JP2005240127A - Resistance element and printing circuit board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printing circuit board containing a resistance element which has a high specific resistance, is less changed in specific resistance in spite of a heat history after formation and is formed of a plating resistance film by electroless plating capable of forming the metallic film with high accuracy in fewer processes. <P>SOLUTION: The plating film has the plating resistance film in which the rate of change in the specific resistance after heating at 200°C is reduced by ≥10% as compared with before the heating, wherein the specific resistance of the plating resistance film before the heating is ≥5,000 μΩcm. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a resistance element used in an electronic device or the like, and relates to a resistance element having good thermal stability and a printed wiring board on which the resistance element is mounted.

  In recent years, with the progress of miniaturization and weight reduction of devices such as mobile phones and digital cameras, conventional mounting technologies such as miniaturization of parts and reduction of the interval between parts have become difficult to deal with, and expectations for printed wiring boards with built-in parts Is growing. Passive components (capacitors, resistors, inductors) can satisfy the characteristics required by device manufacturers relatively easily if existing components are used, but there is a problem that the substrate containing the components becomes thick. There is an urgent need to develop materials that can sufficiently satisfy the characteristics of thin parts and membrane elements.

  Under such circumstances, development of a small and high resistance resistance element has been urgently developed, and an example is resistance due to a carbon-containing paste. However, since this is formed by a printing method, there is a problem that it is difficult to obtain accuracy. As another example, there is a method of forming a metal film on a substrate and patterning it into a desired shape to form a resistor. This can be expected to have high shape accuracy, but is not practical because the specific resistance changes when heat is applied after the half surface is formed. A metal resistance film showing a high resistance value is unstable with respect to heating (Patent Document 1), and is unsuitable for mounting on a printed wiring board in which reflow and baking are performed many times.

  As a resistance film that shows a stable resistance value after baking, there has been a resistance film formed by electrolytic plating in the past (Patent Document 2), but it requires a process of forming a metal foil part separately and bonding it to a substrate. , It was time consuming. The sheet resistance was not so high.

Therefore, a material that can be formed by electroless plating that can be directly laminated on a substrate, has high sheet resistance, and has a specific resistance that hardly changes even after heating has been desired.
Patent No. 3014958 U.S. Pat. No. 4,808,967

  The object of the present invention is that the specific resistance is high, the change in the specific resistance is small due to the thermal history after formation, and the plating resistance film is formed by electroless plating that can form a highly accurate metal film with fewer steps. Another object of the present invention is to provide a printed wiring board incorporating a resistive element.

  1st invention which concerns on Claim 1 is a resistance element which has a plating resistance film from which the rate of change of the specific resistance after heating at 200 degreeC does not fall 20% or more compared with before heating.

  The second invention according to claim 2 is the resistance element according to claim 1, which has a plating resistance film having a specific resistance before heating of 5000 μΩcm or more.

  A third invention according to claim 3 is the resistance element according to claim 1 or 2, wherein the plating resistance film is an electroless plating resistance film.

  A fourth invention according to a fourth aspect is the resistance element according to any one of the first to third aspects, wherein the plating resistance film contains nickel and phosphorus.

  According to a fifth aspect of the present invention, there is provided a printed wiring board in which the resistance element according to any one of the first to fourth aspects is provided on a substrate.

  A sixth invention according to claim 6 is the printed wiring board according to claim 5, wherein the resistor element and the wiring pattern are provided on the same layer.

  A seventh invention according to claim 7 is the printed wiring board according to claim 6, wherein the wiring pattern is subjected to a roughening treatment.

  According to the present invention, it is possible to provide a highly reliable printed wiring board that has a high yield and does not change during subsequent manufacturing processes or actual use because the resistance value of the resistance element once formed can be kept low. it can. In addition, since the specific resistance of the plating resistance film shows a high value that has not been conventionally obtained, a thin and small resistance element can be formed. In addition, since the resistance element can be formed by electroless plating, the plating resistance film is formed directly on the substrate, and therefore there is no step of attaching the metal foil to the substrate, so that the efficiency of the manufacturing process can be increased.

  The plating resistance film characterizing the printed wiring board according to the present invention can be formed on an arbitrary layer of the insulating layer constituting the printed wiring board. The insulating layer here is a printed circuit board in which an insulating material is laminated by embedding / forming a wiring or a passive element in a lower layer even in a core substrate such as a glass epoxy substrate generally held as a core layer of the printed circuit board. But you can.

  On this insulating layer, a resistance metal film is formed by plating. The plating is preferably electroless plating because a thin and uniform plating resistance film can be formed on the entire insulating layer.

  The plating resistance film formed here should contain nickel and phosphorus, and if it is a resistance metal film containing a third component, the sheet resistance value is high, and even if heating is performed after plating formation, the sheet resistance changes. It is more preferable because it can be suppressed. Specific examples of the third component include iron, carbon, and molybdenum.

  The plating solution for forming the plating resistance film in the present invention includes an electroless plating solution composed of nickel, phosphorus, iron, nickel, phosphorus, tungsten, nickel, phosphorus, molybdenum, nickel, phosphorus, rhenium, nickel, phosphorus, chromium. Can be used. In order to stably form a high resistance plating resistance film, a plating solution having a high volume resistivity and a slow plating deposition rate is preferable. In addition, the resistance value and the plating deposition rate can be adjusted by adjusting the phosphorus concentration, complexing agent, reducing agent concentration, temperature and pH of the plating solution.

  The plating resistance film is processed by etching or the like so as to form a resistance element pattern to form a conductor layer, and the thus laminated conductor layer is processed into a desired wiring pattern. Alternatively, after the plating resistance film is formed, a conductor layer is formed, the conductor layer and the plating resistance film are patterned so as to have a desired wiring pattern and a resistance element shape, and then unnecessary conductor layers between the resistance element electrodes are removed to provide resistance. Complete the device.

  In addition, it is good to give the heat resistance (preferably 180 degreeC or more) after film formation to the board | substrate with which the plating resistance film was formed, and to stabilize the specific resistance of a plating resistance film. In consideration of a general printed wiring board manufacturing process, a resistance material that can withstand heating up to about 260 ° C. is preferable, and a material that does not decrease in resistivity by 10% or more after heating at about 200 ° C. is preferable.

  Further, when an insulating layer is formed, a surface roughening treatment is applied to the wiring pattern in order to improve adhesion with the insulating material. In addition, the same treatment may be applied to the plating resistance film portion. Examples of the surface roughening treatment include Circubond (made by Shipley Far East) and CZ treatment (made by MEC). These treatments are performed by appropriately selecting from the compatibility between the metal material and the insulating material.

  After the surface roughening treatment, the resistance element is trimmed to adjust the capacitance, and after that, an insulating material is stacked to form an insulating layer, and vias and upper wiring layers are formed as necessary. A printed wiring board.

  Hereinafter, the present invention will be described in detail by way of examples.

  A substrate surface made of BT (bismaleimide triazine) having a thickness of 0.4 mm was washed with a conditioning cleaner (Okuno Pharmaceutical Co., Ltd .: OPC-380 Condy Clean M), and a Pd-Sn colloid solution (Okuno Pharmaceutical Co., Ltd .: OPC-80 catalyst) was applied with a Pd catalyst, and activated using an activator (Okuno Pharmaceutical Co., Ltd .: OPC-555 Accelerator M). Next, about 0.2 μm was plated with an electroless nickel / iron / phosphorus alloy plating solution to form a plating resistance film made of nickel / iron / phosphorus. The specific resistance of the plating resistance film at this time was 6800 μΩcm.

  On the plating resistance film thus formed, about 0.3 μm was plated by an electroless copper process (Shipley Fareast CUPOSIT), and about 10 μm was plated by electrolytic copper plating to obtain a conductor layer.

  A negative dry film resist (manufactured by Hitachi Chemical Co., Ltd .: RY-3215) was applied. Next, the resist was exposed through a negative and selectively exposed to ultraviolet light. The negative was designed so that the resist on the conductor layer in the portion to be the wiring pattern was exposed. Unexposed portions of the resist were removed at 30 ° C. using a developer (1% aqueous sodium carbonate solution).

  After the exposed conductor layer is removed by etching using ferric chloride solution at 65 ° C., an unnecessary plating resistance film is formed at 90 ° C. using a copper sulfate-sulfuric acid solution (copper sulfate 250 g / L, sulfuric acid 5 ml / L). Etching was removed. Next, the resist was removed with a stripping solution (5% aqueous sodium hydroxide solution) so that the conductor layer remained on the wiring pattern and the resistance element.

  A negative dry film resist (manufactured by Hitachi Chemical Co., Ltd .: RY-3215) was applied. The resist was then exposed to UV light through a negative. The pattern at this time was designed such that a portion other than the element electrode on the resistance element was exposed and the resist remained. The unexposed portion of the resist (that is, the portion where the plating resistance film is exposed) was removed at 30 ° C. using a developer (1% aqueous sodium carbonate solution).

  Using an alkaline etching solution (Asahi Denka Kogyo Co., Ltd .: Adeka Kernica AN8), the conductive layer on the portion of the resistive element that becomes the resistor was removed by etching to form a resistive element and a wiring pattern.

  Next, surface roughening treatment was performed on the metal part with a circular bond. Thereafter, the entire substrate was heat-treated at 230 ° C. for 30 minutes in a nitrogen atmosphere. The specific resistance of the resistance element after the heat treatment was 6300 μΩcm.

  After the surface roughening treatment, the capacity was adjusted while measuring the resistance value with a laser processing machine. Thereafter, BT resin was laminated to form an insulating layer, and after a wiring pattern was formed on the insulating layer, the element was conducted through a via hole to obtain the printed wiring board of the present invention.

  It can be seen that the plating resistance film of the present invention thus produced has a high specific resistance before heating, and the high resistance value is maintained after heating.

Claims (7)

  A resistance element having a plating resistance film in which the rate of change in specific resistance after heating at 200 ° C. does not decrease by 10% or more compared to before heating.   The resistance element according to claim 1, further comprising a plating resistance film having a specific resistance before heating of 5000 μΩcm or more.   The resistance element according to claim 1, wherein the plating resistance film is an electroless plating resistance film.   The resistance element according to claim 1, wherein the plating resistance film contains nickel and phosphorus.   A printed wiring board comprising the resistance element according to claim 1 provided on a substrate.   6. The printed wiring board according to claim 5, wherein the resistance element and the wiring pattern are provided on the same layer.   The printed wiring board according to claim 6, wherein the wiring pattern is roughened.