JP2010094741A - Method for deciding quality of through-hole - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for deciding the quality of a through-hole, capable of providing information for maintenance inspection of a laser beam machining apparatus by respectively inspecting holes which are formed on green sheets by laser beam machining to find whether there are imperfect holes or non-through-holes etc. or not. <P>SOLUTION: In the method for deciding the quality of the through-hole, the hole feature value of an opening for each part in which a through-hole is formed by laser beam machining is obtained by image processing and whether maintenance inspection of the laser beam machining apparatus is necessary or not is decided based on continuity of occurrence of the hole having approximately the same hole feature value. The hole feature value is defined by an area or an average diameter of the opening. It is preferable to decide whether the maintenance inspection of a through-hole forming device is necessary or not based on continuity of occurrence of the through-hole whose hole feature value is lower than a predetermined threshold. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for determining the quality of through holes formed in a sheet material such as a green sheet, and more particularly to a method for determining the quality of through holes formed by laser processing.

  A multilayer component such as a multilayer chip capacitor is manufactured by laminating and firing ceramic green sheets on which a conductor pattern is printed. In many cases, a conductor pattern printed on a green sheet is electrically connected between a plurality of layers, and a through hole connected to the conductor pattern is formed at a predetermined position in the green sheet. Since electrical connection is performed by embedding a conductor in the through hole, the quality of the through hole greatly affects the quality of the laminated part, and maintenance inspection of the through hole forming tool is important.

  For the formation of through-holes (hereinafter abbreviated as holes), a conventional mechanical method using punching pins has been used. However, the punching pins are very small in diameter and easy to break, and green sheet ceramic particles and green sheets The cutting edge is worn by the carrier film that holds When the punching pin is broken, no hole is formed at all, resulting in complete conduction failure. When the cutting edge is worn, burrs or the like are generated, making it difficult to embed the conductor, resulting in poor conduction reliability.

  Various proposals have been made to solve the above problems. For example, Patent Document 1 below discloses a method of providing an impact sensor on each punch pin. That is, when the hitting sensor detects, it is determined that the punching pin has penetrated the green sheet and has been normally punched, and when not detected, it is determined that the punching pin is broken. Further, for example, Patent Document 2 below discloses a method for managing the tool life by determining the number of times the tool can be used in advance and comparing it with the integrated value of the actual number of times of use. Further, in Patent Document 3 below, a green sheet is sandwiched between a transmission sensor composed of a light emitting part and a light receiving part, and a light reception level of total light passing through a plurality of holes included therein is detected in a predetermined area unit, A method is disclosed in which the presence or absence of a non-through hole is optically determined by comparing with a determination level, and a tool breakage is detected.

JP 60-148700 A Japanese Examined Patent Publication No. 4-51249 JP-A-4-300200

The method of Patent Document 1 can be detected when the punching pin is completely broken and does not press the green sheet. However, when the punching pin or the die hole is worn, the punching pin shaft center and the mold are provided. If the axial center of the punching die hole into which the punching pin is fitted is shifted, the punching pin penetrates the green sheet, so that it is determined that the punching is normal. However, the formed hole is an incomplete hole in which a burr protrudes from the opening, and the reliability of conduction becomes a problem. Thus, there is a problem that wear of the punching tool, poor adjustment, etc. cannot be detected, and that the attachment of the hitting sensor becomes complicated when the number of punching pins increases.
In the method of Patent Document 2, the tool life must be set according to the properties (for example, thickness and material) of the object to be drilled, and the life of the tool itself varies and the mounting state of the tool is different. Depending on the tool life, the tool life changes, and it is difficult to determine an appropriate number of times to use. Moreover, it cannot cope with sudden damage.

Moreover, the method of patent document 3 is compared with the determination level with respect to the total light which passes a some hole, determines the presence or absence of a non-through hole, and does not evaluate each hole. Therefore, when the number of target holes in the inspection area is small, the light reception level difference between when there is a non-through hole and when there is no non-through hole is large, so the determination is easy. Since it becomes smaller, it is difficult to set the judgment level, and there is a risk of missing a non-through hole. In addition, as described above, for incomplete holes where burrs are generated due to wear, etc., rather than tool breakage, since the light reception level varies with each drilling, setting the judgment level is further difficult and incomplete It is difficult to determine the presence or absence of holes. In this way, it is difficult to set the judgment level even if the number of target holes in the inspection area is constant. In addition, if the number of holes changes, the judgment level must also be changed. Is difficult.
Recently, instead of the mechanical punching pin method, a method of making a hole by irradiating a laser is also used, but the above-mentioned known example cannot cope with it.

  Therefore, the object of the present invention is to perform quality inspection that can provide information for maintenance inspection of laser processing equipment by inspecting each hole formed by laser processing on the green sheet for the presence or absence of incomplete holes or non-through holes. Is to provide a method.

According to the present invention, the hole feature amount of the opening is obtained by image processing for each part where a through hole should be formed by laser processing, and the maintenance inspection of the laser processing apparatus is performed based on the continuity of the generation of holes having the same hole feature amount. It is characterized by determining whether or not is necessary.
In the present invention, whether or not the hole feature is the area or average diameter of the opening, and maintenance of the through-hole forming tool is necessary based on the continuity of occurrence of the through-hole where the hole feature is below a predetermined threshold Is preferably determined.

  As described above, the openings of a large number of holes formed by laser processing are quantitatively evaluated individually, and the data processing is performed by appropriately adding the generated position information. This makes it possible to accurately determine the maintenance inspection time, and the quality of the holes formed in the green sheet can always be maintained in a good state. In addition, when a defective hole that causes a product defect occurs, information can be output at an early stage, which is effective in improving productivity.

It is a flowchart showing the concept of the present invention. It is a main part structure of a drilling device. It is a schematic diagram of the drilled green sheet. It is a figure which shows the hole formation by a normal punching tool. It is a figure which shows the hole formation by the worn punching tool. It is a figure which shows the hole formation by the punching tool of an axial shift. It is a block diagram of a hole inspection apparatus. It is a figure which shows the mounting part of a hole inspection apparatus. It is a distribution map of the average hole diameter formed with the punching tool immediately after maintenance and with wear.

  Hereinafter, a green sheet with a carrier film in which a large number of holes are formed by a punching apparatus using a punching pin will be described as an example. FIG. 1 shows an outline of the quality judgment flow of holes formed in a green sheet. The feature of the present invention is to measure the hole feature amount for each formed hole and judge the quality of the hole based on this. There is in point to do.

First, the drilling apparatus 1 will be described with reference to FIG.
N punch pins P (P ₁ , P ₂ ,..., P _N ) are attached to the upper die 2 at a predetermined pitch, and the lower die 3 has a punch pin attached to the upper die 2. Corresponding to P, die holes D (D ₁ , D ₂ ,..., D _N ) in which the punching pins P are inserted when the upper mold 2 is lowered are provided. The green sheet 4 is held on the XY moving means 6 and can move on the lower mold 3, and the upper mold 2 descends in synchronization with the green sheet 4 being positioned at a predetermined position. N holes are drilled in 4 at the same time. The punching area handled by one punching pin can be determined by the punching pin mounting pitch, and is usually in the range of one to several laminated parts. That is, a single punching pin is used to drill as many holes as necessary for one to several laminated parts. FIG. 3 shows a state in which a hole for one laminated part is made with one punching pin, and an area S _{1 for} one laminated part with a punching pin P ₁ (P ₂ , P ₃ ,..., P _N ). This represents that n holes (16 holes in FIG. 3) are drilled in (S ₂ , S ₃ ,..., S _N ). The position and number of holes can be controlled by moving the green sheet 4 in the XY direction.

  FIG. 4 shows a punched portion in a normal state. As shown in FIG. 4 (a), the green sheet 4 with the carrier film 5 is positioned on the lower mold 3, and as shown in FIG. 4 (b). Drilling is performed when the punch pin P is lowered. Although the hole processing may be performed on the green sheet 4 peeled from the carrier film 5, a thin green sheet of about 50 μm is often punched together with the carrier film 5 as shown in FIG. When there is no wear at the tip of the punching pin P or at the entrance of the die hole D, and there is no deviation in the shaft center, a normal hole 10 having a sharp edge as shown in FIG. 4C is formed. FIG. 4C is a schematic view of the upper edge of the normal hole 10 as viewed from above, and the lower figure is a cross-sectional view thereof.

  As the number of drilling operations increases, the tip of the punching tool such as the punching pin P and the die hole D is worn by contact with the ceramic particles of the green sheet 4 and the carrier film 5 holding the green sheet 4. . As shown in FIG. 5 (a), when the tip of the punching tool is rounded due to wear or the like, the sharpness is deteriorated and a good gap is widened for shearing, as shown in FIG. 5 (b). The incomplete hole 11 having the burr 12 around is easily formed. Further, even when the punching tool is not worn, the attachment position of the punching tool is bad, and as shown in FIG. 6 (a), if the axis between the punching pin P and the die hole D is misaligned, As shown in FIG. 6B, an incomplete hole 11 in which the burr 12 remains on one side of the edge is formed. Since the incomplete hole 11 having the burr 12 protrudes from the opening and the area of the opening becomes narrow, the conductor cannot be smoothly embedded in the hole, and a conduction failure between the conductor patterns tends to occur. Thus, when the burr | flash 12 generate | occur | produces, it is desirable to detect generation | occurrence | production of the burr | flash 12 at an early stage, and to perform maintenance, such as a maintenance inspection of a punching tool.

Next, a hole inspection apparatus 20 that quantitatively evaluates holes will be described with reference to FIG.
A placement unit 21 on which the punched green sheet 4 is positioned and set, an image capturing means 22 such as a video camera or a line sensor camera disposed above the placement unit 21, and the placement unit 21 are arranged as X An XY stage 23 capable of positioning control in the -Y direction, a stage control unit 24 for controlling the XY stage 23, an image processing unit 25 for processing image information from the image capturing means 22, an image processing unit 25, and a stage A result determination unit 26 electrically connected to the control unit 24 is provided.

  FIG. 8 shows the placement unit 21. The mounting portion 21 is provided with a light emitting portion 21b below a diffusion plate 21a on which the green sheet 4 is placed. Although the light emission part 21b can be comprised using many light emitting diodes and optical fibers, if it can illuminate from the downward direction of the green sheet 4, it will not specifically limit. Since the light emitted from the mounting portion 21 passes through the through hole formed in the green sheet 4, the image capturing unit 22 can receive the transmitted light and clearly image the opening, and the image processing unit 25 can open the opening. The area and average diameter of the part can be measured as the hole feature amount. The stage control unit 24 stores position information of all the parts where the holes of the green sheet 4 are to be formed or set parts. Accordingly, the measured hole feature amount and its position information are stored as hole information by the result determination unit 26.

Next, the hole quality determination will be described.
The XY stage 23 is moved, a predetermined hole portion on the green sheet 4 is imaged by the image imaging means 22, and the hole feature amount is measured. If a hole is not formed at a predetermined position or the hole is almost closed, the opening area or average diameter is calculated to be zero or almost zero. If there is a burr facing inward, the size of the projected area is calculated. Accordingly, since the opening area or the average diameter is calculated to be small, the hole feature amount can be calculated quantitatively. When the calculation of the hole feature amount of all the hole portions to be measured is completed, the number of holes having a predetermined hole feature amount and the generation position thereof are determined from the hole information based on the logic stored in the result determination unit 26 in advance. Processing is performed to determine the degree of wear of the entire punching tool, to determine wear of each punching pin and sudden damage, and to extract defective holes that may cause product defects.

  Hereinafter, an example of main logic for determining the hole quality will be described with reference to FIGS. The hole feature amount uses an average hole diameter. FIG. 9 is an example showing the distribution of the number of generated average hole diameters measured for all the holes formed in one green sheet when drilling using a punching pin having a diameter of 200 μm. (A) is immediately after exchanging the punching tool, and FIG. 9 (b) is after 1.8 million punches.

(1) Wear determination of the entire punching tool 1) For the target green sheet, the hole feature amount of all holes to be measured is obtained, and the generated number distribution of average hole diameters as shown in FIG. 9 is obtained.
2) The number of holes whose average hole diameter is smaller than the threshold value 1 (for example, 100 μm) set for wear determination is determined as an incomplete hole, the number thereof is determined, and the ratio to the total number of measured holes is determined and calculated as the incomplete hole occurrence rate.
3) When the incomplete hole occurrence rate is smaller than the determination value α (for example, 1%), it is determined that the continuous use is still possible. It should be noted that the incomplete hole information may be used as a record because it can be used when product quality control or history data for hole forming tool maintenance inspection is required.
4) If the incomplete hole occurrence rate is greater than or equal to the determination value α, it is determined that the punching pin or die hole has reached the wear limit, the hole information of the incomplete hole is recorded, and a maintenance inspection command for the punching tool is issued. .
It should be noted that whether the punch pin side or the die hole side should be mainly checked can be classified by the number of occurrences at which the incomplete hole occurrence rate is equal to or higher than the determination value α. That is, if the number of occurrences is smaller than a predetermined number M (for example, 3 times), it is assumed that the punching pin side is worn, and if the number of occurrences exceeds the predetermined number M, the die hole side is also worn. Also, when the punching tool is replaced or reassembled, if there is an assembly failure such as a misalignment of the shaft center, the incomplete hole occurrence rate will continue to increase at an early stage after resuming operation. it can.

(2) Judgment of wear and sudden damage for each punching pin The present invention can be applied to a case of a split mounting structure in which one or a plurality of punching pins can be replaced together.
1) For the target green sheet, the hole feature amount of all holes to be measured is obtained, and the generated number distribution of average hole diameters as shown in FIG. 9 is obtained.
2) For incomplete holes whose average hole diameter is smaller than the threshold value 1 set for wear determination or the threshold value 1 ′ set separately, hole information is recorded and determined in advance from the split mounting structure. The number of incomplete holes formed for each drilling area is obtained and compared to determine whether it is equal to or greater than a predetermined number.
3) For a drilled area where the number of incomplete holes is a predetermined number or more, it is determined that the corresponding punching pin is worn or damaged, and a maintenance inspection command is issued.

(3) Extraction of defective holes 1) For the target green sheet, the hole feature amount of all the measurement target holes is obtained, and the generated number distribution of average hole diameters as shown in FIG. 9 is obtained.
2) A hole having an average hole diameter smaller than the defective hole determination threshold 2 (for example, 40 μm) is defined as a defective hole, the number and occurrence position thereof are calculated, the number of product defects is calculated, and the hole information is recorded as a record. Determine that there is a defective hole in the green sheet.
3) The determination signal and the hole information are output to the outside. Since the laminated parts in the area where the defective holes exist are almost defective products, it is preferable to output in a mapping form in which the location where the defects are generated can be easily identified in a later process.
The occurrence of defective holes is mostly due to breakage of the punching pin, but even when normal holes are punched, the punched member adheres to the tip of the punching pin or is attracted by static electricity. It may occur by entering the through hole and blocking the opening. However, while the former occurs continuously at a fixed point, the latter is weak in regularity, so it can be distinguished based on the hole information, and a maintenance inspection command with this point added can be issued. it can.

  Of the maintenance inspection commands based on the above logics, it is desirable to immediately check the punching pin or lower die for adjustment and replacement for the maintenance inspection command from the overall wear determination of the punching tool. However, the maintenance / inspection command from another may be appropriately added with a determination condition according to the target product. In other words, when a large number of products are formed on a single green sheet, such as a small multilayer electronic component, the product yield decreases due to defective holes, and the operating rate by stopping production equipment such as drilling machines. This is because it is more reasonable to perform maintenance of the device by comparing the profit and loss account with the decline.

  Although three types of hole quality determination methods have been described above, these can be used in combination, or can be determined based on other logic. In other words, the above description has been made with respect to hole formation using a punching pin, but the present invention can be applied even when the hole is formed by other means such as a laser. At this time, it is the same that the hole information is obtained and stored in the result determination unit. However, if the hole forming means is different, the cause and the state of occurrence of the failure are different. Therefore, the logic considering the characteristics of the hole forming means is used. For example, in the case of a laser, there is a great feature that all holes are sequentially formed with a laser beam irradiated from one place. Therefore, instead of obtaining the incomplete hole occurrence rate, the occurrence continuity of holes with the same hole feature amount is obtained. It is preferable to use quality judgment logic that checks whether or not the laser oscillator is defective.

DESCRIPTION OF SYMBOLS 1 Hole processing apparatus 2 Upper die 3 Lower die 6 XY movement table 4 Green sheet 5 Carrier film 10 Normal through hole 11 Incomplete through hole 12 Burr 20 Hole inspection device 21 Mounting table 22 Imaging device 25 Image processing unit 24 Stage control part 26 Result judgment part D Die hole P Punching pin S Product area

Claims (2)

  It is necessary to determine the hole feature amount of the opening for each part where a through hole should be formed by laser processing by image processing, and to maintain and inspect the laser processing equipment based on the continuity of holes with the same hole feature amount A through-hole quality judging method characterized by judging whether or not.   The hole feature is the area or average diameter of the opening, and it is determined whether maintenance inspection of the through-hole forming tool is necessary based on the continuity of the through-hole where the hole feature is below a predetermined threshold. Item 2. The through hole quality judgment method according to Item 1.

Images