JP2009283659A - Printed wiring board, method for manufacturing thereof, and multilayer printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed wiring board allowing a resistance value to be easily controlled to a predetermined value, and stably manufacturable with a good yield; and a multilayer printed wiring board. <P>SOLUTION: This printed wiring board 10 is provided with an insulation part 11, and first conductive parts 12 formed on one-side surface 11a of the insulation part 11. The first conductive part 12 may be, for instance, a conductive body (wiring layer) formed in a predetermined pattern. On the one-side surface 11a of the insulation part 11, a second conductive part 13 formed separately from the first conductive parts 12 so as not to directly contact the first conductive parts 12, and third conductive parts 14 electrically connecting the first conductive parts 12 to the second conductive part 13 are formed. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a printed wiring board, and more particularly to a printed wiring board provided with a resistor.

  A printed wiring board in which a conductor wiring or a thin film resistor is formed on an insulator is known in accordance with demands for downsizing, thinning, and high functionality of electronic devices (see, for example, Patent Documents 1 and 2). An example of a conventional multilayer printed wiring board in which a plurality of such printed wiring boards are laminated is shown in FIG. In the multilayer printed wiring board 101, a junction insulating portion 104 is disposed between the two insulating portions 102 and 103. The bonding insulating portion 104 forms an adhesive layer that bonds the insulating portion 102 and the insulating portion 103 together.

  A second conductive portion 105 is formed on one surface of the insulating portion 103. For example, the second conductive portion 105 is a thin film resistor formed by applying a paste-like resistance material. In addition, first conductive portions 107 a and 107 b are formed on both sides of the second conductive portion 105. The first conductive portions 107a and 107b form conductive wiring formed in a predetermined shape (pattern). The second conductive portion 105 covers both ends of the first conductive portions 107a and 107b so that the second conductive portion 105 is electrically connected to the first conductive portions 107a and 107b. A step S rising in the thickness direction is formed.

However, in the conventional multilayer printed wiring board provided with the thin film resistor as described above, it is difficult to form the thin film resistor forming the second conductive portion so as to have a predetermined resistance value, and it can be manufactured stably. There was a problem that it was difficult to do. That is, in order to ensure conduction between the first conductive portions 107a and 107b and the second conductive portion 105, the step S which covers both ends of the second conductive portion 105 with a part of the first conductive portions 107a and 107b, respectively. Therefore, when this second conductive portion 105 is formed by printing or the like, printing unevenness is likely to occur at portions covering the first conductive portions 107a and 107b. For this reason, it becomes difficult to control the resistance value of the thin film resistor constituting the second conductive portion 105, and there are problems such as non-uniform resistance values and deterioration in yield.
JP 2006-222110 A Japanese Patent Laid-Open No. 06-77660

  The present invention has been made in view of the above circumstances, and it is easy to control a resistance value to a predetermined value, and a printed wiring board and a multilayer printed wiring board that can be stably manufactured with a high yield. The purpose is to provide.

  Another object of the present invention is to provide a method of manufacturing a printed wiring board that can be stably manufactured with a high yield by controlling the resistance value of the resistor to a predetermined value.

In the printed wiring board according to claim 1 of the present invention, the insulating portion, the first conductive portion formed on one surface of the insulating portion, and the first conductive portion so as not to be in direct contact with the one surface of the insulating portion. A printed wiring board comprising at least a second conductive part formed at a distance, and a third conductive part for electrically connecting the first conductive part and the second conductive part, wherein the second conductive part Is made of an electric resistor, and the third conductive portion is made of a noble metal.
The printed wiring board according to claim 2 of the present invention is the printed wiring board according to claim 1, wherein the second conductive portion is formed to have the same thickness as or thinner than the first conductive portion. And
A multilayer printed wiring board according to claim 3 of the present invention is a multilayer printed wiring board according to claim 1, in which a plurality of the printed wiring boards according to claim 1 are stacked via a junction insulating part, and the first conductive parts arranged in an overlapping manner are electrically connected. It has the part.
According to a fourth aspect of the present invention, there is provided a printed wiring board manufacturing method comprising: forming a first conductive portion having a predetermined shape on one surface of an insulating portion; and directly contacting the first conductive portion using a resistor paste. At least a step of forming a second conductive portion and a step of forming a third conductive portion that electrically connects the first conductive portion and the second conductive portion using a noble metal paste. It is characterized by that.

  According to the printed wiring board and multilayer printed wiring board of the present invention, the second conductive portion forming the resistor is formed with a constant thickness without a step. As a result, it becomes easy to form a thickness and size having a target resistance value, and it becomes possible to solve problems such as non-uniform resistance values among products and deterioration of yield.

  In addition, since the second conductive portion is connected to the first conductive portion forming the wiring through the third conductive portion made of a noble metal, the resistance value rises above a predetermined value even in a high temperature and high humidity environment. Can be prevented.

  Furthermore, by connecting the second conductive portion via the third conductive portion without directly contacting the first conductive portion forming the wiring, the thickness of the second conductive portion can be reduced without causing a conduction failure. It is possible to make it the same as or thinner than the thickness of the conductive part, realizing a higher resistance value in the same area, and further miniaturization of printed wiring boards equipped with resistors and multilayer printed wiring boards It is possible to reduce the thickness.

  In addition, according to the method for manufacturing a multilayer printed wiring board of the present invention, the second conductive portion forming the resistor can be formed with a constant thickness without a step. Therefore, it can be formed with high accuracy so that the resistance value of the second conductive portion becomes a predetermined (target) value. That is, since the second conductive portion is connected to the first conductive portion through the third conductive portion, the entire second conductive portion can be formed with a constant thickness and no step. For this reason, it becomes easy to form in the thickness and size which have the target resistance value, and it can prevent generation | occurrence | production of the nonuniformity of resistance value between products, the deterioration of a yield, etc.

  In addition, by connecting the second conductive part via the third conductive part without directly contacting the first conductive part, the thickness of the second conductive part can be set to the thickness of the first conductive part without causing poor conduction. It can be made the same or thinner, and a higher resistance value can be realized with the same area, and the printed wiring board can be made smaller and thinner.

  In addition, since the second conductive portion that forms the resistor is formed in a later process than the formation of the first conductive portion, corrosion when the first conductive portion is formed by etching the conductor into a predetermined shape. A resistor having a predetermined shape and a predetermined resistance value can be formed without being affected by alteration.

  Hereinafter, an embodiment of a printed wiring board according to the present invention will be described with reference to the drawings. Note that the present invention is not limited to such an embodiment. In addition, in the drawings used in the following description, in order to make the features of the present invention easier to understand, there is a case where a main part is shown in an enlarged manner for convenience, and the dimensional ratio of each component is the same as the actual one. Not necessarily.

  FIG. 1 is a cross-sectional view showing an example of the printed wiring board of the present invention. The printed wiring board 10 includes an insulating portion 11 and a first conductive portion 12 formed on one surface 11 a of the insulating portion 11. The first conductive portion 12 may be, for example, a conductor (wiring layer) formed in a predetermined pattern.

  In addition, a second conductive portion 13 formed away from the first conductive portion 12 so as not to be in direct contact with the first conductive portion 12, the first conductive portion 12, and the one surface 11 a of the insulating portion 11 A third conductive portion 14 that electrically connects the second conductive portion 13 is formed.

  The second conductive portion 13 is formed of an electric resistor and functions as a thin film resistance element. The third conductive portion 14 functions as a connection terminal for electrically connecting the second conductive portion 13 constituting the resistor to the first conductive portion 12 constituting the wiring layer, and is entirely formed of a noble metal. Yes.

  The thickness t1 of the second conductive part is preferably formed to be the same as or thinner than the thickness t2 of the first conductive part 12.

  According to the printed wiring board 10 of the present invention having such a configuration, the second conductive portion 13 itself forming the resistor is formed with a constant thickness without a step. Accordingly, the second conductive portion 13 can be formed with high accuracy so that the resistance value becomes a predetermined (target) value. That is, in the multilayer printed wiring board 101 provided with the conventional resistor as shown in FIG. 4, both ends of the second conductive portion 105 constituting the resistor are covered with parts of the first conductive portions 107a and 107b, respectively. Since the step S swelled in the thickness direction of the two conductive portions 105 is formed, thickness unevenness is likely to occur at the time of forming the step S, and the resistance value may be formed to a predetermined (target) value. It was difficult.

  However, since the second conductive portion 13 constituting the resistor of the present invention is connected to the first conductive portion 12 via the third conductive portion 14, the entire second conductive portion 13 is formed with a constant thickness t1 and without a step. Therefore, it becomes easy to form a thickness and size having a target resistance value, and it is possible to solve problems such as non-uniform resistance values among products and deterioration of yield.

  Further, since the second conductive portion 13 is connected to the first conductive portion 12 forming the wiring via the third conductive portion 14 made of a noble metal, the resistance value is a predetermined value even in a high temperature and high humidity environment. Can be prevented from rising.

  Furthermore, the second conductive portion 13 is connected via the third conductive portion 14 without directly contacting the first conductive portion 12 forming the wiring, so that the thickness t1 of the second conductive portion 13 is set to the first conductive portion 12. It is possible to make it equal to or thinner than the thickness t2. That is, as in the case of the conventional multilayer printed wiring board 101 shown in FIG. 4, when both ends of the second conductive portion 105 are covered with a part of the first conductive portions 107 a and 107 b and directly connected, If the thickness is made thinner than the thickness of the first conductive portions 107a and 107b, the thickness of the second conductive portion 105 may become extremely thin or cut at the step S, which may cause poor connection.

  However, whether the thickness t1 of the second conductive portion 13 is the same as the thickness t2 of the first conductive portion 12 by indirectly connecting the second conductive portion 13 to the first conductive portion 12 via the third conductive portion 14. Even if it is thinner than that, there is no electrical connection failure. By making the thickness t1 of the second conductive portion 13 the same as or thinner than the thickness t2 of the first conductive portion 12, it is possible to realize a higher resistance value in the same area. Can be reduced in size and thickness.

  The insulator 11 may be formed of an insulating film made of polyimide, LCP, or the like, for example. The 1st electroconductive part 12 should just be formed with the thin film which consists of electroconductive metals, such as Cu and Al, for example. The 2nd electroconductive part 13 should just be printed and apply | coated the resistor paste. The third conductive portion 14 only needs to be printed and coated with a noble metal paste made of a noble metal such as Au, Ag, or Pt.

  FIG. 2 is a cross-sectional view showing a multilayer printed wiring board of the present invention in which a plurality of the printed wiring boards described above are laminated in the thickness direction. The multilayer printed wiring board 20 includes a plurality of printed wiring boards 10 shown in FIG. The printed wiring boards 10 and 10 are laminated via a junction insulating part 21. The bonding insulating portion 21 serves as an adhesive layer that bonds the printed wiring boards 10 and 10 together.

  In addition, the multilayer printed wiring board 20 is formed with an interlayer conducting portion 22 that conducts the first conducting portions 12, 12 arranged in an overlapping manner. The interlayer conductive portion 22 may be, for example, a member in which a conductive material is filled in a through hole that penetrates the insulator 11.

  The bonding insulating portion 21 forming the adhesive layer may be formed from, for example, a thermoplastic resin or a thermosetting resin. Moreover, as the conductive material, for example, a conductive paste made of a conductive metal such as Al or Cu is preferably used.

  In addition to the form in which the above-described interlayer conductive portion is filled with a conductive material inside the through hole as shown in FIG. 2, for example, as shown in FIG. 3, a conductive material is formed on the inner wall surface of the through hole by plating. It may be a thing. The interlayer conductive portion 31 is formed by plating a conductive metal such as Al or Cu with a predetermined thickness on the inner wall surface of the through hole 32 penetrating from the upper layer to the lower layer of the multilayer printed wiring board 30.

  In the multilayer printed wiring boards 20 and 30 configured as shown in FIGS. 2 and 3, the thickness of the second conductive portion 13 constituting each printed wiring board 10 is the same as the thickness of the first conductive portion 12. The thickness of the multilayer printed wiring boards 20 and 30 can be reduced and made thinner.

  FIG. 4 is a cross-sectional view showing the printed wiring board manufacturing method of the present invention step by step. When a printed wiring board is manufactured by the manufacturing method of the present invention, first, an insulator 11 is prepared, and a conductor 15 is formed on one surface 11a of the insulator 11 (see FIG. 4A). The insulator 11 may be an insulating film made of, for example, polyimide or LCP. The conductor 15 may be a metal thin film in which a conductive metal such as Cu or Al is formed with a uniform thickness.

  Next, the first conductive portion 12 forming a wiring layer having a predetermined shape is formed by photolithography or the like using the conductor 15 (see FIG. 4B): the first conductive portion having a predetermined shape on one surface of the insulating portion. Part forming step).

  Then, a resistor paste is provided by printing or coating at a predetermined position apart from the first conductive portion 12. As a result, a second conductive portion 13 that forms a resistor is formed in a separated state not in contact with the first conductive portion 12 (see FIG. 4C): directly contact the first conductive portion using the resistor paste. Step of forming the second conductive portion so as not to).

  Further, a noble metal paste is provided by printing or coating at a predetermined position where the first conductive portion 12 and the second conductive portion 13 are electrically connected. Thereby, the 3rd electroconductive part 14 which makes the connection terminal which conducts between the 1st electroconductive part 12 and the 2nd electroconductive part 13 is formed (refer FIG.4 (d): 1st electroconductive part using a noble metal paste) And a step of forming a third conductive part for electrically connecting the second conductive part).

  Through the above steps, the printed wiring board 10 of the present invention is formed. Thereafter, a plurality of printed wiring boards 10 and 10 may be laminated or a protective layer may be formed according to the purpose.

  According to the above-described method for manufacturing a multilayer printed wiring board of the present invention, the second conductive portion 13 that forms a resistor can be formed with a constant thickness without a step. Therefore, the second conductive portion 13 can be formed with high accuracy so that the resistance value becomes a predetermined (target) value. That is, since the second conductive portion 13 is connected to the first conductive portion 12 via the third conductive portion 14, the entire second conductive portion 13 can be formed with a constant thickness and no step. For this reason, it becomes easy to form in the thickness and size which have the target resistance value, and it can prevent generation | occurrence | production of the nonuniformity of resistance value between products, the deterioration of a yield, etc.

  Further, by connecting the second conductive portion 13 via the third conductive portion 14 without directly contacting the first conductive portion 12 forming the wiring, the thickness of the second conductive portion 13 can be reduced without causing conduction failure. The thickness can be the same as or thinner than the thickness of the first conductive portion 12, and a higher resistance value can be realized in the same area, and the printed wiring board 10 can be reduced in size and thickness. Can do.

  Further, since the second conductive portion 13 that forms the resistor is formed in a later process than the formation of the first conductive portion 12 that forms the wiring, the first conductive portion is etched by etching the conductor 15 into a predetermined shape. Therefore, a resistor having a predetermined shape and a predetermined resistance value can be formed without being affected by corrosion or alteration due to etching means (acidic or alkaline chemicals).

Examples in which the effects of the present invention are verified will be described below. The printed wiring board shown in FIG. Moreover, the printed wiring board shown in FIG. 5 was made into the comparative example.
Hereinafter, the constituent materials and sizes of each part in the present invention example and the comparative example are listed.
(1) Constituent materials-Substrate (insulator): PI (invention example, comparative example)
Wiring (first conductive part): Cu (invention example, comparative example)
Resistor (second conductive part): carbon paste (invention example, comparative example)
Connection terminal (third conductive part): Ag paste (example of the present invention)
Note that an Ag paste is applied to the connection portion (step) between the resistor and the wiring in the comparative example (see the lower enlarged view of FIG. 5).
(2) Resistor size ・ Example of the present invention: 1.6 mm (length) × 0.5 mm (width) × 10 μm (thickness)
Comparative example: 2 mm (length) x 0.5 mm (width) x 25 µm (thickness)
(3) Theoretical resistance value Based on the resistance value of the carbon paste actually used (10 kΩ / □) based on the above-mentioned size of the resistor, the theoretical resistance value of each resistor is:
1.6 ÷ 0.5 ÷ 1 × 10 = 32 kΩ (example of the present invention)
2 / 0.5 / 2.5 × 10 = 16 kΩ (comparative example)

  From the above (3) theoretical resistance value, the printed wiring board of the present invention can obtain a resistance value twice as large as that of the conventional printed wiring board in the same occupied area. That is, if the resistance value is the same, it is possible to realize a printed wiring board having a resistor having substantially the same resistance value with half the occupied area of the comparative example.

  Next, Table 1 shows the results of actually measuring three samples of the resistance values of the resistors of the present invention and the comparative example.

According to the results shown in Table 1, the actually measured resistance value of the resistor in the printed wiring board of the present invention example is almost the same as the theoretical resistance value, but in the comparative example, the actually measured resistance value is the theoretical value. It is lower than the resistance value. This is probably because the portion where the resistor is in direct contact with the wiring becomes a step and a portion with a large cross-sectional area is generated, so that the actual resistance value has decreased.
From the above results, according to the printed wiring board of the present invention example, it is possible to obtain a resistance value closer to the design value than the conventional printed wiring board, and the built-in resistor has a large resistance value in a small area. It was confirmed that it was obtained.

It is sectional drawing which shows an example of the printed wiring board of this invention. It is sectional drawing which shows an example of the multilayer printed wiring board of this invention. It is sectional drawing which shows another example of the multilayer printed wiring board of this invention. It is sectional drawing which shows an example of the manufacturing method of the printed wiring board of this invention. It is sectional drawing which shows an example of the conventional multilayer printed wiring board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Printed wiring board, 11 Insulator, 12 1st electroconductive part, 13 2nd electroconductive part, 14 3rd electroconductive part.

Claims (4)

An insulating portion; a first conductive portion formed on one surface of the insulating portion; a second conductive portion formed on one surface of the insulating portion so as not to be in direct contact with the first conductive portion; A printed wiring board comprising at least a first conductive part and a third conductive part for electrically connecting the second conductive part,
The printed wiring board, wherein the second conductive portion is made of an electric resistor, and the third conductive portion is made of a noble metal.   The printed wiring board according to claim 1, wherein the second conductive portion is formed to have the same thickness as the first conductive portion or thinner than the first conductive portion.   A multilayer printed wiring board comprising: an interlayer conductive portion that stacks a plurality of the printed wiring boards according to claim 1 via a junction insulating portion, and that electrically connects the first conductive portions arranged in an overlapping manner.   Forming a first conductive portion having a predetermined shape on one surface of the insulating portion; forming a second conductive portion so as not to directly contact the first conductive portion using a resistor paste; and precious metal paste And a step of forming a third conductive portion that electrically connects the first conductive portion and the second conductive portion. A method for manufacturing a printed wiring board, comprising:

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