JP2007242795A - Printed wiring board, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed wiring board equipped with a resistor which can secure a stable resistance value and does not need a filling process of a protection layer after laser trimming, and to provide its manufacturing method. <P>SOLUTION: The manufacturing method of the printed wiring board having the resistor coated with the protection layer between wiring patterns comprises a process wherein a circuit is formed at least on a resistor layer and a metal layer which are stacked in order on an insulation substrate to form a desired wiring pattern; a process wherein an etching resist pattern is formed on the wiring pattern; a process wherein by removing part of the wiring pattern exposed from the etching resist pattern by etching, the resistor is formed between wiring patterns; and a process wherein, with the remaining etching resist pattern, the protection layer which protects the resistor and allows laser for laser trimming to pass through it is formed on the surface of the resistor exposed by the etching. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a printed wiring board and a manufacturing method thereof, and more particularly to a printed wiring board including a resistor covered with a protective layer between wiring patterns and a manufacturing method thereof.

  Along with the recent downsizing and higher performance of equipment, printed circuit boards to be mounted are also required to have smaller and higher density wiring. In addition to chip components that have been mounted on the outer layers of printed circuit boards, Thus, a form in which a part is formed on the inner layer by a method such as pattern formation is being adopted.

  As a method for manufacturing such a printed wiring board, manufacturing methods as shown in FIGS. 4 to 5 are already known.

This conventional manufacturing will be described as follows.
That is, first, as shown in FIG. 4A, a resistance layer 2 made of nickel-phosphorous plating is formed on the surface of the insulating base 1, and then a metal layer such as copper plating is formed on the surface of the resistance layer 2. 3 is formed.

  Next, as shown in FIG. 4B, a first etching resist pattern 4 is formed on the metal layer 3, and then the metal layer 3 exposed from the first etching resist pattern 4 is etched. Is removed (see FIG. 4C).

  Next, as shown in FIG. 4D, the first etching resist pattern 4 is peeled off, and then an etching process is performed using the metal layer 3 as an etching resist to remove the exposed resistance layer 2. (See FIG. 5 (e)).

  Next, as shown in FIG. 5F, a second etching resist pattern 5 is formed on the wiring pattern, and then a part of the wiring pattern exposed by the etching process is removed (FIG. 5 ( g)), and the second etching resist pattern 5 is peeled to obtain a printed wiring board Pa4 in which a resistor is formed between specific wiring patterns (see FIG. 5H).

  However, the conventional manufacturing method has the following problems.

  In other words, the metal thin film has excellent temperature characteristics and is excellent for high-precision resistance applications. However, since it is formed with a very thin film of 1 μm or less, scratches may occur due to transportation or handling, and moisture or oxidation may occur. As a result, the resistance value changes and the predetermined accuracy cannot be achieved.

  Therefore, as shown in FIG. 6A, a manufacturing method in which a protective layer 9 is provided so as to cover the printed circuit board Pa4 in which a resistor is formed between specific wiring patterns, as shown in FIG. Is already known (see, for example, Patent Document 1).

  However, the above manufacturing method has the following problems.

  In general, printed wiring boards incorporating such passive components have been required to be incorporated with organic materials due to demands for weight reduction and higher density.

  In addition, the resistor is likely to generate microcracks due to thermal strain caused by the heat of the laser, and further, the microcracks progress with time and the resistance value is likely to change with time (drift).

  Therefore, in order to increase the reliability of the resistor, it is necessary to suppress the occurrence and progression of microcracks and minimize the change in resistance over time.

  Therefore, it is necessary to form a protective layer 9 such as an overcoat so as to cover the resistor before trimming.

  However, when laser trimming is performed using an organic material, the insulating base 1 and the protective layer 9 have substantially the same energy absorption rate, and therefore the protective layer 9 and the resistive layer 2 are removed without breaking the insulating base 1. It is difficult.

As a result, when laser trimming is performed on the resistor of the printed wiring board Pa5 obtained by the above manufacturing method, the protective layer 9 is also destroyed at the same time, and as shown in FIG. 6B, the protective layer 9 Since a laser-processed hole 9a is generated, a process for newly filling the generated hole 9a using the insulating resin 10 as shown in FIG. 6C is required.
JP 2001-291603 A

  The present invention has been made to solve the above-mentioned problems, and the problem is that a print having a resistor that ensures a stable resistance value and does not require a step of filling a protective layer processed hole after laser trimming. It is to provide a wiring board and a manufacturing method thereof.

  In order to solve the above problems, the present invention according to claim 1 is a printed wiring board including a resistor covered with a protective layer between wiring patterns, wherein the protective layer is transparent to a laser for laser trimming. It is characterized by having.

  As described above, since the protective layer has laser transparency, when the resistor whose surface is covered with the protective layer is subjected to laser trimming, only the resistor can be removed by using, for example, a laser having a specific wavelength that is easily transmitted. Therefore, the conventional process of filling the protective layer processed hole after laser trimming is not required, and the manufacturing process after laser trimming can be simplified while ensuring a stable resistance value.

  According to a second aspect of the present invention, in the printed wiring board, the protective layer is a protective layer made of an ultraviolet transparent insulating resin.

  Thereby, the manufacturing process after laser trimming can be simplified using the conventional manufacturing process of a printed wiring board while ensuring a stable resistance value.

  According to a third aspect of the present invention, in the printed wiring board, the wavelength of the laser is in the range of 300 nm to 700 nm.

  Thereby, even if the insulating base material is an organic base material, the laser is not absorbed by the protective layer, and the laser does not destroy the insulating base material under the resistance layer, and only the resistor is irradiated by the laser. Can be trimmed.

  According to a fourth aspect of the present invention, in the printed wiring board, the protective layer has an ultraviolet transmittance in the wavelength range of 30% or more.

  Thereby, even if the said insulating base material is an organic base material, it can trim only the said resistor with a laser, without receiving the big damage which has a quality problem in base material itself.

  Moreover, the present invention according to claim 5 is characterized in that, in the printed wiring board, the insulating base material of the printed wiring board contains an organic material.

  Thereby, the manufacturing process after laser trimming can be simplified using the conventional manufacturing process of a printed wiring board while ensuring a stable resistance value.

  According to a sixth aspect of the present invention, in the printed wiring board, the resistor is made of a metal thin film.

  As a result, the volume resistance value of the metal and the thickness of the metal thin film are constant, and the resistance value is generally stable compared to other resistors such as thick film paste resistors. A resistance value can be obtained, and it is possible to minimize the minute pieces and gas that may be generated by trimming between the resistance layer and the protective layer, and to ensure the stability of the resistance value after trimming and to protect the layer. It is possible to reduce deformation such as surface swelling and depression.

  According to a seventh aspect of the present invention, in the printed wiring board, the resistor is built in the printed wiring board.

  As a result, it is possible to use the resistor that has simplified the manufacturing process after laser trimming while securing a stable resistance value as a part of the printed wiring board with a built-in component, and the scope of use of the present invention has jumped. Improve.

  Further, the present invention according to claim 8 is a method of manufacturing a printed wiring board including a resistor covered with a protective layer between wiring patterns, and includes a resistance layer sequentially laminated on at least an insulating substrate, Forming a circuit on the metal layer, forming a desired wiring pattern, forming an etching resist pattern on the wiring pattern, and removing a part of the wiring pattern exposed from the etching resist pattern by etching Forming a resistor between the wiring patterns and protecting the resistor on the surface of the resistor exposed by the etching while leaving the etching resist pattern, and laser trimming laser Forming a protective layer that transmits light.

  As described above, since only the resistor can be trimmed by laser from above the protective layer, trimming can be performed in a state where the resistor is protected from an etching solution or the like that unnecessarily changes the resistance value. A stable resistance value can be ensured.

  The present invention according to claim 9 further includes a step of trimming only the resistor by a laser from above the protective layer after the step of forming the protective layer in the method for manufacturing the printed wiring board. Features.

  Thereby, since only the resistor is trimmed by the laser, the printed wiring board on which the resistor is formed can be obtained without filling the protective layer processed hole after laser trimming as in the prior art.

  According to a tenth aspect of the present invention, in the method for manufacturing the printed wiring board, the protective layer is a protective layer made of an ultraviolet transparent insulating resin.

  As a result, a printed wiring board on which a resistor having a simplified manufacturing process after laser trimming is formed can be obtained using a conventional printed wiring board manufacturing process while securing a stable resistance value.

  The present invention according to claim 11 is characterized in that, in the method for manufacturing a printed wiring board, the wavelength of the laser is in a range of 300 nm to 700 nm.

  Thereby, even if the insulating base material is an organic base material, the laser is not absorbed by the protective layer, and the laser does not destroy the insulating base material under the resistance layer, and only the resistor is irradiated by the laser. Can be trimmed.

  The invention according to claim 12 is characterized in that, in the method for producing a printed wiring board, the protective layer has an ultraviolet transmittance of 30% or more.

  Thereby, even if the said insulating base material is an organic base material, only the said resistor can be trimmed with the laser of the wavelength which does not receive the big damage which has the problem on quality in the said base material itself.

  Moreover, this invention which concerns on Claim 13 is a manufacturing method of the said printed wiring board, The said insulating base material contains the organic material, It is characterized by the above-mentioned.

  As a result, a printed wiring board on which a resistor having a simplified manufacturing process after laser trimming is formed can be obtained using a conventional printed wiring board manufacturing process while securing a stable resistance value.

  According to a fourteenth aspect of the present invention, in the printed wiring board manufacturing method, the resistor is made of a metal thin film.

  As a result, the volume resistance value of the metal and the thickness of the metal thin film are constant, and the resistance value is generally stable compared to other resistors such as thick film paste resistors. A resistance value can be obtained, and it is possible to minimize the minute pieces and gas that may be generated by trimming between the resistance layer and the protective layer, and to ensure the stability of the resistance value after trimming and to protect the layer. It is possible to reduce deformation such as surface swelling and depression.

  According to a fifteenth aspect of the present invention, in the method for manufacturing a printed wiring board, the resistor is built in the printed wiring board.

  As a result, it is possible to use the resistor, which has simplified the manufacturing process after laser trimming, while securing a stable resistance value, as a part of the printed wiring board with built-in components, and the scope of use of the present invention is dramatically increased. To improve.

  ADVANTAGE OF THE INVENTION According to this invention, the printed wiring board provided with the resistor and its manufacturing method which do not need the filling process of the protective layer process hole after laser trimming can be provided, ensuring a stable resistance value.

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

FIG. 2 (n) shows a schematic cross-sectional view of the resistor-embedded printed wiring board Pa1 according to the present invention. The printed wiring board Pa1 includes a resistor 2a between the wiring patterns 3a and the resistor. The body 2a is covered with a protective layer 6 having laser transparency for laser trimming.
Such printed wiring board Pa1 of the present invention is manufactured as follows.

  First, as shown in FIG. 1A, a metal layer 3 with a resistance layer in which a resistance layer 2 has already been formed is laminated on an insulating substrate 1 (see FIG. 1B). Here, examples of the resistance layer 2 include nickel, nickel-phosphorus, nickel-chromium, nickel-silicon-chromium, nickel-phosphorus-tungsten, and the metal layer 3 is generally made of copper or the like. It is mentioned as preferable. The resistance layer 2 is formed by electroplating, electroless plating, sputtering, CVD, or the like, and the thickness is preferably 1 μm or less.

Next, a resistance film and an electrode are formed by a subtractive method to obtain a structure in which a resistor 2a is formed between specific wiring patterns 3a (see FIGS. 1C to 2M).
In addition, although embodiment by the subtractive method using copper foil with a resistance layer is demonstrated here, implementation by the additive method using the electroless-plating method etc. may be sufficient.

Next, a protective layer 6 is formed on the surface, and a printed wiring board Pa1 having a resistor 2a covered with a protective layer 6 having laser transparency for laser trimming is obtained between the wiring patterns 3a (FIG. 2 ( n)).
The protective layer 6 is an ink-like protective layer applied by a printing method, a spray method, a spin coating method, a dip coating method, a bar coating method, a roll coating method, a curtain coating method, or the like, or a protective layer that has been formed into a film in advance. It is preferable to form by laminating. The protective layer 6 preferably transmits 30% or more of the laser to be laser trimmed. When the transmittance is less than 30%, energy is absorbed by the protective layer, the protective layer is processed, and energy required for processing does not reach the resistance layer below the protective layer, and trimming may not be performed.

  Thus, by trimming the resistor of the printed wiring board Pa1 from above the protective layer 6 using a laser, a process of filling a protective layer processed hole after laser trimming is not necessary while ensuring a stable resistance value. In addition, a printed wiring board Pa2 on which a resistor is formed can be obtained (see FIG. 2 (q)). At this time, the wavelength of the laser used for processing is preferably 300 nm to 700 nm. For example, a wavelength of 532 nm, which is the second harmonic of an Nd: YAG (neodymium, yttrium, aluminum, garnet) laser, is preferably used. When the wavelength is less than 300 nm, for example, when a wavelength of 266 nm, which is the fourth harmonic of an Nd: YAG laser, is used, energy is absorbed in the protective layer and processed simultaneously. Also, when the wavelength exceeds 700 nm, for example, when the wavelength of 1064 nm, which is the fundamental wave of the Nd: YAG laser, is used, the insulating base material under the resistance layer is destroyed at the same time as the protective layer, and the substrate quality is significantly deteriorated. There is also.

  The most notable point in the present invention is that the resistor is covered with a protective layer that transmits a laser having a specific wavelength. Thereby, the resistor can be trimmed without destroying the protective layer from above the protective layer, and the manufacturing process after laser trimming can be simplified while ensuring a stable resistance value.

  EXAMPLES Hereinafter, an Example is given about the manufacturing method of the printed wiring board of this invention, and it demonstrates further with FIGS. 1-3.

Example 1
In this example, as the insulating material 1, GEA-679F (thickness: 100 μm) manufactured by Hitachi Chemical Co., Ltd. was used. Moreover, as the resistance layer 2 and the metal layer 3, 18-micrometer copper foil with a 50-ohm resistance layer made from omega ply was used. As the first etching resist pattern 4, RY3215 manufactured by Hitachi Chemical Co., Ltd. was used. As the second etching resist pattern 5, RY3237 manufactured by Hitachi Chemical Co., Ltd. was used.

  First, as shown in FIG. 1 (a), the resistance layer 2 already formed with the metal layer 3 with the resistance layer and the insulating substrate 1 are converted into a high-temperature vacuum laminating press as shown in FIG. 1 (b). Were laminated. The lamination conditions were a lamination temperature profile with a peak of 185 ° C., a lamination pressure of 2.5 MPa, and a vacuum condition of 20 torr.

  Next, the surface of the metal layer 3 with a resistance layer was roughened by a soft etching process as a pretreatment for circuit forming film lamination. NPE-300 manufactured by Mitsubishi Gas Chemical Co., Ltd. was used as the chemical solution for the soft etching treatment.

  Then, as shown in FIG.1 (c), the film 4 for circuit formation was laminated on the surface of the said metal layer 3 with a resistance layer using the auto cut laminator. The laminating temperature was set at 110 ° C., and the laminating speed was 100 cm / min.

Next, exposure of an exposure amount of 65 mJ / cm ² was performed using a negative pattern film so that the circuit forming film could be cured in a predetermined pattern. An ultra-high pressure mercury lamp was used as the light source of the exposure machine.

  After exposure, it was developed with 1% sodium carbonate. The liquid temperature was 30 ° C., and the development time was 30 seconds. After development, the state shown in FIG.

  Next, the metal layer 3 was etched with an alkaline etchant. The etching solution was an A process manufactured by Meltex, a liquid temperature of 45 ° C., and an etching time of 70 sec. After the etching, the state shown in FIG.

  Thereafter, the resistance layer was etched by dipping in a copper sulfate solution. The liquid temperature was 80 ° C. and the etching time was 7 min. After the etching, the state shown in FIG.

  Next, the circuit-forming film was peeled off with 3% sodium hydroxide. The liquid temperature was 50 ° C. After peeling, the state shown in FIG.

  Next, the surface of the metal layer 3 with a resistance layer was roughened by a soft etching process as a pretreatment for circuit forming film lamination. NPE-300 manufactured by Mitsubishi Gas Chemical Co., Ltd. was used as the chemical solution for the soft etching treatment.

  Thereafter, as shown in FIG. 2 (h), the circuit-forming film 5 was laminated on the surface of the metal layer 3 with the resistance layer. An auto-cut laminator was used as a laminator, and laminating conditions were set at a laminating temperature of 110 ° C. and a laminating speed of 100 cm / min.

Next, using a positive pattern film so as to form a resistor with a predetermined pattern, exposure was performed with parallel light at an exposure amount of 100 mJ / cm ² . An ultra-high pressure mercury lamp was used as the light source of the exposure machine.

  After exposure, it was developed with 1% sodium carbonate. The liquid temperature was 30 ° C., and the development time was 90 sec. After development, the state shown in FIG.

  Next, the metal layer 3 with a resistance layer was etched with an alkaline etchant. As an etching solution, Meltex A process, liquid temperature 45 ° C., etching time 60 sec. After the etching, the state shown in FIG.

  Next, the circuit-forming film 5 was peeled off with 3% sodium hydroxide. The liquid temperature was 50 ° C.

  Thereafter, a film composed of 30 to 40% acrylate resin, 10 to 20% epoxy resin, and 30 to 40% pigment is applied to a vacuum at 85 ° C./40 sec using a volume applicator, followed by 85 ° C./90 sec. The protective layer 6 was laminated at / 2 MPa (see FIG. 2 (n)).

Using a negative pattern film, exposure was performed with scattered light at an exposure amount of 630 mJ / cm ² so that a protective layer could be formed in a predetermined pattern so as to cover the exposed resistance portion. A metal halide lamp was used as the light source of the exposure machine.

  After exposure, it was developed with 1% sodium carbonate. The liquid temperature was 30 ° C., and the development time was 180 seconds.

  After the development, post-cure was performed at a temperature of 150 ° C. for 60 seconds.

  As a result, as shown in FIG. 2 (n), a printed wiring board Pa1 having a resistor covered with a protective layer having laser permeability for laser trimming was obtained between the wiring patterns.

  Subsequently, the resistor of the printed wiring board Pa1 was trimmed from above the protective layer 6 using a laser. For trimming, a laser trim machine of a galvano scanner scanning method using a beam having a wavelength of 532 nm, which is the second harmonic of an LD-pumped YAG laser, was used.

  As a result, as shown in FIG. 2 (q), a printed wiring board Pa2 in which only the resistor of the printed wiring board Pa1 was laser-trimmed was obtained.

  In this embodiment, the resistance is formed on one side, but both sides can be manufactured under the same manufacturing conditions.

  Moreover, as shown in FIG. 3, it is also possible to make a multilayer by laminating the insulating base material 7 and the metal layer 8 on the printed wiring board Pa2 and adding a normal printed wiring board manufacturing process. (See FIG. 3C).

  The present invention is not limited to the above embodiment. For example, an insulating layer and a metal layer are formed on the upper and lower sides of the printed wiring boards Pa1 to Pa3 to form a circuit, an interlayer connection via hole, and an interlayer connection through hole. Various modifications can be made by adding a normal printed wiring board manufacturing process such as forming.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic cross-sectional process explanatory drawing which shows the manufacturing method of the printed wiring board of this invention. FIG. 2 is a schematic cross-sectional process explanatory diagram subsequent to FIG. 1. FIG. 3 is a schematic cross-sectional process explanatory diagram subsequent to FIG. 2. Schematic cross-sectional process explanatory drawing which shows the manufacturing method of the conventional printed wiring board. FIG. 5 is a schematic cross-sectional process explanatory diagram subsequent to FIG. 4. Schematic cross-sectional process explanatory drawing which shows the manufacturing method of the other conventional printed wiring board.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 7: Insulating base material 2: Resistance layer 2a: Resistor 3, 8: Metal layer 3a: Wiring pattern 4: First etching resist pattern 5: Second etching resist pattern 6, 9: Protection layer 9a: Processing by laser Hole 10: Insulating resin Pa1-6: Printed wiring board

Claims (15)

  A printed wiring board comprising a resistor covered with a protective layer between wiring patterns, wherein the protective layer has laser transparency for laser trimming.   The printed wiring board according to claim 1, wherein the protective layer is made of an ultraviolet transparent insulating resin.   The printed wiring board according to claim 1, wherein a wavelength of the laser is in a range of 300 nm to 700 nm.   The printed wiring board according to claim 3, wherein the protective layer has an ultraviolet transmittance of 30% or more in the wavelength range.   The printed wiring board according to any one of claims 1 to 4, wherein the insulating base material of the printed wiring board contains an organic material.   The printed wiring board according to claim 1, wherein the resistor is made of a metal thin film.   The printed wiring board according to claim 1, wherein the resistor is built in the printed wiring board.   A method of manufacturing a printed wiring board comprising a resistor covered with a protective layer between wiring patterns, wherein a circuit is formed on at least a resistance layer and a metal layer sequentially laminated on an insulating base material, A step of forming a wiring pattern, a step of forming an etching resist pattern on the wiring pattern, and removing a part of the wiring pattern exposed from the etching resist pattern by etching. Forming a protective layer that protects the resistor and transmits a laser for laser trimming on the surface of the resistor exposed by the etching while leaving the etching resist pattern; and A method for producing a printed wiring board, comprising:   The printed wiring board according to claim 8, further comprising a step of trimming only the resistor by a laser having a wavelength that the protective layer transmits from above the protective layer after the step of forming the protective layer. Production method.   The method for manufacturing a printed wiring board according to claim 8 or 9, wherein the protective layer is made of an ultraviolet-transmissive insulating resin.   The method for producing a printed wiring board according to any one of claims 8 to 10, wherein a wavelength of the laser is in a range of 300 nm to 700 nm.   The method for producing a printed wiring board according to claim 11, wherein the protective layer has an ultraviolet transmittance of 30% or more in the wavelength range.   The method for manufacturing a printed wiring board according to any one of claims 8 to 12, wherein the insulating base material contains an organic material.   The method for manufacturing a printed wiring board according to claim 8, wherein the resistor is made of a metal thin film. The method for manufacturing a printed wiring board according to any one of claims 8 to 14, wherein the resistor is built in the printed wiring board.

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