JP2010129696A - Method of manufacturing wiring circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a wiring circuit board capable of accurately determining the existence of the defects of wiring patterns. <P>SOLUTION: A predetermined wiring pattern is formed (step S1). Subsequently, the automatic optical inspection of the wiring patterns is performed by an appearance inspection device (step S2). Successively, an electroless tin plating layer is formed, in such a manner as to cover the wiring pattern to perform the surface treatment of the wiring pattern (step S3). Then, the part of the defect of the wiring pattern detected by an AOI is imaged by an imaging device, such as CCD, and an operator verifies the result of the AOI on the basis of the image (step S4). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a printed circuit board.

Conventionally, when a printed circuit board is manufactured, an automatic optical inspection (AOI) for detecting a defect in the wiring pattern is performed at a semi-finished product stage after the wiring pattern is formed. After the AOI, the operator confirms (verifies) the inspection result (see, for example, Patent Document 1). Specifically, the part of the wiring pattern in which a defect is detected in the AOI is imaged by a CCD (charge coupled device) or the like. Based on the image, the operator visually determines whether or not the portion where the defect is detected actually has a defect. If there is actually a defect, the semi-finished product is recognized as a defective product and is subject to disposal or repair. If there are no defects, the semi-finished product is recognized as a non-defective product, and processing continues.
JP 2001-356099 A

  When, for example, copper is used as the wiring pattern material, a part of the surface of the wiring pattern may be oxidized and discolored. Usually, such discoloration does not affect the characteristics of the wiring pattern and does not cause a defect.

  In AOI, discoloration due to oxidation of the wiring pattern is detected as a defect. In this case, even in the verification after AOI, the operator may erroneously determine that the discoloration due to oxidation is a defect. This is because it is difficult to distinguish discoloration due to oxidation from actual defects such as dents, chips, or disconnections on an image for verification. As a result, an excessive number of semi-finished products that are recognized as defective products are generated, and productivity is reduced.

  The objective of this invention is providing the manufacturing method of the printed circuit board which can recognize correctly the presence or absence of the defect of a wiring pattern.

  (1) In the method for manufacturing a printed circuit board according to the present invention, a step of forming a wiring pattern on the substrate and a visual inspection of the wiring pattern by an inspection apparatus are performed to detect a possible defect in the wiring pattern. Obtained by the step of forming, the step of forming the surface treatment layer on the wiring pattern after the appearance inspection, the step of imaging the portion of the wiring pattern detected by the appearance inspection after the formation of the surface treatment layer, and the step of imaging A step of visually checking whether or not the wiring pattern portion detected by the appearance inspection actually has a defect on the image.

  In this method of manufacturing a printed circuit board, after a wiring pattern is formed on the substrate, an appearance inspection of the wiring pattern is performed by an appearance inspection. Thereby, the part with the possibility of a defect in a wiring pattern is detected. After the appearance inspection by the appearance inspection, a surface treatment layer is formed on the wiring pattern. Thereafter, the portion of the wiring pattern detected by the appearance inspection is imaged, and it is visually confirmed on the image whether or not the portion of the wiring pattern detected by the appearance inspection is actually defective.

  In this case, the wiring pattern is exposed during the appearance inspection by the inspection apparatus. Thereby, a fine inspection can be performed and a defect detection failure can be prevented.

  The visual confirmation is performed based on an image in a state where the wiring pattern is covered with the surface treatment layer. Therefore, even if the wiring pattern is discolored due to oxidation, the portion is not recognized as a defect when visually confirmed.

  Therefore, even if the portion of the wiring pattern discolored due to oxidation is detected as a portion having a possibility of defect during the appearance inspection by the inspection apparatus, it is recognized that the portion is free of defects when visually confirmed. As a result, a semi-finished product that is actually free of defects is prevented from being processed as a defective product, and the productivity of the printed circuit board is improved.

  (2) The material of the surface treatment layer may have higher oxidation resistance than the material of the wiring pattern.

  In this case, the surface treatment layer is prevented from being oxidized and discolored before visual confirmation. This prevents the portion of the surface treatment layer that has been oxidized and discolored from being erroneously recognized as a defect.

  Further, since the wiring pattern is covered with the surface treatment layer having high oxidation resistance, the wiring pattern is prevented from being oxidized, and thus the deterioration of the characteristics of the wiring pattern is prevented.

  (3) The wiring pattern may include copper, and the surface treatment layer may include at least one of tin and nickel.

  In this case, oxidation of the surface treatment layer and the wiring pattern is prevented. In addition, electrical connectivity between the wiring pattern and other electronic components can be improved.

  (4) The method for manufacturing a printed circuit board further includes a step of preparing a first insulating layer as a substrate and a step of forming a second insulating layer so as to cover the wiring pattern after the step of visual confirmation. May be.

  In this case, the wiring pattern is protected from the external environment by the second insulating layer. Thereby, deterioration of the characteristics of the wiring pattern is prevented.

  According to the present invention, even when a portion of the wiring pattern discolored due to oxidation is detected as a portion having a possibility of defect at the time of appearance inspection by the inspection apparatus, it is recognized that the portion is not defective at the time of visual confirmation. Is done. As a result, a semi-finished product that is actually free of defects is prevented from being processed as a defective product, and the productivity of the printed circuit board is improved.

  Hereinafter, a method for manufacturing a printed circuit board according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a flowchart showing an outline of a method for manufacturing a printed circuit board according to the present embodiment. FIG. 2 is a cross-sectional view showing an example of a manufacturing process of the printed circuit board according to the present embodiment.

  First, a predetermined wiring pattern is formed (step S1 in FIG. 1).

  Specifically, as shown in FIG. 2A, a metal substrate 10 made of, for example, stainless steel is prepared. The thickness of the metal substrate 10 is, for example, 5 μm or more and 50 μm or less, and preferably 10 μm or more and 30 μm or less. As a material of the metal substrate 10, other metal such as aluminum or an alloy may be used instead of stainless steel.

  Next, as shown in FIG. 2B, a base insulating layer 12 made of, for example, polyimide is formed on the metal substrate 10. The base insulating layer 12 is an example of a first insulating layer. The thickness of the base insulating layer 12 is, for example, not less than 1 μm and not more than 15 μm, and preferably not less than 2 μm and not more than 5 μm. As the material of the base insulating layer 12, other insulating materials such as epoxy may be used instead of polyimide.

  Next, as shown in FIG. 2C, a predetermined wiring pattern 13 made of, for example, copper is formed on the base insulating layer 12. The thickness of the wiring pattern 13 is, for example, 3 μm or more and 16 μm or less, and preferably 6 μm or more and 13 μm or less. The wiring pattern 13 may be formed using, for example, a semi-additive method, or may be formed using another method such as a subtractive method. The material of the wiring pattern 13 is not limited to copper, and other metals such as gold (Au) and aluminum, or alloys such as copper alloy and aluminum alloy may be used.

  After the predetermined wiring pattern 13 is formed in this way, automatic optical inspection (AOI) is performed on the wiring pattern 13 by an appearance inspection apparatus (not shown) (step S2 in FIG. 1).

  Specifically, an image indicating the normal state of the wiring pattern 13 is stored in advance in the appearance inspection apparatus as image data. A portion of the wiring pattern 13 that is different in color, shape, etc. from the state indicated by the stored image data is detected as a defect.

  Subsequently, as shown in FIG. 2D, an electroless tin plating layer 14 is formed so as to cover the wiring pattern 13, and the surface treatment of the wiring pattern 13 is performed (step S3 in FIG. 1). With this surface treatment, when an electronic component (not shown) is mounted on the printed circuit board, the connectivity between the wiring pattern 13 and the electronic component can be sufficiently ensured.

  The tin plating layer 14 is an example of a surface treatment layer. Here, as the material of the surface treatment layer, it is preferable to use a metal or alloy having higher oxidation resistance than the material of the wiring pattern 3 made of copper. The thickness of the tin plating layer 14 is, for example, 2 μm or less, and preferably 0.1 μm or more and 1 μm or less. Instead of the tin plating layer 14, a layer made of another material such as a nickel plating layer may be formed.

  Next, a defective portion of the wiring pattern 13 detected in the AOI is imaged by an imaging device such as a CCD (Charge Coupled Device) (not shown), and the operator confirms (verifies) the AOI result based on the image. (Step S4 in FIG. 1).

  In the AOI, a pseudo defect that is not actually a defect may be detected as a defect. Here, the pseudo defect refers to an appearance defect that does not affect the characteristics. For example, discoloration due to oxidation of the wiring pattern 13 is a pseudo defect and not an actual defect, but is detected as a defect in the AOI.

  At the time of verification, the operator visually determines whether the defect detected in the AOI is an actual defect or a pseudo defect. Then, the operator distributes the semi-finished product determined as not an actual defect (the state shown in FIG. 2D) as a non-defective product, and distributes the semi-finished product determined as an actual defect as a defective product (step S5 in FIG. 1). .

  The semi-finished product that has been distributed as a non-defective product is subsequently processed according to the manufacturing process (step S6 in FIG. 1). For example, as shown in FIG. 2E, a cover insulating layer 15 made of polyimide, for example, is formed on the base insulating layer 11 so as to cover the wiring pattern 13 and the electroless tin plating layer 14. The insulating cover layer 15 is an example of a second insulating layer. The thickness of the insulating cover layer 15 is, for example, 4 μm or more and 26 μm or less, and preferably 5 μm or more and 21 μm or less. As the material of the insulating cover layer 15, other insulating materials such as epoxy may be used instead of polyimide. Thereby, the printed circuit board 1 is completed.

  On the other hand, processing such as disposal or repair is performed on the semi-finished product distributed as a defective product (step S7 in FIG. 1).

  Thus, in the present embodiment, the surface treatment of the wiring pattern 13 is performed before the verification of the AOI result. In this case, the portion of the wiring pattern 13 discolored by oxidation is covered with the electroless tin plating layer 14. This prevents the operator from erroneously recognizing the discoloration of the wiring pattern 13 as a defect. Therefore, the number of semi-finished products that are mistakenly assigned to defective products can be reduced, and productivity can be improved.

  Further, the surface treatment of the wiring pattern 13 is performed after the AOI. That is, at the time of AOI, the wiring pattern 13 is exposed. In this case, since the exposed surface of the wiring pattern 13 is in a mirror surface state, it becomes possible to perform a finer inspection in the AOI. Thereby, it is possible to reliably prevent the occurrence of defect detection failure.

  In addition, when a plurality of semi-finished products are connected in a long shape, it is difficult to sort good products from defective products before the manufacturing process (in this example, the formation of the cover insulating layer 11) performed after verification. It becomes. In that case, for example, an identification mark may be formed on a semi-finished product having a defect, and after the manufacturing process after verification is completed, a non-defective product and a defective product may be sorted based on the identification mark.

  In this case, it is not necessary to distribute the non-defective product and the defective product after completion of the manufacturing process. That is, a product in a state where a good product and a defective product are connected is completed. In this case, since the non-defective product and the defective product can be determined by the identification mark, only the non-defective product can be selected and used.

  The present invention can be applied to the manufacture of various printed circuit boards such as a flexible printed circuit board or a rigid printed circuit board.

  The present invention can be effectively used for manufacturing various printed circuit boards.

It is a flowchart which shows the outline | summary of the manufacturing method of the printed circuit board which concerns on this Embodiment. It is sectional drawing which shows an example of the manufacturing process of the printed circuit board which concerns on this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wiring circuit board 10 Metal substrate 12 Base insulating layer 13 Wiring pattern 14 Tin plating layer 15 Cover insulating layer

Claims (4)

Forming a wiring pattern on the substrate;
A step of detecting a possible defect in the wiring pattern by performing an appearance inspection of the wiring pattern by an inspection device;
Forming a surface treatment layer on the wiring pattern after appearance inspection;
Imaging the portion of the wiring pattern detected by appearance inspection after the surface treatment layer is formed;
And a step of visually checking whether or not the portion of the wiring pattern detected by the appearance inspection actually has a defect on the image obtained in the imaging step. Production method. 2. The method of manufacturing a printed circuit board according to claim 1, wherein the material of the surface treatment layer has higher oxidation resistance than the material of the wiring pattern. 3. The method for manufacturing a printed circuit board according to claim 2, wherein the wiring pattern includes copper, and the surface treatment layer includes at least one of tin and nickel. Preparing a first insulating layer as the substrate;
The method for manufacturing a printed circuit board according to claim 1, further comprising a step of forming a second insulating layer so as to cover the wiring pattern after the visual confirmation step. .

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