JPH04280990A - Local plating device - Google Patents

Abstract

PURPOSE:To form a bump for connecting the inner lead of TAB and a semiconductor chip with high quality and precision. CONSTITUTION:A mask 21 is arranged on the rear of a material 2 to be plated, an opening 21a is provided to the mask 21 to reflect an irradiating laser beam 6 with its inner periphery and to transmit the beam to the rear of the material 2, and the variance in the laser beam output reaching the rear of the material 2 is reduced by the reflection in the opening 21a.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The inventions according to claims 1 and 2 are, for example, TAB (Tape Automated B).
The present invention relates to a local plating device for plating and forming contacts and electrodes on parts of electronic device parts, such as bumps for connecting inner leads (onding) and semiconductor chips.

0002

2. Description of the Related Art FIG. 5 is a sectional view showing a conventional local plating method for electrical terminals, which is disclosed in, for example, Japanese Patent Publication No. 60-45278. In the figure, a material to be plated 2 such as an electrical terminal is provided on a cathode 1 . A mask 3 is provided around the material 2 to be plated. Further, a nozzle 5 that forms a jet stream 4a of plating solution is provided facing the material to be plated 2.

In such a conventional jet-type local plating method, a voltage is applied between the cathode 1 and an anode (not shown) to blow out a jet 4a of plating solution onto the area to be plated. This method makes it possible to perform local plating at high speed without masking each material 2 to be plated.

Next, FIG. 4 shows, for example,
FIG. 2 is a configuration diagram showing a conventional local plating method using a laser, which is disclosed in the above publication. In the figure, a plating solution 4 is filled in a container 7 made of a material that transmits a laser beam 6, such as quartz. In the plating solution 4, a glass plated material 8 serving as a cathode and an anode 9 are placed facing each other. A metal layer 10 is formed on the surface of the material to be plated 8 . The material to be plated 8 and the anode 9 are powered by a power source 11.
and the voltage modulator 12. An energy source 13 such as a laser oscillator, a laser modulator 14, a lens 15, and a scanning mirror 16 are provided outside the container 7.

The laser 6 oscillated by the energy source 13 and passed through the laser modulator 14 is focused by a lens 15, then positioned by a scanning mirror 16, and transmitted through a container 7 to be irradiated onto a material 8 to be plated. The irradiated laser 6 also passes through the glass plated material 8, and the metal layer 1
Focus is established at 0. Further, the material to be plated 8 is set to a negative potential by the power source 11, and thereby electroplating is performed. At this time, the metal layer 10 of the material to be plated 8 becomes locally hot due to the irradiation with the laser 6, so that the plating speed increases. In addition, without masking the material 8 to be plated, μm
It is possible to perform fine local plating on the order of .

[0006]

[Problem to be solved by the invention] In the conventional jet plating method that does not use a laser as described above, the plating film tends to be granular, and cracks occur at the interface between the plating film and the material to be plated 2. There were some problems, such as: In addition, in the conventional jet plating method using a laser, the position of the plating part is specified by the scanning mirror 16, so the scanning position accuracy is poor, and the focus of the laser 6 may shift, or the incident angle of the laser 6 with respect to the metal layer 10 may change. As a result, the power density of the laser 6 irradiated to the metal layer 10 and the laser absorption rate of the metal layer 10 change, resulting in variations in plating quality.

The inventions according to claims 1 and 2 have been made with the aim of solving the above-mentioned problems, and are aimed at stabilizing the laser output that reaches the back side of the material to be plated and achieving high-speed processing. The purpose of the present invention is to obtain a local plating device that can suppress variations in plating quality while maintaining the plating speed.

[0008]

[Means for Solving the Problems] The local plating apparatus of the invention according to claim 1 is characterized in that a mask is placed on the back surface of the material to be plated, and the irradiated laser beam is transmitted while being reflected on the inner peripheral surface to coat the material. The mask has an opening that allows access to the back side of the plating material. In the local plating apparatus of the invention according to claim 2, a laser transmitting member is arranged on the back surface of the material to be plated, a mask is arranged on the surface of the laser transmitting member opposite to the material to be plated, and the irradiated laser The mask is provided with an opening through which the laser beam is transmitted while being reflected on the inner circumferential surface and reaches the laser transmitting member.

[0009]

In the invention according to claim 1, by transmitting the laser while being reflected within the opening of the mask, variations in the laser output reaching the back surface of the material to be plated are suppressed. In the invention according to claim 2, by transmitting the laser while being reflected within the opening of the mask, variations in the laser output reaching the back surface of the material to be plated are suppressed, and the laser beam is transmitted to the back surface of the material to be plated through the laser transmitting member. By letting the laser reach the target, the output of the laser is efficiently applied to the material to be plated.

0010

Embodiments Hereinafter, embodiments of the invention according to claim 1 will be described with reference to the drawings. FIG. 1 shows an embodiment of the invention according to claim 1 (
7 is a configuration diagram showing a local plating apparatus according to the first embodiment, in which the same or equivalent parts as in FIG. 6 are denoted by the same reference numerals, and the explanation thereof will be omitted. In the figure, the material to be plated 2 is made of copper, phosphor bronze, or the like. A mask 2 made of metal such as stainless steel or molybdenum is placed on the back side of the material to be plated 2.
1 is in contact. This mask 21 is powered by a power source (not shown).
It is connected to the cathode. The mask 21 has an opening 21
A is provided. The inner circumferential surface of the opening 21 is polished to be smooth in order to easily reflect the laser 6, and the diameter on the incident side of the laser 6 is larger than the diameter on the output side (the side of the material to be plated 2). There is. The lens 15 has an opening 21a
is placed opposite. On the surface of the material to be plated 2,
Nozzles 5 that form a jet stream 4a of plating solution 4 face each other.

In the local plating apparatus configured as described above, the mask 21 is arranged so that the current flows through the jet stream 4a.
A voltage is applied between the nozzle 5 and an anode (not shown), and the plating solution 4 is injected from the tip of the nozzle 5 onto the plating portion of the material to be plated 2. The laser 6 is focused by the lens 15 so that most of its energy enters the opening 21a, that is, the beam diameter is smaller than the opening 21a, and the laser 6 is focused at the same time as the plating solution 4 is injected or optionally. The light is irradiated into the opening 21a with a time delay of At this time, since the laser 6 has a divergence angle, the opening 2
It is reflected multiple times on the inner peripheral surface of 1a and reaches the back surface of the material to be plated 2. This reflection makes the power density of the laser 6 uniform, and the material to be plated 2 is heated uniformly without causing thermal damage to the back surface. Therefore, the plating quality is uniformly improved.

The mask 21 used in the above example had a thickness of 5 mm, a diameter of the opening 21a on the laser incident side of 1 mm, and a diameter of the laser exit side of 50 μm. The laser 6 used was a YAG laser fundamental wave, second harmonic wave, and argon ion laser, and the oscillation output was 5W to 10W. Furthermore, the oscillation time is 1 for continuous waves.
The duration was 2 to 2 seconds, and the pulse wave was 2 to 3 seconds. As plating solution 4, cyan-based neutral gold plating solution is used.
The gold content was 12 g/l. The current density of plating is
It was 8A/cm2 to 15A/cm2. Nozzle 5
The distance between the tip of the plate and the material to be plated 2 is 1 mm to 5 mm.
It was mm. For example, when the above distance is 1 mm,
The diameter of the plated metal part 22 is 200 μm, the plated metal part 2
The thickness of No. 2 was 5 μm to 20 μm.

Next, an embodiment of the invention according to claim 2 will be explained with reference to the drawings. FIG. 2 is a configuration diagram showing a local plating apparatus according to an embodiment (second embodiment) of the invention according to claim 2. In the figure, a cathode 24 made of a thin film of metal such as molybdenum or gold is provided on one surface of a laser-transmissive member 23 made of a material with lower thermal conductivity than metal, such as fused silica, by vacuum deposition or plating. . This cathode 2
4 is in contact with the back surface of the material to be plated 2. Further, a mask 21 similar to that shown in FIG. 1 is in contact with the other surface of the laser transmitting member 23. Note that the nozzle 5 and lens 15 are
They are arranged in the same way as in FIG.

In such a local plating apparatus, a voltage is applied between the cathode 24 and the anode (not shown) so that a current flows through the jet 4a, and the plating solution 4 is sprayed from the tip of the nozzle 5. It is sprayed onto the plating portion of the plating material 2. 1st
Similarly to the embodiment, the laser 6 irradiated to the opening 21a of the mask 21 is reflected multiple times on the inner circumferential surface of the opening 21a and reaches the laser transmitting member 23, and the laser 6 passes through the inside of the member while diverging at a predetermined divergence angle. The cathode 24 is reached. The laser 6 irradiated to the cathode 24 heats the material to be plated 2 from the back side via the cathode 24 .

The type of laser 9, irradiation method, oscillation output, oscillation time, etc. of the second embodiment are the same as those of the first embodiment. Further, the shape of the mask 21, the type of plating solution 4, and the current density for plating are also the same as in the first embodiment. However, since the cathode 24 is provided separately from the mask 21, if the laser 6 can be reflected within the opening 21a, the mask 21
The material is not limited to conductive materials.

In the local plating apparatus of the second embodiment, as in the first embodiment, the power density of the laser 6 is made uniform by reflection within the opening 21a, so that the material to be plated 2 is heated uniformly. This improves the plating quality uniformly. Furthermore, in the apparatus of the first embodiment, since the metal mask 21 that also serves as a cathode is in direct contact with the back surface of the material to be plated 2, part of the heat applied by the laser 6 escapes to the mask 21. However, in the apparatus of the second embodiment, since the thin film cathode 24 provided on the laser-transmitting member 11 with low thermal conductivity is in contact with the material to be plated 2, the heat conduction loss of the laser 6 is small and the material to be plated is The material 2 is heated efficiently.

Although the above embodiments have been explained using electrolytic plating as an example, it goes without saying that the present invention can also be applied to electroless plating. In the case of electroless plating, the opening 21a
Ceramics and resins can also be used as mask materials by coating the mask with a laser reflective film.

[0018]

[Effects of the Invention] As explained above, the local plating apparatus of the invention according to claim 1 places a mask on the back surface of the material to be plated, and transmits the irradiated laser while reflecting it on the inner peripheral surface. Since the mask has an opening for the laser to reach the back side of the material to be plated, variations in the laser output reaching the back side of the material to be plated due to reflection within the opening are suppressed, allowing high plating speed to be maintained. This has the effect of uniformly improving plating quality. Further, in the local plating apparatus of the invention according to claim 2, a laser transmitting member is arranged on the back surface of the material to be plated, a mask is arranged on the surface of the laser transmitting member opposite to the material to be plated, and the laser beam is irradiated. Since the mask is provided with an opening for transmitting the laser while being reflected on the inner circumferential surface and reaching the laser transmitting member, in addition to the same effect as the invention according to claim 1, it is possible to use a metal mask. Even in the case where the plating material is plated, the effect is that the laser output can be efficiently applied to the material to be plated by reducing thermal conduction loss. play.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing an embodiment of the invention according to claim 1.

FIG. 2 is a configuration diagram showing an embodiment of the invention according to claim 2.

FIG. 3 is a cross-sectional view for explaining a conventional jet-type local plating method.

FIG. 4 is a cross-sectional view for explaining a conventional laser-assisted plating method.

[Explanation of symbols]

2 Plated material 4 Plating solution 4a Jet stream 6 Laser 21 Mask 21a Opening 23 Laser transmission member

Claims (2)

[Claims] 1. A local plating device that irradiates a laser onto the back surface of the material to be plated while spraying a jet of plating solution onto the plating portion of the material to be plated, wherein What is claimed is: 1. A local plating apparatus comprising: a mask having an opening for transmitting a laser beam while being reflected on an inner circumferential surface to reach the back surface of the material to be plated. 2. A local plating device that irradiates a laser beam onto the back surface of the material to be plated while spraying a jet of plating solution onto the plating portion of the material to be plated, wherein a laser transmitting device is placed on the back surface of the material to be plated. a member, and an opening disposed on a surface of the laser-transmissive member opposite to the material to be plated, for transmitting the irradiated laser while reflecting it on an inner circumferential surface to reach the laser-transmissive member. A local plating device characterized by being equipped with a mask.