JPH10209689A - Manufacture of circuit module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently connect components to a board with irradiation of a laser beam on connecting parts by using a harmonic laser beam for irradiating them. SOLUTION: A second harmonic laser beam LB having a lower reflectivity to a metal of board electrodes 3a than that of the fundamental beam is applied to heat the board electrodes 3a by its irradiation energy, the heat of the electrodes 3a conducts to bumps 2 to melt them, the molten bumps 2 are hardened to electrically connect the electrodes 1a of the components 1 to the electrodes 3 of the board 3. This reduces the reflection loss, raises the absorption ratio to give required energy for connecting the components in a short irradiation time to the bumps 2, thus efficiently connecting the components by the laser beam irradiation in a short time.

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 circuit module for connecting an electronic component to a substrate by using irradiation energy of a laser beam.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional method for connecting components of this type, wherein 1 is an electronic component such as an IC or LSI, 1a is an electrode provided on the lower surface of the electronic component 1, and 2 is a component electrode. 1a
(Projection electrodes), 3 is a laser light transmitting substrate, 3a is an electrode (land) provided on the upper surface of the substrate 3, 4 is a lens, and L is a laser beam.

The bump 2 is made of a metal material having a lower melting point than each of the electrodes 1a and 3a, for example, an Sn-Pb alloy (solder), and itself serves as a bonding material.

In order to electrically connect the electronic component 1 to the substrate 3, first, the electronic component 1 is positioned using an unillustrated component suction tool such that the component electrode 1 a of the electronic component 1 matches the substrate electrode 3 a. After being aligned, it is placed on the substrate 3.

[0005] In this component mounting state, a laser beam L is applied from the lower surface side of the substrate 3 through the substrate 3 to the substrate electrode 3a.
Irradiation. As a result, the substrate electrode 3a is heated by the irradiation energy of the laser beam L, the bump 2 is heated and melted by heat conduction from the substrate electrode 3a, and the electrode 1a of the electronic component 1 and the substrate 3 Electrode 3a is electrically connected.

[0006]

The laser light L is an infrared light (basic wave light) of a continuous pulse train at a wavelength of 1064 nm using a CW oscillation Q-switched YAG laser using an Nd: YAG single crystal as an oscillation source. ) Is commonly used. However, since the fundamental wave light of the YAG laser has a high reflectance with respect to a metal substance, it is inevitable to apply a predetermined energy to a connected part such as a bump by irradiating the laser light in order to compensate for the reflection loss. And the time required for component connection increases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a circuit module capable of efficiently connecting components by irradiating a laser beam.

[0008]

In order to achieve the above object, the present invention relates to a method for manufacturing a circuit module for connecting an electronic component and a substrate by irradiating a laser beam to a portion to be connected. The use of harmonic light is its main feature.

According to the present invention, by using a harmonic light having a low reflection loss and a high absorptance as the irradiation laser light, a desired light can be applied to the heated portion in a shorter irradiation time than in the case where the fundamental light is irradiated to the connected portion. Energy can be given.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] FIG. 1 relates to a first embodiment of the present invention, in which 1 denotes an electronic component such as an IC or LSI, 1a denotes an electrode provided on the lower surface of the electronic component 1, and 2 denotes a component. Bumps (protrusion electrodes) provided on the electrodes 1a, 3 is a substrate, 3a is an electrode (land) provided on the upper surface of the substrate 3, 4 is a lens, 5
Is a laser oscillator, 6 is a harmonic generator, 7 is an optical splitter,
Reference numeral 8 denotes an optical fiber, and LB denotes second harmonic light.

The substrate 3 is made of ceramics or glass such as sapphire, zirconia, calcium fluoride, aluminum nitride, alumina, and quartz, or resin such as polyimide, acrylic, PET, silicon, epoxy, and glass epoxy.
It has transparency to the laser beam LB.

The component electrode 1a and the substrate electrode 3a are made of gold, silver, aluminum, copper, nickel, platinum, palladium or an alloy thereof. The bump 2 is made of a metal material having a lower melting point than the electrodes 1a and 3a, for example, an Sn-Pb alloy (solder).
Etc., which themselves serve as a bonding material.

The laser oscillator 5 comprises a CW oscillation Q-switched YAG laser using a Nd: YAG single crystal,
Infrared light (fundamental wave light) of a continuous pulse train at a wavelength of 1064 nm
Is emitted.

The harmonic generator 6 includes a nonlinear optical crystal element such as KDP and ADP, a filter or a prism for separating harmonics, etc., and outputs the fundamental wave light (wavelength 1064 nm, infrared light) emitted from the laser oscillator 5. The light is converted into green light (second harmonic light) having a wavelength of 532 nm.

The optical splitter 7 splits the second harmonic light converted by the harmonic generator 6 into a predetermined number, here a number corresponding to the number of electrodes of the electronic component 1.

The optical fiber 8 is of a silica type, and guides the second harmonic light LB split by the optical splitter 7 to each lens 4.

The lens 4 is disposed on the lower side of the substrate 3 so as to correspond to the electrode position of the electronic component 1 mounted on the substrate 3, and the second harmonic light guided through the optical fiber 8. The LB is condensed on the substrate electrode 3a via the substrate 3.

That is, in the example shown in the drawing, an optical system that can simultaneously irradiate a plurality of second harmonic lights LB corresponding to the number of electrodes of the electronic component 1 from the lower side of the substrate 3 toward the substrate electrode 3a corresponding to the component. The system is set up.

In order to electrically connect the electronic component 1 and the substrate 3, first, the electronic component 1 is aligned using a component suction tool (not shown) so that the component electrode 1a and the substrate electrode 3a coincide. And then placed on the substrate 3.

Then, in this component mounted state, the substrate electrode 3a is irradiated with the second harmonic light LB from the lower surface side of the substrate 3 via the substrate 3. As a result, the substrate electrode 3a is heated by the irradiation energy of the second harmonic light LB, and the bump 2 is heated and melted by heat conduction from the substrate electrode 3a. The electrode 3a of the substrate 3 is electrically connected. Incidentally, the power and irradiation time of the second harmonic light LB applied to each substrate electrode 3a are determined by a preliminary connection experiment.

According to the present embodiment, since the second harmonic light LB having a lower reflectivity to the metal material such as the substrate electrode 3a than the fundamental light is used as the irradiation laser light, the substrate light is applied to the substrate electrode 3a. As compared with the case, the reflection loss is reduced and the absorptance is increased, the energy required for component connection is applied to the bump 2 in a short irradiation time, and the component connection by laser beam irradiation can be efficiently performed in a short time.

In the above embodiment, the bump is used as a bonding material. However, a bonding material layer having a lower melting point than the bump, for example, a solder layer is provided on the bump surface, and only the bonding material layer is used. The same components may be connected by heating and melting. The same action and effect can be obtained even when the bumps are eliminated and a bonding material such as solder is provided on one of the component electrode and the substrate electrode, and the component electrode and the substrate electrode are connected using the bonding material. Can be expected.

In the above-described embodiment, an IC, an LSI, or the like is exemplified as the electronic component. However, the connection method described in this embodiment may be applied to a chip-like electronic component such as a chip capacitor, a chip inductor, a chip resistor, or the like. Widely applicable to electronic components.

Further, the fundamental wave light of the YAG laser is
In the above-described example, the light is converted into higher harmonic light and radiated, but the fundamental light is converted into third harmonic light (wavelength 355 nm, blue light) or fourth harmonic light (wavelength 266 nm, ultraviolet light) and then irradiated. Even in this case, similar component connection can be performed.

In addition, an example of irradiating harmonic light of YAG laser light has been described, but a CW oscillating CO ₂ laser is used as an oscillation source, and its fundamental wave light (wavelength 10.6) is used.
The same operation and effect can be obtained by irradiating harmonic light obtained by converting (μm, far-infrared light).

Furthermore, the above-described embodiment irradiates a connected portion such as a substrate electrode or a bump with harmonic light through the substrate. However, the connected portion is directly irradiated with the harmonic light to give energy. Is also good.

Furthermore, the method of connecting parts by heating and melting the bumps or the bonding material has been exemplified. However, the connection method described in the above embodiment is applicable to the case where the parts are connected by thermocompression bonding without using a bonding material. Is also effective.Specifically, if the bumps or the electrodes are heated to a temperature lower than the melting point by irradiation energy while applying a predetermined pressure to the electronic component mounted on the substrate, the same procedure is used. The components can be connected by thermocompression bonding.

[Second Embodiment] FIG. 2 relates to a second embodiment of the present invention, in which 11 is an electronic component having lower heat resistance than the electronic component 1, and 11a is provided on the lower surface of the electronic component 11. Reference numeral 12 denotes a bump (projection electrode) provided on the component electrode 11a, LB1 denotes a fundamental light, and LB2 denotes a second harmonic light. The other configuration is the same as that of the first embodiment, and the description thereof will be omitted using the same reference numerals.

The present embodiment differs from the first embodiment in that fundamental light and second harmonic light are selectively used in accordance with the type of electronic component connected on the substrate 3. For example, when two kinds of electronic components 1 and 11 having different heat resistances are connected to the substrate 3, the fundamental wave light LB <b> 1 of the YAG laser light is applied to the low heat resistance electronic components 11 in order to avoid a rapid temperature rise. Used, while the first heat-resistant electronic component 1
As in the embodiment, the second fundamental wave light LB of the YAG laser light
2 is used to make the connection.

In the example shown, each of the electronic components 1, 1
The fundamental wave light LB1 and the second
Although it is shown that the harmonic light LB2 can be simultaneously irradiated from the lower side of the substrate 3, the electronic components 1 and 2 can be selectively irradiated with the fundamental light and the second harmonic light by using an optical system.
The irradiation may be performed by appropriately switching the fundamental wave light and the second harmonic light every 11.

According to the present embodiment, by using the fundamental light LB1 and the second harmonic light LB2 selectively according to the type of electronic component connected on the substrate 3, thermal damage to the electronic component at the time of component connection is reduced. As a result, it is possible to prevent quality deterioration due to the damage. Second harmonic light LB2
The operation and effect of using are the same as in the first embodiment.

In the above embodiment, an example in which the fundamental wave light and the second harmonic light of the YAG laser are selectively used has been described. However, the harmonic light other than the second harmonic light and the fundamental light may be selectively used. Alternatively, the second to fourth harmonic light may be selectively used without using the fundamental light.

Also, an example in which the fundamental wave light and the harmonic wave light of the YAG laser light are selectively used has been described.
Similar functions and effects can be obtained by using an O ₂ laser as an oscillation source and selectively using its fundamental light and harmonic light.

[0034]

As described in detail above, according to the present invention,
By using the harmonic light as the irradiation laser light, the reflection loss is reduced and the absorptance is increased compared to the case where the fundamental wave light is irradiated to the connected part, and the energy required for component connection to the connected part in a short irradiation time It is possible to efficiently connect components by laser beam irradiation in a short time.

[Brief description of the drawings]

FIG. 1 is a diagram showing a component connection method according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a component connection method according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a conventional component connection method.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electronic component, 1a ... Component electrode, 2 ... Bump, 3 ... Substrate, 3a ... Substrate electrode, 4 ... Lens, 5 ... Laser oscillator, 6 ... Harmonic generator, 7 ... Optical splitter, 8 ... Optical fiber, LB: second harmonic light, 11: electronic component, 11a: component electrode, 12: bump, LB1: fundamental wave light, LB2: second harmonic light.

Continued on the front page (72) Inventor Tomonori Fujii 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denki Co., Ltd. (72) Mitsuo Ueno 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denki Stock Within the company (72) Inventor Iwao Fujikawa 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denki Co., Ltd. (72) Inventor Kazuyuki Shibuya 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denki Co., Ltd. Inside

Claims (5)

[Claims] 1. A method of manufacturing a circuit module for irradiating a connected portion with a laser beam to connect an electronic component and a substrate, wherein a harmonic light is used as an irradiating laser beam. . 2. The method for manufacturing a circuit module according to claim 1, wherein fundamental wave light is used in combination as irradiation laser light, and harmonic light and fundamental wave light are selectively used for connecting components to a substrate. 3. The method for manufacturing a circuit module according to claim 1, wherein the oscillation source of the irradiation laser light is a YAG laser. 4. The oscillation source of the irradiation laser light is a CO ₂ laser. The method for manufacturing a circuit module according to claim 1, wherein: 5. The method for manufacturing a circuit module according to claim 1, wherein the fundamental wave light is converted into higher harmonic light using a nonlinear optical crystal element.