JP2000064088A - Printed circuit board plating equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformly and surely stir a plating solution on the front and back surfaces of a printed circuit board, and to supply a plating solution having a uniform metal ion concentration to a surface to be plated, thereby forming a uniform surface on the printed circuit board. High precision and uniform plating on through holes. A printed circuit board P immersed in a plating solution 2
By applying a DC voltage between the printed circuit board P and the anodes 7, 7 located on both sides of the printed circuit board P and along the longitudinal direction of the printed circuit board P, a through-hole penetrating the front and back surfaces of the printed circuit board P is provided. In a printed circuit board plating apparatus in which a plating layer is formed in a hole H, an injection tube 10 having a discharge hole 9 at a predetermined position on an outer peripheral surface is disposed immediately below a printed circuit board P immersed in a plating solution 2. By injecting gas or liquid from the discharge hole 9 while rotating or reciprocating the injection tube 10 around its axis,
The plating solutions on the front and back surfaces of the printed circuit board P are alternately and uniformly stirred.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plating apparatus for a printed circuit board having through holes, and more specifically,
The present invention relates to a plating device for a printed circuit board, which uniformly stirs the plating liquid on the front and back surfaces of a printed circuit board suspended in the plating solution and supplies the plating solution with a uniform metal ion concentration to the front and back surfaces of the printed circuit board and through holes. .

[0002]

2. Description of the Related Art FIG. 4 shows a conventional plating apparatus. In the figure, 31 is a plating tank, 32 is a plating solution filled in the plating tank 31, 33 is an anode, 34 is an injection pipe for injecting bubbles to stir the plating solution, and 35 is an injection pipe 34. A bubble discharge hole formed on the peripheral surface, and 36 is an injection pipe 34.
Is a printed circuit board, and H is a through hole formed through the front and back surfaces of the printed circuit board P.

As shown in the figure, in the conventional plating apparatus, a printed circuit board P suspended in a plating solution 32 is used as a cathode (cathode), and the printed circuit board P is sandwiched in between and an anode 33 is disposed on both left and right sides thereof. A plating layer was formed in the front and back surfaces of the printed circuit board P and in the through holes H penetrating the front and back surfaces by applying a DC voltage between the plating layers 33 and 33. The anodes 33, 33 elute and supply the metal ions, which decrease as the formation of the plating layer of the printed board P progresses, into the plating solution 32.

Further, in order to remove the generated gas (H ₂ gas) adhering to the surface to be plated of the printed circuit board P, supply metal ions, and even the temperature of the plating solution, it is positioned below the printed circuit board P. Then, the plating solution 32 is agitated by ejecting air from the ejection holes 35 of the two ejection pipes 34, 34 arranged in the longitudinal direction along the front and back surfaces of the printed circuit board P.

Further, in order to form a highly accurate plating layer, it is necessary to hold the printed circuit board P suspended in the plating solution 32 as vertically as possible. To achieve this, as shown in FIG. , The supporting frame 3 by the hanging metal fitting 37
8 was suspended on the cathode bar 39, and the printed circuit board P was attached to this support frame 38.

Further, it is necessary to form a highly accurate plating layer also in the through hole H in which the holes are oriented in the horizontal direction, but conventionally, as shown by an arrow (a) in FIG. 4, as shown in FIG. The entire printed circuit board P is reciprocated in a direction orthogonal to the plate surface so that the plating solution 32 effectively flows into the through holes H.

[0007]

However, in the case of the above-described conventional plating apparatus, even if the plating solution 32 is agitated by the bubbles ejected from the two ejection pipes 34 arranged below the printed circuit board P, Since the resistance of the plating solution 32 is large, it is not possible to sufficiently ensure the uniformity of the stirring effect on the front and back surfaces of the printed circuit board P. Further, as shown in FIG. As a result, the plating solution 32 remains inclined and air bubbles wrap around only on one side of the substrate, which causes unevenness in the stirring state of the plating solution 32 on the front and back surfaces of the printed circuit board P.

To improve the above drawbacks, the printed circuit board P
The two injection pipes 34, 34 provided below the nozzles are separated from the printed circuit board P to the left and right to some extent so that the bubbles ejected from the respective injection pipes rise only on the respective surface sides of the printed circuit board P. do it. However, in the case of such a configuration, the lower end portion of the printed circuit board P is out of the stirring region, and a good stirring effect of the plating solution cannot be obtained on the entire surface of the printed circuit board.

When the agitation of the plating solution becomes non-uniform as described above, the concentration of metal ions supplied to the surface to be plated becomes non-uniform, causing a difference in the electrical resistance between the anode and the cathode, resulting in a current density of the plating current. However, there is a problem that it is not possible to obtain highly accurate and uniform plating, because it varies depending on the location.

As a measure for preventing the printed circuit board from being warped,
A guide member having a concave cross-section is fixed along the lower edge of the printed circuit board, and the printed circuit board is hung with the lower edge inside this concave shape, and the lateral movement is restricted by the concave guide member. As a result, the printed circuit board is prevented from swinging to the left and right and being agitated. However, in such a structure, the lower end portion of the printed circuit board is regulated, and therefore the arrow (a) in FIG. Since it becomes difficult to reciprocate in the horizontal direction as shown in, it is impossible to plate the inside of the through hole with high accuracy and uniformity.

The present invention has been made to solve the above problems, and uniformly and surely agitates the plating solution on the front and back surfaces of a printed circuit board to form a plating solution having a uniform metal ion concentration on the surface to be plated. An object of the present invention is to provide a plating device for a printed circuit board, which is capable of performing uniform plating with high accuracy on the front and back surfaces of the printed circuit board and through holes penetrating the front and back surfaces of the printed circuit board.

[0012]

In order to achieve the above object, the present invention provides a printed circuit board immersed in a plating solution,
A plating layer is formed in the front and back surfaces of the printed circuit board and through holes penetrating the front and back surfaces by applying a DC voltage between the anodes located on both sides of the printed circuit board and arranged along the longitudinal direction of the printed circuit board. In the printed circuit board plating device configured as described above, an injection pipe provided with a discharge hole at a predetermined position on the outer peripheral surface is provided directly below the printed circuit board immersed in the plating solution, and is arranged along the longitudinal direction of the printed circuit board. Then, by spraying gas or liquid from the discharge holes while rotating or reciprocally rotating the spray tube around its tube axis, the plating solution on the front and back surfaces of the printed circuit board is alternately agitated. is there.

It should be noted that porous partition walls permeable to metal ions are provided close to both sides of the front and back surfaces of the printed circuit board immersed in the plating solution, and the gas or liquid injected from the injection pipe is It is more preferable to rise between the partition wall and the printed board.

[0014]

[Operation] When the injection pipe is rotated or reciprocally rotated around the pipe axis and a gas such as compressed air is injected from the discharge hole or the plating solution in the plating tank is circulated, the injection pipe is rotated or reciprocated. The ejection direction and the ejection position of the gas or the liquid ejected from the ejection hole periodically change according to the rotation. Since the ejection pipe is provided directly below the printed circuit board, the gas or liquid ejected from the ejection holes is periodically moved toward the front surface side and the back surface side of the printed circuit board according to the rotation or reciprocal rotation of the ejection pipe. Are alternately jetted, and the rising gas or liquid stirs the plating solution existing near the front and back surfaces of the printed circuit board alternately and uniformly. In addition, it is possible to prevent the printed circuit board from being left inclined in the plating solution by being blown into only one surface side and being swept away by the stirring flow.

Therefore, the front and back surfaces of the printed circuit board can be uniformly and effectively stirred, and the plating solution having a uniform metal ion concentration can be uniformly supplied to the entire front and back surfaces of the printed circuit board. The front and back surfaces of can be uniformly plated.

Further, since the plating solutions on the front and back surfaces of the board are alternately agitated with the printed board as a boundary, a pressure difference is generated between the front and back surfaces of the printed board, and this pressure difference promotes convection of the plating solution in the through holes. To be done. For this reason, it is possible to plate the inside of the through hole, which is difficult to plate, with high accuracy and uniformity.

Further, since the plating solution having a high metal ion concentration is rolled up from the surroundings by the stirring and supplied to the front and back surfaces of the printed circuit board one after another, the plating solution having a high metal ion concentration can be constantly supplied. Therefore, the plating efficiency is improved and the plating speed can be increased.

It is to be noted that porous partition walls, which are permeable to metal ions, are provided close to both sides of the front and back surfaces of the printed circuit board dipped in the plating solution, and the gas or liquid sprayed from the spray tube is the partition wall. In the case of rising between the printed circuit board and the printed circuit board, the injected gas or liquid does not unnecessarily spread and dissipate, so that the above-described action can be further enhanced.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 show an embodiment of a plating apparatus according to the present invention. In the figure, 1 is a plating tank filled with a plating solution 2. At the upper end position of the plating tank 1, a plating solution recovery weir 3 for recovering the plating solution overflowing from the plating tank 1 is provided. The printed circuit board P is attached to the support frame 4 and the cathode bar is supported by the hanging metal fitting 5. It is suspended at 6. Both ends of the cathode bar 6 are held by saddles on a tank (not shown), and the saddle swings the printed circuit board P in the vertical direction and the longitudinal direction to enhance the flow of the plating solution. .

In the vicinity of the left and right wall surfaces of the plating tank 1,
The anodes 7, 7 are arranged in parallel along the longitudinal direction of the printed circuit board P. The anodes 7, 7 are connected to the anode (+) of the DC power supply for plating through the anode bars 8, 8. The cathode bar 6 is connected to the cathode (-) of the DC power supply for plating. The printed circuit board P is plated by applying a DC voltage to the cathode bar 6 and the anode bars 8 and 8.

On the other hand, a sectional shape as shown in FIG. 2 (a) or (b), in which a discharge hole 9 is provided at a predetermined position on the outer peripheral surface at a position just below the printed circuit board P suspended in the plating tank 1. The injection pipe 10 made of is disposed along the longitudinal direction of the printed circuit board P. This injection pipe 10 is rotatable about its pipe axis. By sending compressed air from an air pump (not shown) to the injection pipe 10, air is ejected from the discharge hole 9, The bubbles 11 for stirring the plating solution are configured to rise up in the plating solution.

The injection pipe 10 has its pipe end connected to a rotation or reciprocating rotation mechanism (not shown) outside the tank.
As shown in (a), it is reciprocally rotated about its axis within a range of a predetermined angle θ, or, as shown in FIG. 2 (b), is configured to rotate in one direction around its axis. Has been done. By the rotation or reciprocal rotation of the jet tube 10, the bubbles 11 jetted from the discharge hole 9 are transferred to the printed circuit board P.
It is designed to be alternately distributed to the left and right sides of the same at regular intervals.

In addition, the porous partition walls 12 permeable to metal ions are arranged near both sides of the front and back surfaces of the printed circuit board P dipped in the plating solution, and bubbles ejected from the injection pipe 10 are provided. 11 is configured to rise between the porous partition wall 12 and the printed board P. As the porous partition wall 12, a non-metal plate having a large number of fine holes 12a formed on the entire surface may be used as shown in the figure, or a fine porous porcelain plate or the like may be used. Further, the role of the porous diaphragm 12 may also be used as a current shield plate (not shown) provided to suppress the edge effect in which electricity is concentrated on the edge portion of the printed circuit board P and causes a high current density. Good.

Below the injection pipe 10 and the anodes 7 and 7, a plurality of circulation discharge pipes 13 of the plating liquid or fixed air ejection pipes are provided in order to assist the stirring of the plating liquid 2. Of the plurality of circulation discharge pipes 13, the circulation discharge pipes 13 and 1 located below the left and right anodes 7 and 7, respectively.
3 also has a role of blowing off the generated gas (H ₂ gas) adhering to the surfaces of the anodes 7 and 7 during plating at the same time as the auxiliary stirring of the plating solution 2.

The operation of the plating apparatus of the present invention having the above structure will be described with reference to the operation explanatory diagram of FIG. The printed circuit board P is positioned in the plating tank 1 and suspended in the state as shown in FIG. Further, rotation or reciprocal rotation of the injection pipe 10 is started by a rotation or reciprocating rotation mechanism (not shown), and air is started to be supplied from an air pump (not shown).
Bubbles 11 for stirring the plating solution are started to be jetted from the discharge holes 9 of the jet pipe 10. Further, the printed circuit board P is started to swing vertically and longitudinally in the plating tank 1 by a saddle on the tank (not shown), and the circulation pump (not shown) causes the circulation discharge pipe 13 to move the inside of the plating tank 1 inside the plating tank 1. Plating solution 2
Is circulated and discharged, and auxiliary stirring is started. In this state, a DC power source for plating (not shown) is turned on to start plating of the printed board P.

When the plating is started as described above,
The bubbles 11 jetted from the discharge holes 9 of the jetting pipe 10 rotating or reciprocatingly stir the plating solution on the front and back surfaces of the printed circuit board P alternately and uniformly at regular intervals.

That is, for example, the injection pipe 10 is shown in FIG.
As shown in FIG. 3A, the discharge hole 9 of the injection pipe 10 that reciprocates is shown in FIG. As shown in (b) to (b), the injection direction periodically changes according to the reciprocating rotation position of the injection pipe 10. Therefore, for example, when the discharge hole 9 faces the left side as shown in FIG. 3A, the injected bubble 11 rises along the left side surface of the printed circuit board P, and the discharge hole 9 When 9 is directed to the right as shown in FIG. 3C, the jetted bubbles 11 rise along the surface on the right side of the printed board P, and the plating solution on the front and back surfaces of the printed board P is removed. Stir evenly at regular intervals.

By the way, the bubble 11 ejected from the discharge hole 9 of the reciprocating rotating injection pipe 10 changes from the state of FIG. 3A to the state of FIG. 3B to the state of FIG. Although the state of (c) changes to the state of (a) through the state of (b), the printed circuit board P suspended at this time is supported in the direction of its rotation, and the printed circuit board P is inclined. ,
In the case of the present invention, when the bubble 11 has reached the surface on the opposite side of the printed circuit board P, this action acts to stir the printed circuit board P in a direction to push it back to the vertical position. The weight of the support frame 4 including the printed circuit board P also acts as a restoring force in the vertical direction.

Therefore, in the case of the present invention, the printed circuit board P
Even if a bubble is directly applied to the surface of the substrate from a position right below, there is no longer a tendency to tilt the printed substrate P in one direction and leave it alone. Therefore, both the front and back surfaces of the printed circuit board P can be agitated alternately in the same state, and the metal ion concentration of the plating solution 2 on both the front and back surfaces of the printed circuit board P can always be kept uniform. In addition, the printed circuit board P
Since a pressure difference is alternately generated between the front and back surfaces by the bubbles 11 that alternately wrap around the front and back surfaces, the liquid flow in the through holes H can be promoted and the inside of the through holes H can be plated uniformly.

Further, in the illustrated example, since the porous partition walls 12 that allow metal ions to pass through are arranged close to both sides of the front and back surfaces of the printed circuit board P, the bubbles 11 ejected from the ejection pipe 10 are The bubbles 11 rise up between the partition wall 12 and the printed circuit board P, and the bubbles 11 do not unnecessarily spread and dissipate, and the above-described action can be further enhanced.

In the above-described embodiment, the injection pipe 1
Although the case where the bubble 11 is sprayed from the discharge hole 9 of 0 to stir the plating solution 2 has been described, the plating solution 2 in the plating tank 1 is circulated by a circulation pump or the like to be discharged from the discharge hole 9 of the injection pipe 10. However, the same effect can be obtained.

[0032]

As described above, according to the plating apparatus of the present invention, the injection pipe provided directly below the printed circuit board is rotated or reciprocally rotated about its axis while the outer peripheral surface of the injection pipe is appropriately positioned. By injecting gas or liquid from the discharge holes provided in, the plating solution on the front and back surfaces of the printed circuit board is alternately stirred, so that the front and back surfaces of the printed circuit board can always be stirred uniformly, It is also possible that the substrate does not remain tilted to one side. Therefore, a plating solution having a uniform metal ion concentration can be supplied to the entire front and back surfaces of the printed board to perform highly accurate and uniform plating.

Further, since the flow of the plating solution in the through hole is promoted by the pressure difference which is alternately generated on the front and back surfaces of the printed circuit board, it is possible to supply the high concentration and uniform plating solution into the through hole. Therefore, it is possible to plate the inside of the through hole, which is difficult to plate, with high accuracy and uniformity.

Further, since the plating solution having a high metal ion concentration is wound from the surroundings by the agitation and is supplied to the front and back surfaces of the printed circuit board one after another, the plating solution having a high metal ion concentration is always supplied to the front and back surfaces of the printed circuit board. can do. Therefore, the plating efficiency can be improved and the plating speed can be increased.

Further, in the case where porous partition walls that allow metal ions to pass through are arranged close to both sides of the front and back surfaces of the printed circuit board, the gas or liquid sprayed from the spray tube will pass between the partition wall and the printed circuit board. Since it rises, the injected gas or liquid does not unnecessarily spread and dissipate, and the above-mentioned respective effects can be further enhanced.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view showing an embodiment of a plating apparatus according to the present invention.

2A and 2B are enlarged cross-sectional views of the injection pipe according to the above-described embodiment, FIG. 2A is a diagram showing an example of the injection pipe that reciprocally rotates in a certain angle range, and FIG. 2B is an injection that rotates in a certain direction. It is a figure which shows the example of a pipe.

3A to 3C are operation explanatory diagrams of the above-described embodiment.

FIG. 4 is a schematic vertical sectional view of a conventional device.

FIG. 5 is a schematic perspective view of a support frame portion of a printed circuit board in a conventional device.

FIG. 6 is an explanatory view of a printed circuit board in a fanned state in a conventional apparatus.

[Explanation of symbols]

1 plating tank 2 plating solution 3 Plating solution recovery weir 4 support frames 5 hanging metal fittings 6 Cathode bar 7 Anode 8 Anode bar 9 Release hole 10 injection tubes 11 bubbles 12 porous partition 12a Micropore 13 Circulation discharge pipe P printed circuit board H through hole

Claims (2)

[Claims] 1. A printed circuit board immersed in a plating solution,
A plating layer is formed in the front and back surfaces of the printed circuit board and through holes penetrating the front and back surfaces by applying a DC voltage between the anodes located on both sides of the printed circuit board and arranged along the longitudinal direction of the printed circuit board. In the plating apparatus for a printed circuit board configured as described above, an injection pipe having a discharge hole at a predetermined position on the outer peripheral surface is disposed directly below the printed circuit board immersed in the plating solution, and is arranged along the longitudinal direction of the printed circuit board. A jet or gas is then jetted from the discharge hole while the jet pipe is rotated or reciprocally rotated around the pipe axis to alternately stir the plating solution on the front and back surfaces of the printed circuit board. Substrate plating equipment. 2. A porous partition wall, which is permeable to metal ions, is provided close to both sides of the front and back surfaces of a printed circuit board immersed in the plating solution, and the gas or liquid sprayed from the spray tube is The plating apparatus for a printed circuit board according to claim 1, wherein the partition wall and the printed circuit board rise up.