. 3 is a side view showing a wiring experiment method using a CO 2 laser and a YAG laser.

FIG. 4 is a side view showing the configuration of a conventional wiring board wiring device.

[Explanation of symbols]

10 Support board 11 Adhesion layer 12 Conductor wire 21 YAG laser oscillator 22 Branch unit 23 Optical fiber 24 Laser emission lens 30 Stylus 31 Vibration generator 32 Pressure device

Claims (2)

[Claims] 1. A method for manufacturing a high-density wiring board in which an adhesive layer of heat-activated resin is formed on a support substrate and an insulated conductor is attached on the adhesive layer, in which a YAG laser beam is applied to the tip of a wiring head. A high-temperature heating system characterized by irradiating from the side to heat the surface of the adhesive layer and the lower part of the insulated conductor, and vibrating the stylus at an audio frequency for pressurizing and fixing the insulated conductor on the adhesive layer. A method for manufacturing a density wiring board. 2. The method of manufacturing a high-density wiring board according to claim 1, wherein an optical fiber is used as a transmission path for the YAG laser beam.