JP2010123772A - Position recognition mark of printed wiring board, and method of manufacturing the printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a printed wiring board which does not cause such trouble that a hole having been worked is repeatedly worked even in the case of human error occurrence etc. <P>SOLUTION: In laser hole boring work of a conducting hole for interlayer connection in a build-up type multilayer printed wiring board, a working confirmation mark is provided to the end of a position recognition mark to eliminate such trouble that the hole having been worked is repeatedly worked by mistake even when the hole is a small-diameter hole which can not be determined to have been bored. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a printed wiring board for mounting surface-mounted components, particularly electronic components such as bare chips.

  Due to recent demands for higher functionality, smaller size, and lighter electronic devices such as information terminals and communication terminals, high integration and high speed technologies for semiconductors are rapidly progressing.

  For this reason, products capable of high-density wiring and high-density mounting are also demanded for printed wiring boards on which electronic components such as bare chips for achieving miniaturization and weight reduction are mounted.

  In order to enable high-density wiring and high-density mounting, printed wiring boards are required to reduce the wiring layer line width and line-to-line width, and also to make smaller via hole diameters for via holes used for connection between wiring layers. Yes. As a printed wiring board satisfying these requirements, a multilayer printed wiring board using a build-up method has been put into practical use and is widely used.

  An example of a method for manufacturing a build-up type printed wiring board is shown in FIGS.

  First, the inner layer substrate 20 is manufactured using a copper-clad laminate in which copper foil is bonded to both sides of a glass epoxy substrate, for example, on the base material. After drilling, a copper clad laminate is used in which the conductive paste 22 is filled and the copper foils on the front and back sides are conductively connected.

  An inner layer substrate 20 having a wiring pattern 23 formed on both sides of the copper-clad laminate by a photo process and etching is prepared {see FIG. 5A}.

  Next, the insulating base material 24 and the copper foil 25 are laminated on the front and back surfaces of the inner layer substrate 20 and heated and pressurized with a vacuum hot press machine to produce a four-layer substrate 21 (see FIG. 5B).

  Next, an opening 26 is formed at a predetermined position of the front and back copper foils 25 by a photo process and etching so that the insulating base material 24 is exposed {see FIG. 5 (c)}.

  Next, the copper foil 25 provided with the opening 26 is used as a conformal mask to irradiate a laser to form a hole 27 for an interlayer connection via hole {see FIG. 5 (d)}. Since the insulating resin residue may adhere to the upper surface of the inner wiring pattern 23 that becomes the bottom surface of the hole 27 after laser drilling, the inside of the hole can be cleaned with chemicals such as potassium permanganate. desirable.

  Next, in order to establish an interlayer connection between the inner layer wiring pattern 23 and the outer layer copper foil 25, a copper plating layer is formed.

  First, the electroless copper plating layer 28 is formed on the entire front and back surfaces of the four-layer substrate 21 and the inner surface of the via hole 27 to impart conductivity {see FIG. 5 (e)}. Then, an electrolytic copper plating layer 29 is formed on the electroless copper plating layer 28 {see FIG. 5 (f)}.

  Next, an etching resist 30 is formed on the front and back surfaces of the four-layered substrate 21 connected between the layers by a photo process {see FIG. 6G}.

  Next, an unnecessary copper layer is removed with an etching solution such as cupric chloride to form a via hole 31 and an outer wiring pattern 32, and then the etching resist 30 is peeled off with a solution of sodium hydroxide or the like {FIG. h) See}.

  Thereafter, if necessary, the solder resist 33 may be applied leaving the component mounting portion on the surface of the four-layer board 31 {see FIG. 6 (i)}.

  Finally, as a finishing process, a gold plating process or a water-soluble heat-resistant preflux process is performed for the purpose of rust-proofing copper exposed portions such as lands that serve as connection electrodes during component mounting.

  FIG. 6 (j) shows a gold plating process. First, an electroless nickel plating layer 34 is formed on the exposed copper portion, and an electroless gold plating layer 35 is formed thereon to obtain a four-layer printed wiring board. Can do.

As prior art document information related to the invention of this application, for example, Patent Document 1 is known.
Japanese Patent Laid-Open No. 11-298146

  In the printed wiring board manufacturing process described with reference to FIGS. 5C and 5D, the hole 27 is drilled by the laser processing machine after the opening 26 is formed. The hole diameter is usually formed around 100 μm.

  For this reason, it is not possible to determine with the naked eye whether the substrate is after drilling or before drilling by just looking at the substrate.

  In addition, carbon dioxide lasers are often used for drilling, but YAG lasers and excimer lasers that are capable of drilling with smaller diameters are also being investigated. It has become difficult to determine with the naked eye whether it is the previous substrate.

  At the manufacturing site, it is difficult to confirm the completion of drilling with the naked eye, so if there is a substrate after completion of drilling near the input side of the laser processing machine, the substrate after completion of drilling is mistakenly lasered. There was also a case where an artificial defect that the machine was put into the processing machine and then processed again occurred.

  In addition, when an abnormality or the like of equipment occurs during the hole machining, the laser beam machine is usually temporarily stopped to remove the cause of the abnormality, and then the hole machining is resumed. In this case, there is a possibility that the hole that has been drilled is processed in duplicate.

  Specifically, when 15 sheets of products are made on a single substrate, the equipment was stopped during processing of the 12th sheet. Therefore, after inspection and adjustment, when processing is resumed, processing starts from the 13th sheet. Although it should be done, since it processed from the 11th sheet accidentally, the case where the same hole is processed twice corresponds.

  That is, since the substrate {see FIG. 5 (c)} in which the opening 26 is formed is almost entirely covered with the copper foil 25 except for the opening 26, how many sheets the hole processing has been completed. It is difficult to discriminate with the naked eye. Therefore, it is considered that the above-described problems occur due to artifacts.

  When such a defect occurs, the hole bottom of the hole processed in duplicate receives more impact by laser processing, and as a result, a pin hole 36 is generated in the copper foil which is the wiring pattern 23 on the hole bottom. {See Fig. 7 (a)}.

  Even if the copper plating is performed in the presence of the pinhole 36, the bottom of the hole is completely covered with the copper plating layer, and the pinhole is rarely lost. As shown in FIG. There are many cases where 36 remains.

  Further, since electrical continuity is provided even in the state where the pinhole 36 is generated, it is not determined as a disconnection failure in the electrical inspection process of the printed wiring board, and further, in the appearance inspection process of the printed wiring board. However, since it is difficult to detect pinholes at the bottom of small-diameter holes with current equipment, there is a possibility that they will be used as electronic equipment after being shipped as a good circuit board. It was.

  When the electronic component 37 is mounted on the printed wiring board in which the pinhole 36 is generated, gas is generated from the conductive paste or base material directly under the pinhole 36 through the pinhole 36 to join the mounting electronic component and the printed wiring board. In some cases, voids 39 are generated in the solder 38 that is to be removed.

  Compared with the state in which the electronic component 37 is mounted on a normal printed wiring board {FIG. 8 (a)}, when the void 39 is generated in a relatively large form, as shown in FIG. 8 (b). In addition, a short circuit (short) 40 occurs between adjacent solder joints, and the presence of voids 39 in the solder 38 reduces the bonding strength between the electronic component for mounting and the printed wiring board, and decreases the connection reliability. There was also a possibility that the problem of bringing about.

  The present invention solves the above-described problems, and provides a method for manufacturing a printed wiring board that does not cause a problem of duplicating processed holes even if a human error or equipment abnormality occurs. The purpose is to do.

  In order to solve the above problems, the present invention is formed by removing the copper foil of a multilayer copper clad laminate in which an inner substrate having a wiring pattern, an insulating base material, and an outermost copper foil are laminated. A position recognition mark and an opening, and an interlayer connection hole formed by laser processing on the insulating base material exposed to the opening, and a processing confirmation mark is formed at an end of the position recognition mark. The printed wiring board manufacturing method of the printed wiring board employed by the present invention is to use an insulating base material on both sides of the inner layer substrate having the wiring pattern and copper foil on the outermost layer. Laminating and heating and pressing to form a multilayer copper clad laminate, removing a portion of the copper foil of the copper clad laminate to form a position recognition mark and an opening, and the position recognition mark Image recognition and determination A step of forming a processing confirmation mark at an end of the position recognition mark; and a step of forming a hole for interlayer connection in the insulating base material exposed from the opening with the position recognition mark as a reference. The step of recognizing and determining the image is a step of confirming that the processing confirmation mark does not exist.

  Specifically, when drilling with a laser processing machine, the position recognition mark provided on the surface of the substrate for laser beam alignment is recognized by the CCD camera immediately after the position recognition mark is recognized by the laser. A program for turning is added to the laser processing data. As a result, processing confirmation marks are formed on the position recognition marks provided at least at the four corners of the processed sheet. By setting such position recognition marks so that the CCD camera cannot recognize them, overlapping processing is performed. Can be prevented.

  By using the printed wiring board position recognition mark and printed wiring board manufacturing method of the present invention, drilling has been completed in laser drilling of conductive holes (via holes) for interlayer connection on high-density boards and bare chip mounting boards. Thus, it is possible to solve the problem of overlapping machining with respect to a machined hole that has occurred when drilling a small-diameter hole that cannot be determined.

  As a result, it is possible to solve the above-described conventional problems and form a highly reliable conductive hole for interlayer connection, and stably mount components on the printed wiring board.

  Embodiments of the present invention will be described below with reference to the drawings.

  First, FIG. 1 shows a conformal mask in laser processing of position recognition marks 2 and interlayer connection holes in at least four corners of a multilayer substrate 1 in which an insulating base material and copper foil are laminated on the front and back of an inner layer substrate and molded by vacuum hot pressing. 1 is a plan view showing a structure in which an opening 3 is formed. The manufacturing method is as follows.

  First, an inner layer substrate 5 having wiring patterns 4 formed on both sides is prepared {see FIG. 2 (a)}.

  Next, an insulating base material 6 such as a B-stage prepreg is laminated on both the front and back surfaces of the inner layer substrate 5 and a copper foil 7 is laminated on the outermost layer, and heated and pressed with a vacuum hot press machine to form a multilayer copper clad having a four layer structure A laminated substrate is produced {see FIG. 2B}. In addition, in order to realize high wiring accommodation, it is possible to use a multilayer substrate in which layers are connected by a conduction hole filled with a conductive paste. This will be described using the inner layer substrate.

  Next, the opening 3 is formed at a predetermined position of the copper foil 7 on the front and back sides of the copper clad laminated substrate so that the insulating base 6 is exposed by a photo process and etching, and the position recognition mark 2 is simultaneously formed { 2 (c)}. The opening shape and size of the position recognition mark 2 are not particularly limited as long as they can be recognized by a CCD camera of a laser processing machine (for example, Φ1.0 mm). The opening 3 is preferably formed immediately above the wiring pattern 4 of the inner layer substrate 5. As a result, the interlayer connection between the surface layer and the inner layer substrate can be achieved by the presence of the wiring pattern 4 of the inner layer substrate 5 at the bottom of the hole for interlayer connection described later.

  Next, the position recognition marks 2 at the four corners of the multilayer substrate 1 are image-recognized and detected by a CCD camera (not shown) of the laser processing machine, and the expansion and contraction of the substrate and the occurrence of distortion are determined from the distance between the plurality of position recognition marks. The state is detected and corrected by multiplying by a dimensional correction coefficient (scale factor) according to the contraction and distortion of the substrate as necessary.

  The step of recognizing the position recognition mark 2 detects only the position recognition mark 2 in the image recognition area, and confirms that a processing confirmation mark (details shown in FIG. 3) described later does not exist. It is a process to do.

  Confirming the presence / absence of the processing confirmation mark includes determining whether or not the next step can be performed, and the step of recognizing and determining the position recognition mark 2 is a characteristic of the present invention. One of the configurations.

  Next, after confirming that the aforementioned processing confirmation mark does not exist, a processing confirmation mark 9 is formed at the end of the position recognition mark 2 as shown in FIG. The laser beam is moved directly above the opening 3 provided at the position, and the laser is irradiated to form an interlayer connection hole 8. This step is performed for each of the front and back surfaces, and holes 8 are formed on both the front and back surfaces.

  Thereafter, a multilayer printed wiring board is obtained through the same processes as those shown in FIG. 6 from the conventional FIG.

  As shown in the printed wiring board manufacturing method of the present invention, when the interlayer connection hole 8 is formed, the processing confirmation mark 9 is inevitably formed at the end of the position recognition mark 2. It becomes.

  The position recognition mark of the printed wiring board of the present invention is that the processing confirmation mark 9 is formed at the end of the position recognition mark.

  The position recognition mark is image-recognized, the presence / absence of the processing confirmation mark 9 is confirmed, and whether or not the next process can be executed is determined. If the presence of the processing confirmation mark 9 is confirmed, By not processing the connection hole, the conventional problem can be solved.

  That is, the laser processing to the insulating base 6 exposed in the opening 3 formed immediately above the wiring pattern 4 of the inner layer substrate 5 forms a hole 8 and also irradiates the wiring pattern 4 of the inner layer substrate 5 with laser light. However, by adopting the printed wiring board position recognition mark and the manufacturing method of the present invention, laser beam irradiation is not performed redundantly, and a pinhole is generated in the wiring pattern 4 of the inner layer substrate 5. There is nothing.

  It is effective to increase the number of position recognition marks in order to further improve the drilling position accuracy.

  In the example of FIG. 1, a case where a single multilayer substrate 1 is composed of a plurality of individual multilayer substrates 1a, specifically, the individual multilayer substrate 1a is a multi-chamfering composed of 15 sheets. By providing the position recognition marks 2a at the four corners of each individual multi-layer substrate 1a, it becomes possible to make holes at more accurate positions.

  The arrows shown in FIG. 1 indicate the order of laser drilling, and laser drilling is performed for each individual multilayer board 1a from the upper right end to the upper left end, from the middle right end to the middle left end, and from the lower right end to the lower left end. It shows that it will be broken.

  Even in such a multi-chamfer configuration, the process of recognizing and determining the position recognition mark as described above is performed for each individual multilayer substrate, and whether or not the next process can be performed is determined based on the presence or absence of the processing confirmation mark. By doing so, it is possible to prevent duplicated hole processing.

  In the case shown in FIG. 1, when laser drilling is performed on the individual multilayer substrate 1a on the first sheet (upper right corner of the drawing), the position recognition marks 2a to 2d as position recognition marks are sequentially placed on a CCD camera (not shown). ), Positioning is performed, and a laser beam is moved to a predetermined position after being subjected to a dimensional correction coefficient (scale factor) corresponding to the contraction and distortion of the substrate to make a hole.

  In this step, immediately after the position recognition mark 2a is detected by the CCD camera and positioned, the copper foil at the end of the position recognition mark is irradiated with the laser a plurality of times, as shown in FIG. After the processing confirmation mark 9 is given to the mark, a laser is irradiated to the opening 3 provided in the conformal mask, which is the position that should be originally drilled, to make a hole for interlayer connection.

  That is, by adding data to be processed a plurality of times to the copper-plated portion at the end of the position recognition mark 2a to the drilling data of the laser processing machine, the position recognition mark 2a of the individual multilayer substrate 1a once drilled is added. The processing confirmation mark 9 is present at the end.

  Specifically, in the image recognition area (dotted line) of the CCD camera, when only the shape of the position recognition mark 2a is recognized as shown in FIG. 4A, an operation of irradiating the opening 3 with laser is performed. If the processing confirmation mark 9 as shown in FIG. 4B is present so that a recognition error occurs, the individual multilayer substrate or the multilayer substrate that has been subjected to the drilling processing is not processed repeatedly.

  Note that setting so as to cause a recognition error includes a case where the center point of the position recognition mark 2a cannot be correctly recognized, and the setting is relatively easy.

  The processing confirmation mark can be formed in a dot shape on the copper foil 7 at a location different from the end of the position recognition mark 2a. The laser processing energy can be reduced and formed easily, and the image recognition area of the CCD camera can be made the same as that of the position recognition mark 2a. This is also a desirable form in terms of operating efficiency.

  In particular, it is desirable not to make a hole in the insulating base material by irradiating a laser to a position where the exposed portion of the position recognition mark 2a is not exposed to the exposed insulating base material and irradiating a laser with a laser. . Thereby, image recognition can be stably performed by the CCD camera.

Thus, according to the printed wiring board position recognition mark and the printed wiring board manufacturing method of the present embodiment, the following effects can be obtained.
(1) At the site where printed wiring boards are manufactured, the space around the laser processing machine is narrow, or there are many production processes, and the substrate that has been drilled and the substrate before drilling are messy around the laser processing machine. In the past, there has been a possibility that a substrate that has already been drilled is mistakenly drilled again and damages the bottom of the hole.

However, according to the present invention, even if a substrate that has been drilled is mistakenly set in the laser processing machine and started, a processing confirmation mark exists at the end of the position recognition mark, so the CCD camera The center point of the position recognition mark cannot be correctly recognized, a recognition error is displayed on the operation screen of the laser processing machine, and the equipment stops. Therefore, it does not occur that the holes that have been processed are overlapped.
(2) In order to prevent duplicate processed products from being shipped as non-defective products in the electrical inspection process when the substrate set in the laser processing machine temporarily stops due to equipment malfunction during processing. Such a substrate in the middle of processing was disposed of.

  For example, if the multi-chamfering configuration is made up of 15 sheets of individual multi-layer substrates on one substrate, the equipment stops at the 12th sheet even if the 11th sheet is normally drilled, Since one of the substrates was discarded, all of the 15 individual multi-layer substrates were treated as defective products.

  However, according to the present invention, when removing the abnormality of the laser processing machine and resuming the processing, the processing confirmation mark exists at the end of the position recognition mark even if the processing is erroneously started with the sheet before the 12th. As a result, a recognition error occurs in the CCD camera and the equipment is stopped, so that there is no overlap processing.

  Even if processing is started from the 14th sheet, there are only 2 sheets of defects, the 12th sheet being processed and the 13th sheet not processed. Of course, if the processing is resumed from the 13th sheet, the defect is only one sheet in the 12th sheet being processed. In addition, since the sheet | seat in the middle of a process or an unprocessed sheet | seat does not have the via hole for conduction | electrical_connection, it is removed as a disconnection defect in the electrical inspection of a post process, Therefore It is not shipped as a product.

  From the above, even if the equipment is stopped during processing, duplicate processing due to human error does not occur, and defective products that are discarded are also targeted, and waste can be minimized.

  As described above, according to the present invention, even if a human error or equipment abnormality occurs in the process of manufacturing a printed wiring board such as a high-density board or a bare chip mounting board, a hole that has been drilled is duplicated. Therefore, it is possible to provide a printed wiring board having a highly reliable conduction hole for interlayer connection. Furthermore, since the defects to be discarded can be minimized, the industrial applicability of the present invention can be said to be great.

The top view of the board | substrate in 1 process of the manufacturing method of the printed wiring board in embodiment of this invention Process sectional drawing which shows the manufacturing method of the printed wiring board in the embodiment Detailed view of printed circuit board position recognition mark in the same embodiment The figure which shows 1 process of the manufacturing method of the printed wiring board in the embodiment Process sectional drawing which shows the manufacturing method of the conventional printed wiring board Process sectional drawing which shows the manufacturing method of the conventional printed wiring board Sectional drawing which shows the subject in the manufacturing method of the conventional printed wiring board Sectional view showing problems in mounting components on a conventional printed wiring board

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Multilayer substrate 1a Individual multilayer substrate 2, 2a-2d Position recognition mark 3 Opening part 4 Wiring pattern 5 Inner layer substrate 6 Insulation base material 7 Copper foil 8 Hole 9 Processing confirmation mark

Claims (13)

A position recognition mark and an opening formed by removing the copper foil of a multilayer copper clad laminate in which an inner layer substrate having a wiring pattern, an insulating base material, and an outermost copper foil are laminated;
A hole for interlayer connection formed by laser processing on the insulating base exposed in the opening,
A position recognition mark for a printed wiring board, wherein a processing confirmation mark is formed at an end of the position recognition mark. 2. The position recognition mark for a printed wiring board according to claim 1, wherein the processing confirmation mark is formed immediately before forming the hole for interlayer connection. 2. The printed wiring board position recognition mark according to claim 1, wherein the processing confirmation mark is formed as a defective portion by removing the copper foil at the end of the position recognition mark by laser processing. 2. The position recognition mark for a printed wiring board according to claim 1, wherein a wiring pattern of the inner layer substrate is present at the bottom of the hole for interlayer connection. 2. The position recognition mark for a printed wiring board according to claim 1, wherein the position recognition mark is formed at at least four corners of the copper clad laminate. The multilayer copper-clad laminate is a multi-sided board composed of a plurality of individual multilayer substrates, and position recognition marks are formed in at least four corners of each individual multilayer substrate. The printed wiring board position recognition mark. 2. The printed wiring board position recognition mark according to claim 1, wherein the inner layer substrate is a multilayer substrate having a surface wiring pattern and interlayer conduction means. A process of forming a multilayer copper clad laminate by laminating an insulating base material and copper foil on the outermost layer on both sides of the inner layer substrate having a wiring pattern, and heating and pressing; and
Removing a part of the copper foil of the copper-clad laminate to form a position recognition mark and an opening; and recognizing and determining the position recognition mark;
Forming a processing confirmation mark at an end of the position recognition mark;
Forming a hole for interlayer connection in the insulating substrate exposed from the opening with the position recognition mark as a reference,
The method of manufacturing a printed wiring board, wherein the step of recognizing and determining the position recognition mark is a step of confirming that the processing confirmation mark does not exist. The step of forming a processing confirmation mark at the end of the position recognition mark is a step of removing a part of the copper foil at the end of the position recognition mark by laser processing to form a defective portion. Item 9. A method for producing a printed wiring board according to Item 8. The opening is formed immediately above the wiring pattern of the inner layer substrate, the hole for interlayer connection is formed by laser processing by laser light irradiation, and the laser light is also irradiated on the wiring pattern. Item 9. A method for producing a printed wiring board according to Item 8. 9. The method of manufacturing a printed wiring board according to claim 8, wherein the step of recognizing and determining the position recognition mark includes determining whether or not the subsequent steps can be executed. The multi-layered copper-clad laminate is a multi-sided one composed of a plurality of individual multilayer substrates, each individual multilayer substrate is provided with a position recognition mark,
The method for manufacturing a printed wiring board according to claim 8, wherein the step of recognizing and determining the position recognition mark is performed for each of the individual multilayer boards. 9. The method for manufacturing a printed wiring board according to claim 8, wherein the inner layer substrate is a double-sided or multilayered substrate that is interlayer-connected by a conductive hole filled with a conductive paste.

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