JP2905664B2 - Printed wiring board etching method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an etching control method for optimally controlling an etching amount in a printed wiring board etching process.

[0002]

2. Description of the Related Art Generally, in forming a pattern of a printed wiring board by etching, the size of an etching resist is as follows.
It is designed with a correction slightly larger than the size of the pattern to be obtained. This means that during etching, the etching proceeds to below the resist (side etching)
That's why. Usually, the amount of side etching is about the same as the thickness of the pattern to be etched.

In an actual printed circuit board process, if the etching conditions are inappropriate and the amount of side etching is smaller than designed, an unetched portion occurs between the patterns and a short circuit occurs. In this case, the space between the patterns becomes narrow, which adversely affects the insulation characteristics between adjacent patterns. Conversely, when the side etching amount is larger than the design value, the pattern width becomes smaller than the design value, and the electric resistance of the pattern increases and the pattern disconnection occurs.

[0004] In particular, in the case of a pattern whose design value is narrow from the beginning, the influence of the decrease in the pattern width becomes greater.

[0005]

By the way, in recent years, high-density wiring has been required for a wiring board due to improvement in mounting density and reduction in size of the printed wiring board, and a finer pattern than before has been required. For this reason, it is necessary to reduce the pattern pitch, and the design value of the pattern width is reduced to about several times the thickness of the metal foil used as the pattern conductor. Since the pattern width is reduced, the side etching amount becomes relatively nonnegligible, and it is necessary to strictly control the process.

Conventionally, as a method of monitoring the etching state of such a fine pattern, a method of taking out a single substrate from a production line in a process and measuring the pattern size by a microscope or the like has been adopted.

However, in such a conventional management method,
It is difficult to manage the etching state of the substrate smoothly in the flow of the process, which requires time and effort, increases the work time, and increases the cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide an etching control method which can easily confirm the etching state of a pattern on a production line, can simplify the operation steps, and can reduce the cost.

[0009]

In order to achieve the above object, the present invention provides a method for etching a printed wiring board in which a conductor laminated on a substrate is etched by a resist provided on the conductor to obtain a wiring portion. A test pattern portion, in which a plurality of resists having different sizes in a stepwise manner are arranged in a line at the same interval, is provided at a position different from the wiring portion of the substrate, and the resist pattern is etched when the test pattern portion is etched. In which the state of etching is controlled by observing the disappearance of the resist.

[0010]

When the etching is performed using the resist having the above-described shape, the smaller resist is removed by the side etching at a shorter time than the larger resist, together with the underlying conductor. On the other hand, the side of the larger resist is also removed by side etching, but is not completely removed. Therefore, when the test pattern is observed from the upper surface during the etching, the portion where the resist remains and the portion where the resist has been removed can be clearly distinguished.

As described above, in the present invention, the etching state can be confirmed only by visually checking the test pattern.
Therefore, even during the production line process, the etching state can be known by observing the vanishing point of the test pattern from above, and it is necessary to lower the substrate from the production line in order to observe the etching state as in the conventional case. There is no. As described above, according to this embodiment, the etching process can be greatly simplified, and the cost can be reduced.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. FIGS. 1 (a) and (b) respectively show
FIGS. 2A and 2B are a top view and a side view of a test pattern (hereinafter simply referred to as a test pattern) portion for determining a side etching amount according to the present embodiment, respectively. It is the top view and side view of FIG. However, as described later in the top view of FIG.
In addition to the shape of the conductor, the outer shape of the resist for comparison with the conductor is shown.

FIG. 1 shows a test pattern portion of this embodiment.
As shown in (a) and (b), a plurality of etching resists (hereinafter simply referred to as resists) 3 serving as test patterns are formed on a conductor 2 formed on the entire surface of a printed circuit board 1 in a direction A. The width is provided so as to be narrower. The gaps 4 between the resists 3 are all the same width.

When etching is performed using the etching resist 3 having the above-described shape, as shown in FIGS. 2A and 2B, the narrower resist 3 is larger than the wider resist 3. Then, the conductors 2 thereunder are removed by the side etching 5 at an early time. On the other hand, the side of the wider resist 3 is also removed by the side etching, but is not completely removed.

Therefore, when this test pattern is observed from the upper surface at the time of etching, a portion B where the resist remains is obtained.
And the portion C from which the resist has been removed can be clearly identified. 3 and 4 are top views of the same test pattern portion as FIG. 2, and show a case where side etching is insufficient and a case where side etching is excessive, respectively.

As described above, by confirming the width of the resist 3 remaining after the etching, the amount of side etching can be visually determined without directly measuring the amount of side etching.

FIGS. 5 to 8 are top views showing examples in which a large number of the test patterns are provided on the outer periphery of the work of the printed circuit board, which are before etching, ideally etched, excessively etched, and insufficiently etched. The state of is shown. In the figure, 6 is each printed circuit board, 7 is a wiring section, and 8 is a test pattern section.

Here, the test pattern section 8 is provided on the same substrate as the wiring section 7, and the material and thickness of the conductor and the resist are the same in both sections. Further, as a condition set in advance, the resist width of each resist is determined so that the resist is removed together with the conductor therebelow at the center of the test pattern 8 and disappears when the ideal side etching amount is obtained.

In the above structure, the etching is started from the state shown in FIG. 5, and the etching is performed until the state shown in FIG. 6, that is, when the resist is removed up to the arrow D when viewed from the top, and the etching is stopped there. By
An ideal amount of side etching designed in advance can be performed.
On the other hand, FIGS. 7 and 8 show examples of excessive side etching (removed up to arrow E) and insufficient side etching (removed up to arrow F), respectively.

As described above, according to this embodiment, the etching state can be confirmed only by visually observing the test pattern from above. Therefore, in the related art, it was difficult to observe the etching state of the substrate flowing on the production line while being placed on the production line, but according to the present embodiment, even during the production line process, Ideal side etching can be realized only by observing the vanishing point of the test pattern from above and stopping the etching when the vanishing point reaches the center. As described above, according to the present embodiment, the amount of side etching can be easily and clearly known, the etching process can be greatly simplified, and the cost can be reduced.

In this embodiment, a test pattern in which a plurality of vertically long resists having different widths are arranged as described above is used, but the shape is not limited to this.
For example, a circular pattern 9 as shown in FIG. 9A may be used, and the diameter may be changed stepwise and arranged.

Also in this example, as shown in FIG. 9B, the side etching amount can be known by utilizing the disappearance of the small circular pattern 9 together with the conductor 2 thereunder after etching. The process can be simplified and costs can be reduced.

[0023]

As described above, according to the present invention, in the etching process of a printed wiring board, the etching state can be easily and clearly known only by observing the upper surface of the printed wiring board. Therefore, it is possible to provide an etching control method for a printed wiring board that can perform etching control while flowing the printed wiring board in a production line, thereby simplifying an etching process and reducing costs.

[Brief description of the drawings]

FIGS. 1A and 1B are a top view and a side view of a test pattern unit according to an embodiment of the present invention, respectively.

FIGS. 2A and 2B are a top view and a side view, respectively, during the etching of a test pattern portion according to an embodiment of the present invention.

FIG. 3 is a top view showing a state where etching is insufficient in the test pattern portion of FIG. 1;

FIG. 4 is a top view showing a state of excessive etching in the test pattern portion of FIG. 1;

FIG. 5 is a top view showing an example in which a test pattern portion according to an embodiment of the present invention is provided on the outer periphery of a work of a multi-spelled printed wiring board.

FIG. 6 is a top view showing a state where ideal etching has been performed on the printed wiring board of FIG. 5;

FIG. 7 is a top view showing a state in which etching is excessive in the printed wiring board of FIG. 5;

FIG. 8 is a top view showing a state where etching is insufficient in the printed wiring board of FIG. 5;

FIGS. 9A and 9B are top views showing a test pattern portion before and after etching according to another embodiment of the present invention, respectively.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Board 2 Conductor 3 Resist 7 Wiring part 8 Test pattern part

Claims (1)

(57) [Claims] 1. A method for etching a printed wiring board, wherein a conductor laminated on a substrate is etched by a resist provided on the conductor to obtain a wiring portion, Provide a test pattern portion in which a plurality of resists of different sizes are arranged in a line with the same interval between each, and observe the disappearance state of the resist when etching the test pattern portion to manage the etching state. A method for etching a printed wiring board.