JPS6116431B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electroplating device for electroplating the inner peripheral surface of a through hole for forming a through hole.

Conventionally, for example, through-holes have been formed in a double-sided printed circuit board in the following manner. That is,
First, a conductive layer is formed by chemical copper plating on the entire surface of a printed circuit board in which a hole for forming a through hole is formed, and a plating resist is printed on both sides of the printed circuit board, leaving a land area around the hole. After that, the printed circuit board is immersed in the plating solution and rocked, and a predetermined voltage is applied between the conductive layer and the anode in the plating solution, thereby removing the portions not covered with the plating resist, that is, the inside of the through holes. An electroplated layer was formed on the peripheral surface and land portions.

However, in the above method, it is difficult for the plating liquid to flow through the through-holes, so when the current density is increased to perform plating at a high speed, metal ions become depleted in the plating liquid near the through-holes. Therefore, a large amount of hydrogen gas is generated due to the discharge of hydrogen ions, leading to a decrease in current efficiency and abnormal precipitation that makes the plating locally non-uniform.This also causes the plating resist to lift up from the printed circuit board or crack. will occur. On the other hand, even if the plating liquid is allowed to flow through the through-holes, the relatively weak plating resist will rise from the substrate due to irregular precipitation caused by turbulence generated near the through-holes, which is not preferable. For this reason, in the past, it was not possible to sufficiently increase the current density, and furthermore, it was not possible to perform high-speed plating work.

The present invention has been made in view of the above circumstances, and its objects are to provide a substrate having a through hole for forming a through hole, and a mask plate that is attached to the substrate and has a liquid passage hole formed at a position corresponding to the through hole. By having a configuration in which plating is performed on the conductive layer formed on the inner peripheral surface of the through hole while flowing the plating liquid into the through hole, the current density can be increased and high speed plating work can be performed. The purpose of the present invention is to provide an electroplating device that can perform electroplating.

1 to 3 for the first embodiment of the present invention.
This will be explained with reference to the figures. Reference numeral 1 denotes a plating layer, which can be opened and closed by a container-shaped lid 2. 3
is a lower frame provided at the periphery of the opening of the plating tank 1, and a support step 3a is formed on the inner circumference side of the lower frame, and the first mask plate 4 is fitted and fixed to this support step 3a in a liquid-tight manner. are doing. Reference numeral 5 designates an upper frame provided at the periphery of the opening of the lid 2, which also has a stepped portion 5a similar to the lower frame 3, and a second mask plate 6 is fitted into this stepped portion 5a in a fluid-tight manner. It is fixed. 7 is a rubber sheet for sealing that is attached to the upper and lower surfaces of the first and second mask plates 4 and 6, respectively, and has a hardness of, for example, 60° to 150°.
Made of hard rubber. Reference numeral 8 denotes a board made of a double-sided copper-clad laminate in which copper foil 8b is adhered to both sides of a board 8a made of, for example, a glass epoxy board.
The mask plate is placed in the plating tank 1 and is sandwiched between the first and second mask plates 4 and 6 so that it can be attached and detached. And this board 8
For example, a through hole 9 for forming a through hole is drilled at a predetermined position using an NC drilling machine, and a conductive layer 10 is formed on the entire surface including the inner peripheral surface of the through hole 9 by chemical copper plating. The first and second mask plates 4 and 6 are made of glass epoxy plates made of the same material as the base material of the substrate 8, and
A liquid passage hole 1 having the same diameter as the through hole 9 or having a slightly larger diameter to form a land is located at a position corresponding to each through hole 9.
1 is formed. These liquid passage holes 11 were drilled using an NC drilling machine in the same way as the through holes 9, and were drilled using NC tape that was the same as that used for drilling the through holes 9 or with only the hole diameter changed. 1
The formation position of the hole 1 is made to match that of the through hole 9 with high precision. Reference numeral 12 denotes a plating liquid tank for storing plating liquid 13. This plating liquid 13 is supplied into the plating tank 1 by a high-pressure pump 14, and passes through the liquid passage holes 11 of the mask plates 4 and 6 and the through holes 9 of the substrate 8. It passes through the lid 2 and returns to the plating liquid tank 12 from inside the lid 2 via a circulation pipe 15. Reference numeral 16 denotes a perforated titanium plate disposed within the plating tank 1, which is located near the first mask plate 4 and is provided so as to face substantially parallel to the mask plate 4. 17 is an anode disposed at the bottom of the plating tank 1; 18 is a cathode side lead wire provided in contact with the conductive layer 10 of the substrate 8; these anode 17 and lead wire 18 are connected to a plating power supply 19;
are connected.

Next, the operation of the above configuration will be explained. First, the lid 2 is opened and the substrate 8 is placed on the first mask plate 4.
The lid 2 is closed so that the substrate 8 is sandwiched between the first and second mask plates 4 and 6. In this state, the through hole 9 of the substrate 8 and the liquid passage hole 11 of each of the first and second mask plates 4 and 6 are aligned. After that, when the high-pressure pump 14 is started, the plating liquid 13 in the plating liquid tank 12 fills the plating tank 1, and in the process of passing through the perforated plate 16, the plating liquid 13 flows upward with a substantially constant force over the entire area. The liquid flows at high speed through each of the liquid passage holes 11 of the first and second mask plates 4 and 6 and each of the through holes 9 of the substrate 8 and is ejected into the lid 2. When the plating power supply 19 is turned on and a predetermined voltage is applied between the anode 17 and the conductive layer 10 of the substrate 8 at approximately the same time as the plating liquid flows through the through holes 9, the plating liquid flows into the through holes 9. During the process of flowing through the conductive layer 10 of the substrate 8, a plating layer 20 is formed on the portions of the conductive layer 10 of the substrate 8 that are not covered by the first and second mask plates 4 and 6, that is, on the inner peripheral surface of the through hole 9 and on the land portion. (See Figure 3). After this, turn off the power supply device 19 for metsuki,
The high-pressure pump 14 is stopped, the lid 2 is opened, and the substrate 8 is taken out.

According to the above embodiment, since new plating liquid 13 can be constantly supplied at high speed to the part where the plating layer 20 is to be formed, the metal ion concentration of the plating liquid near the plating part decreases, unlike the conventional method. It is possible to prevent hydrogen gas from being generated, and as a result, the current density can be sufficiently increased and plating can be performed at high speed. Incidentally, in conventional plating equipment, a maximum of about 1.5 to 2.5 A/dm ² is required to form a copper plating layer of about 30μ in the through hole 9 for through hole formation.
However, in this embodiment, when the speed of the plating liquid 13 flowing through the through holes 9 is set to about 5 to 30 m/min, the current density is reduced to about 40 to 60 minutes.
10 to 50 A/dm ² , and the time required to form a copper plating layer of the same thickness as the conventional one was about 2 to 6 minutes. Furthermore, since the first and second mask plates 4 and 6 are sufficiently strong compared to conventional printed plating resist layers, the plating liquid 13 can be applied to the through holes 9.
Even if the mask plates 4 and 6 are allowed to flow at high speed, the turbulence generated on the inflow and outflow sides of the through hole 9 will not break the mask plates 4 and 6, nor will they float up from the substrate 8. Moreover, the first and second mask plates 4, 6
Since it can be used repeatedly, when plating a large number of substrates 8 of the same type, the plating cost can be significantly reduced compared to the conventional method in which plating resist needs to be printed one by one for each substrate.
In addition, since the parts to be electroplated were the inner periphery of the through hole and the land part for forming the through hole,
Since the plating area is extremely small and has the same shape, the plating thickness distribution can be made extremely uniform, and the quality can be significantly improved.

Furthermore, especially if the perforated plate 16 is disposed in the plating tank 1 near the first mask plate 4 as in this embodiment, the plating liquid 1 is supplied by the high-pressure pump 14.
3 is discharged into the plating tank 1 with a strong force, causing turbulent flow within the plating tank 1, this perforated plate 16 prevents the local discharge pressure of the high pressure pump 14 from reaching the substrate 8. In addition, the speed of the plating plate 13 flowing through it can be made uniform over the entire area of the substrate 8, and the thickness of the plating layer 20 can be made as uniform as possible within one through hole 9 and for each through hole 9. can. In addition, in this embodiment, the perforated plate 1
6 is simply arranged in the vicinity of the first mask plate 4 to face it, but a positive potential lower than that of the anode 17 may be applied to the conductive layer 10 of the substrate 8 to this porous plate 16. . In this way, the plating layer 20 can be formed with a more substantially uniform thickness for the through holes 9 formed at any position on the substrate 8. This is because when no positive potential is applied to the porous plate 16, the distribution of electric lines of force between the substrate 8 and the anode 17 tends to become denser toward the periphery of the substrate 8, as described above. If a positive potential lower than that of the anode is applied to the porous plate 16, the substrate 8
This is thought to be because the distribution of electric lines of force on the surface can be made as uniform as possible between the central part and the peripheral part.

Moreover, in this embodiment, since the materials of the first and second mask plates 4 and 6 are made the same as the material of the base material of the substrate 8, the first and second mask plates 4 and 6 and the substrate 8 are made of the same material. The expansion and contraction rates due to temperature changes or moisture absorption are equal. As a result, the substrate 8, mask plate 4,
Misalignment between the through hole 9 and the liquid passage hole 11 due to expansion and contraction of the liquid passage hole 6 can be prevented. Note that the diameter of the through hole 9 and the liquid passage hole 11 is relatively large, or the through hole 10 is relatively large in diameter.
If positional accuracy is not required, they do not necessarily need to be made of the same material.

4 and 5 show a second embodiment of the present invention, and the difference from the above embodiment is that a so-called flexible printed circuit board 2 having flexibility as a substrate.
0, and the drum 2 installed on one side of the plating tank 1.
1, the long strip-shaped flexible printed circuit board 2
0 is wound up and passed between the first and second mask plates 4 and 6 of the plating layer 1 and wound up by a winding drum 22 provided on the other side of the plating tank 1. . This flexible printed circuit board 20 has 9 groups of through holes formed in advance for forming a large number of through holes, and these 9 groups of through holes form 11 groups of liquid passage holes formed in the first and second mask plates 4 and 6. The flexible printed circuit board 20 is intermittently wound up on the winding drum 22, and the high pressure pump 14
This is to operate the plating power supply device 19.

In each of the above embodiments, the rubber sheets 7 for sealing are attached to the first and second mask plates 4 and 6, respectively, but these may be provided as needed.
In addition, the present invention is not limited to the embodiments described above and shown in the drawings. For example, the lid 2 of the plating tank 1
A detection electrode may be provided to detect the ejection of the plating liquid, and the plating power supply 19 may be activated at the same time as this detection electrode detects that the plating liquid has flowed through the through holes 9 of the substrates 8, 20. Alternatively, a voltage may be applied before the plating liquid passes through so that a current flows as the plating liquid flows.Furthermore, the anode 17 may be disposed not only in the plating tank 1 but also in the lid 2. The invention can be implemented with various changes without departing from the scope of the invention.

As described above, the present invention includes a substrate having a through hole for forming a through hole, a mask plate that is attached to this substrate and has a liquid passage hole formed at a position corresponding to the through hole, The feature is that plating is performed on the conductive layer formed on the inner peripheral surface of the through hole while the plating liquid is flowing inside the hole.As a result, new plating liquid is constantly supplied inside the through hole. This has the excellent effect of increasing the current density, allowing plating to be performed at high speed, and reducing the plating cost by repeatedly using the mask plate.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, FIG. 1 is an overall vertical cross-sectional view, FIG. 2 is an enlarged vertical cross-sectional view of the substrate and mask plate, and FIG. 3 is a state after plating. FIG. 4 and FIG. 5 show the second embodiment of the present invention, and FIG. 4 is a diagram equivalent to FIG.
FIG. 5 is a partial plan view of the flexible printed circuit board. In the figure, 4 and 6 are first and second mask plates, 8,
20 is a substrate, 9 is a through hole, 10 is a conductive layer, 11 is a liquid passage hole, 13 is a plating liquid, and 16 is a porous plate.

Claims (1)

[Claims] 1. A substrate having a through hole for forming a through hole;
A mask plate is provided on the substrate and has a liquid passage hole formed at a position corresponding to the through hole, and a conductive layer formed on the inner circumferential surface of the through hole while allowing plating liquid to flow through the through hole. An electric plating device characterized in that it applies plating to. 2. The electroplating apparatus according to claim 1, wherein a perforated plate is provided near the plating liquid inflow side of the substrate and facing the substrate.