JP3988250B2 - Multilayer circuit board manufacturing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a multilayer circuit board having an improved structure for forming recognition marks such as characters and symbols indicating product part numbers and component alignment marks.
[0002]
[Problems to be solved by the invention]
In the case of a multilayer circuit board, for example, an alumina laminated board for hybrid IC, a conductor pattern including an electrode to which a surface mount component is connected is formed on the surface, and characters, symbols and parts indicating the product part number are formed. Generally, a recognition mark such as an alignment mark is formed. The conductor pattern and the recognition mark are formed simultaneously by printing a conductor paste on the surface of the alumina laminated substrate by screen printing or the like and baking it.
[0003]
FIG. 5 shows an example of such a recognition mark. Here, a conductor pattern 2 is formed on the surface portion of the alumina laminated substrate 1, and a part of the conductor pattern 2 constitutes electrodes 3 and 4 for component mounting. Then, in a so-called blank portion (the ground portion of the substrate 1) between the conductor patterns 2 and 2 shown on the left side in FIG. 5, a mark 5 made up of the characters “2A” indicating the product number of the product is formed. Yes. Further, in the vicinity of the electrode 3 shown in the center in FIG. 5, a triangular mark 6 indicating the mounting direction of the directional component is formed. Further, in the vicinity of the electrode 4 shown on the right side in FIG. 5, circular marks 7 for positioning components (for example, flip-chip type IC bare chip) are located at two diagonal positions. 7 is formed.
[0004]
By the way, since the mark 5 as described above has conductivity, it cannot be formed in the vicinity of the conductor patterns 2 and 2, and for this reason, a certain amount of space is formed between the conductor patterns 2 and 2 and the mark 5. An interval must be provided, and a relatively large blank portion is required between the conductor patterns 2 and 2. Further, for the conductors 3 and 4, in order to ensure the flatness of the component mounting position on the substrate 1, and to prevent the deterioration of the cleaning property and the resin injection property at the time of resin potting, etc. The marks 6 and 7 must be provided slightly outside.
[0005]
As described above, in order to form the recognition marks 5 to 7, the conventional one requires a corresponding area on the surface portion of the substrate 1, and is originally a multilayer structure for miniaturizing the substrate 1. Nevertheless, the formation of the marks 5 to 7 has been an obstacle to miniaturization of the substrate 1.
[0006]
The present invention has been made in view of the above circumstances, and an object thereof is to provide a recognition mark, which can reduce the area required to form the mark and can be miniaturized. It is in providing the manufacturing method of a board | substrate.
[0007]
[Means for Solving the Problems]
Conventionally, it has been common knowledge that a recognition mark formed on a substrate is provided on the surface of the substrate so that a human can visually recognize or recognize it with an optical camera. However, the present inventor has confirmed that even if a recognition mark is formed on the inner layer portion of the multilayer circuit board, recognition by humans or recognition using a device is possible without being bound by such common sense. The present invention has been accomplished.
[0008]
That is, the method for manufacturing a multilayer circuit board according to the present invention has a multilayer insulating base material layer made of a ceramic material, has a conductor pattern on the surface and an inner layer thereof, and has a mark for recognizing a surface-mounted component. A multilayer circuit board is manufactured which is an inner layer portion corresponding to a portion of the base material layer where the surface conductor pattern is not formed and is provided at a position corresponding to the inner side of the component connection electrode in the surface conductor pattern. A method of forming a pattern to be the surface conductor pattern and the inner layer conductor pattern on a plurality of equivalent green sheets as materials of the insulating base layers, and the green sheet a step of the inner layer conductor pattern and the same layer as a position on the marked made to pattern the inner layer conductor pattern to become should pattern integrally formed of It characterized in place comprising the steps of a laminate obtained by integrating pressurized by stacking green sheets of the plurality of layers min, and a step of firing the laminate (the invention of claim 1).
[0009]
Here, even if there is a recognition mark on the inner layer, the characters and symbols indicating the product number etc. of the mark need only be visible through the human eye from the surface, that is, it can be seen through transparently. The mark indicating the mounting direction and mounting position can be recognized by an optical camera if it is thin and transparent, or even if it is optically unrecognizable, it can be recognized by using an X-ray transmission device. It becomes possible. At this time, when the mark is provided on the inner layer portion, it is not necessary to provide a space between the surface conductor pattern and the mark on the inner layer portion in a plan view, and the mark is located inside the component mounting position. It does not matter if it is located.
[0010]
Therefore, according to the first aspect of the present invention, a large area for forming a mark is not necessary between the surface conductor patterns on the surface portion, and an area for providing a mark outside the electrode is not necessary. It is possible to reduce the area of the required surface portion and to achieve an excellent effect that the overall size can be reduced.
[0011]
The present invention can be applied to a ceramic laminated substrate in which the insulating base is made of a ceramic material . In this case, a multilayer circuit board can be obtained by using the same green sheets for a plurality of equivalent layers as a material, laminating, pressing, and firing. Since one insulating base layer of this type of ceramic laminated substrate is very thin, even if a mark is provided on the inner layer portion, it can be seen through by a human or an optical camera, and even if the insulating base layer is thick, X Recognition is possible by using a line transmission device.
[0012]
Also, the mark is a can be formed by printing or the like on the surface of the insulating base layer used for forming the inner layer of the stage before lamination, this time, by forming a mark integrally with the inner layer conductor pattern The mark forming process can be executed simultaneously with the inner layer conductor pattern forming process, and the process can be simplified as compared with the case where the mark forming process is performed separately.
[0013]
As described above, the mark is formed so as to be seen through by an optical camera or human eyes (invention of claim 2 ), or formed so as to be recognized by an X-ray transmission device (claim). 3 ), and any one of these structures can achieve the intended purpose.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to an alumina laminated substrate will be described with reference to FIGS. 1 and 2 schematically show a schematic configuration of an alumina laminated substrate 11 as a multilayer circuit board according to the present embodiment by picking up only a main part. This alumina laminated substrate 11 has a multilayer structure, that is, three insulating base material layers 12, 13, and 14 in this case. Each of these insulating base layers 12, 13, 14 is made of a ceramic material, in this case alumina. When these insulating base layers are distinguished, they are referred to as a first insulating base layer 12, a second insulating base layer 13, and a third insulating base layer 14 in order from the top.
[0015]
A surface conductor pattern 15 made of a refractory metal material such as tungsten or molybdenum is provided on the surface of the alumina laminated substrate 11 (the upper surface of the first insulating base material layer 12). An electrode 16 for connecting chip components and an electrode 17 for connecting a flip-chip type semiconductor bare chip are configured. In this case, a pair of chip component connection electrodes 16 are arranged at intervals in the front-rear direction, and a plurality of semiconductor bare chip connection electrodes 17 are arranged in a square.
[0016]
As shown only in FIG. 3E, inner layer conductor patterns 18 and 19 made of a refractory metal material such as tungsten or molybdenum are provided on the inner layer of the alumina laminated substrate 11. Among these, the inner layer conductor pattern 18 is formed between the first insulating substrate layer 12 and the second insulating substrate layer 13, and the inner layer conductor pattern 19 includes the second insulating substrate layer 13 and the third insulating substrate layer 13. 14. The surface conductor pattern 15 and the inner layer conductor patterns 18 and 19 are connected by through holes 20 at important points. The through hole 20 is also filled with a refractory metal material such as tungsten or molybdenum.
[0017]
Although not shown, the surface conductor pattern 15 (electrodes 16 and 17) is plated with silver or copper as necessary. On the alumina laminated substrate 11, a required film circuit element such as a thick film resistor is formed so as to be connected to the electrodes 16, 17 and the like, and a required chip is formed. Surface mount components such as components and semiconductor bare chip components are mounted. Further, resin potting is performed on the gap portion (around the bump) between the lower surface of the semiconductor bare chip and the upper surface of the alumina laminated substrate 11 for protection.
[0018]
Now, recognition marks 21, 22, and 23 are provided on the inner layer portion of the alumina laminated substrate 11. As shown in FIGS. 2 and 3, these marks 21, 22, and 23 are formed between the first insulating base layer 12 and the second insulating base layer 13, that is, in the same layer as the inner layer conductor pattern 18. The inner layer conductor pattern 18 is made of a high melting point metal material such as tungsten or molybdenum.
[0019]
As shown in FIG. 1, among these marks, the mark 21 shown on the left side in FIG. 1 is composed of the letter “2A” indicating the product number of the product. 15 and 15 are formed in positions adjacent to the surface conductor patterns 15 and 15 in a blank portion. Further, the mark 22 shown in the central part in FIG. 1 is a triangular mark indicating the mounting direction of a directional component, and is located in the middle part of the electrodes 16 and 16 when seen through from above. Is formed.
[0020]
Further, the mark 23 shown on the right side in FIG. 1 is composed of a pair of circular marks for aligning the components, and in a state seen through from the upper surface, the diagonal of the square area inside the electrode 17 It is formed in two places. As will be described later, these marks 21, 22, and 23 are integrally formed with a thickness equivalent to the inner layer conductor pattern 18 (for example, a sheet thickness of 0.25 mm). Of course, the marks 21, 22, and 23 are formed at positions where the inner layer conductor pattern 18 is not formed (positions away from the inner layer conductor pattern 18).
[0021]
Here, the manufacturing method of the above-mentioned alumina laminated substrate 11 will be briefly described with reference to FIG. FIG. 3 schematically shows a manufacturing process of the alumina laminated substrate 11. First, as a material of each insulating base material layer 12, 13, and 14, as shown in FIG. 3A, three known alumina green sheets 24 are used, and as shown in FIG. First, holes 24a to be through holes 20 are formed at required positions of the green sheets 24, and the holes 24a are filled with a refractory metal paste (for example, tungsten paste) 25.
[0022]
Next, as shown in FIG. 3C, a refractory metal paste (tungsten paste) 26 that becomes the conductor patterns 15, 18, and 19 is printed on the surface of each green sheet 24 by, for example, screen printing. At this time, the refractory metal paste 26a to be the marks 21, 22, and 23 is simultaneously printed and applied on the second green sheet 24 from the top (becomes the insulating base layer 13). .
[0023]
Next, as shown in FIG. 3D, the three green sheets 24 are stacked and pressed to form a stacked body in which the three green sheets 24 are integrated. Thereafter, the laminate is baked at 1600 ° C., for example, in a reducing atmosphere, whereby the alumina laminated substrate 11 is obtained as shown in FIG. At this time, the refractory metal paste 26a printed and applied on the second green sheet 24 from the top becomes the marks 21, 22, and 23, and between the first insulating base layer 12 and the second insulating base layer 13 It is formed in a form embedded in the.
[0024]
In the alumina laminated substrate 11 having the above configuration, the mark 21 indicating the product number is formed in the inner layer portion, but as shown in FIG. 1, it can be seen through thinly from the surface. It is possible, and a manufacturing worker etc. can recognize the product number by looking at the mark 21. Similarly, the mark 22 indicating the mounting direction of the component and the mark 23 for alignment are also seen thinly from the surface, and can be recognized by the optical camera.
[0025]
Alternatively, even when the first insulating base material layer 12 is thick and the marks 22 and 23 cannot be recognized by the optical camera, the X-ray transmission device can be used for recognition. FIG. 4 shows a state of recognizing the marks 22 and 23 on the inner layer of the alumina laminated substrate 11 using the X-ray transmission device (X-ray camera 27). X-ray A is irradiated from the side, the image is picked up by the X-ray camera 27 on the upper surface side, and the obtained image data is processed to detect the orientation and position of the marks 22 and 23 formed on the inner layer portion. Is possible.
[0026]
And the area in the surface part of the alumina laminated substrate 11 required by formation of the marks 21, 22, and 23 by providing the marks 21, 22, and 23 in the inner layer part in this way is shown in FIG. It can be made smaller than the conventional one. That is, the mark 5 shown in FIG. 5 needs to be formed at a distance from the conductor patterns 2 and 2, and a relatively large blank portion is required. However, as shown in FIG. Since the mark 21 does not need to be spaced from the surface conductor pattern 15 in a plan view, it is not necessary to provide a large area between the surface conductor patterns 15 and 15.
[0027]
Further, the marks 6 and 7 shown in FIG. 5 are provided on the outside of the component mounting position in order to ensure flatness of the component mounting position on the substrate 1, prevent deterioration of the cleaning property, and ensure resin injection property in resin potting. However, as shown in FIG. 1, the marks 22 and 23 formed on the inner layer do not have any adverse effect on the surface of the alumina laminated substrate 11, so that component mounting is possible. It is possible to form it inside the position, and accordingly, a mark forming region in the outer portion of the electrodes 16 and 17 becomes unnecessary.
[0028]
Therefore, according to the present embodiment, a large area for forming a mark is not necessary between the surface conductor patterns 15 and 15 on the surface portion of the alumina laminated substrate 11, and an area for providing a mark outside the electrodes 16 and 17 is necessary. Therefore, unlike the conventional marks 5 to 7 which obstruct the downsizing of the substrate 1, it is possible to reduce the surface area required for forming the marks 21, 22, and 23. Thus, an excellent practical effect that the overall size can be reduced can be obtained.
[0029]
Further, in particular, in the present embodiment, the marks 21, 22, and 23 are formed at a depth position so that the marks 21, 22, and 23 can be seen through the surface of the alumina laminated substrate 11 thinly. It is possible to see through the eyes, and it becomes more effective. Furthermore, since the marks 21, 22 and 23 are formed integrally with the inner layer conductor pattern 18, the marks 21, 22 and 23 can be formed simultaneously with the inner layer conductor pattern 18 forming process. Compared with the case where the formation process of 22 and 23 is performed separately, the merit that a process can be simplified can also be acquired.
[0030]
In the above embodiment, the marks 21, 22, and 23 are formed on the second layer of the inner layer portion. However, even if the mark is located at a deep position of the third layer or less, another conductor pattern and the stacking direction are used. As long as it is formed at a position that does not overlap with the X-ray transmission device, it can be recognized using an X-ray transmission device. Other, in the range in the above embodiment, a three-layer insulating base layer in order to simplify the description, such is of course that may be 4 or more layers, the present invention without departing from the gist It can be implemented with appropriate modifications.
[Brief description of the drawings]
1 is a schematic plan view of an alumina laminated substrate showing a state where a mark is seen through, showing an embodiment of the present invention. FIG. 2 is a schematic longitudinal front view of the alumina laminated substrate. FIG. 4 is a diagram showing a substrate manufacturing process. FIG. 4 is a diagram schematically showing how a mark is recognized by an X-ray transmission device. FIG. 5 is a diagram showing a conventional example in which a mark is formed on an alumina laminated substrate. Schematic plan view [Explanation of symbols]
In the drawings, 11 is an alumina laminated substrate (multilayer circuit board), 12 to 14 are insulating base layers, 15 is a surface conductor pattern, 16 and 17 are electrodes (surface conductor pattern), 18 and 19 are inner layer conductor patterns, 21 to 21 Reference numeral 23 denotes a mark, and 27 denotes an X-ray camera (X-ray transmission device).

Claims (3)

It has a multilayer insulating base material layer made of a ceramic material, and has a conductor pattern on its surface and inner layer, and the surface conductor pattern is formed in the insulating base material layer with a mark for recognition of surface mount components. A method for manufacturing a multilayer circuit board that is an inner layer portion corresponding to a portion that is not present and is provided at a position corresponding to the inside of an electrode for connection of a corresponding component of the surface conductor pattern ,
A step of forming a pattern to be the surface conductor pattern and the inner layer conductor pattern with respect to the equivalent green sheet for a plurality of layers as the material of each insulating base layer,
Forming the pattern to be the mark integrally with the pattern to be the inner layer conductor pattern at the same layer as the inner layer conductor pattern in the green sheet;
A step of laminating the green sheets for the plurality of layers and applying pressure to form a laminated body; and
And a step of firing the laminated body. 2. The method of manufacturing a multilayer circuit board according to claim 1, wherein the mark is formed so as to be seen through by an optical camera or a human eye . The method for manufacturing a multilayer circuit board according to claim 1 , wherein the mark is formed so as to be recognized by an X-ray transmission device .

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