JP2010050225A - Printed circuit board, method of manufacturing printed circuit board, and electronic equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a printed circuit board prevented from being influenced by external temperature changes to perform high-speed transmission, to provide a method of manufacturing the same, and to provide electronic equipment mounted with such the printed circuit board. <P>SOLUTION: The printed circuit board 1 has a ground insulating layer 10, a circuit pattern 21 formed by patterning a conductor layer 20 laminated on the ground insulating layer 10, and a coating insulating layer 30 covering the circuit pattern 21. The coating insulating layer 30 includes a first coating insulating layer 30 covering the first region 21f of the circuit pattern 21 and a second coating insulating layer 30 covering the second region 21s of the circuit pattern 21, and the second coating insulating layer 30 is formed of an air-containing insulating layer containing air. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a printed wiring board having a coating insulating layer covering a circuit pattern formed by being laminated on a base insulating layer, a printed wiring board manufacturing method for manufacturing such a printed wiring board, and such a printed wiring board. The present invention relates to an electronic device equipped with.

  Conventionally, phenol resin, glass fiber reinforced epoxy, and the like have been used as a constituent material of an insulating layer of a printed wiring board in a hard wiring board system. Moreover, polyester and polyimide resin were used in the flexible wiring board.

  In recent years, with the increase in functionality of electronic devices, higher communication speeds, and higher definition in display devices, there has been a marked increase in the speed of electrical signals flowing in printed wiring boards. The situation that the performance of can not keep up has occurred. When handling high-speed signals, an important issue is how to transmit the signal waveform without dulling.

  The printed wiring board has a structure in which a conductor signal line is sandwiched between insulating resins. Therefore, the decrease in the speed of the signal passing through the signal line (transmission path), the dullness and delay state of the rising and falling waveforms of the signal are closely related to the relative dielectric constant and dielectric loss tangent of the insulating resin used. In general, the lower these values, the more suitable for high-speed transmission.

  Rigid printed wiring boards will soon be replaced with conventional glass epoxy and other materials such as fluorine-based resins such as polytetrafluoroethylene resin with low relative permittivity and dielectric loss tangent, or ceramic. It has become.

  On the other hand, since the flexible wiring board needs flexibility, it is difficult to cope with it because a fluororesin or the like cannot be used easily like the hard wiring board.

  For example, in a field where high-speed transmission corresponding to high definition of the display unit is required simultaneously with high flexibility and bending resistance, such as a portable information terminal, a coaxial thin wire cable is used instead of the conventional flexible wiring board. More and more cases are being adopted.

  However, the part that uses the flexible wiring board, that is, the part that is required to have flexibility and bending resistance is a movable part, and requires performance such as waterproofing and airtightness. When coaxial thin wires are employed in such a portion, it is difficult to achieve a waterproof or airtight structure, and the appearance of a flexible wiring board capable of high-speed transmission has been desired.

  In response to such demands, in recent years, resins called liquid crystal polymers such as wholly aromatic polyesters have appeared. The liquid crystal polymer resin has a characteristic that a relative dielectric constant and a dielectric loss tangent are small as compared with polyimide generally used for flexible wiring boards. However, there are still many problems relating to price, ease of handling, workability, flexibility, bending resistance, and the like.

  In addition, a flexible wiring board structure having a hollow structure using an air layer having a low relative dielectric constant has also been proposed (see, for example, Patent Document 1).

  However, the structure of the printed wiring board described in Patent Document 1 is a structure in which an air chamber is simply provided above the conductor layer. Therefore, there is a risk that the air layer will expand due to temperature rise during mounting or actual use of the printed wiring board, causing blistering to the printed wiring board, or peeling off the insulating resin layer on the air layer. There is.

In addition, there is a problem that the residue during product cleaning and moisture in the air are likely to collect inside the hollow part (air chamber), causing corrosion and deterioration of the circuit, low insulation resistance between circuits, and migration. There is a problem that it cannot be used for a device that is used in a wide temperature and humidity range or in a harsh environment, such as a portable device, and can be used only for a very limited purpose.
JP-A-11-168279

  This invention is made | formed in view of such a condition, and forms the coating insulation layer which coat | covers the transmission line (conductor layer, circuit pattern) in which high-speed transmission is requested | required with the air-containing insulation layer containing air. This prevents condensation, thermal expansion, etc. due to external temperature and humidity changes, prevents deterioration of electrical characteristics such as reduced insulation resistance, or prevents performance deterioration such as blistering, delamination, corrosion, etc. An object of the present invention is to provide a printed wiring board capable of satisfying the requirements.

  In addition, according to the present invention, it is possible to suppress the influence of external temperature and humidity changes by forming the covering insulating layer covering the transmission line (conductor layer, circuit pattern) with an air-containing insulating layer containing air. Another object of the present invention is to provide a printed wiring board manufacturing method for easily and efficiently manufacturing a printed wiring board.

  Another object of the present invention is to provide a highly reliable electronic device that is not easily affected by external temperature and humidity changes by mounting the printed wiring board according to the present invention.

  A printed wiring board according to the present invention includes a base insulating layer, a circuit pattern formed by patterning a conductor layer laminated on the base insulating layer, and a covering insulating layer covering the circuit pattern. The covering insulating layer includes a first covering insulating layer that covers a first region of the circuit pattern, and a second covering insulating layer that covers a second region of the circuit pattern, and the second covering. The insulating layer is formed of an air-containing insulating layer containing air.

  With this configuration, it is possible to suppress the influence of external temperature and humidity changes on the second region, and it is possible to prevent condensation, thermal expansion, and the like in the second region due to external temperature and humidity changes. Further, it is possible to obtain a printed wiring board capable of high-speed transmission by preventing deterioration of electrical characteristics such as a decrease in insulation resistance in the second region, or performance deterioration such as blistering, interlayer peeling, and corrosion.

  In the printed wiring board according to the present invention, the air-containing insulating layer contains hollow microcapsules that enclose air.

  With this configuration, an air-containing insulating layer containing air can be easily configured.

  Further, in the printed wiring board according to the present invention, the air-containing insulating layer contains a filler filling the space between the hollow microcapsules.

  This configuration facilitates the formation and processing of the air-containing insulating layer, and eliminates unnecessary action of air existing between the hollow microcapsules by filling the gaps between the hollow microcapsules, thereby improving the reliability. It becomes possible.

  In the printed wiring board according to the present invention, the second region is extended to serve as a transmission line.

  With this configuration, it is possible to obtain a printed wiring board having a transmission path (cable portion) in which the influence of the surrounding environment is suppressed.

  In the printed wiring board according to the present invention, the first covering insulating layer has an opening opened so as to surround the periphery of the second region, and the second covering insulating layer is formed in the opening. It is formed.

  With this configuration, the second covering insulating layer can be formed easily and with high accuracy, and a printed wiring board having a highly reliable second covering insulating layer can be obtained.

  In the printed wiring board according to the present invention, a protective insulating layer that covers and protects the second covering insulating layer is provided.

  With this configuration, it is possible to protect the surface of the second covering insulating layer and improve the reliability of the second covering insulating layer.

  In the printed wiring board according to the present invention, the base insulating layer, the first covering insulating layer, and the protective insulating layer are formed of a polyimide resin film or a liquid crystal polymer film.

  With this configuration, a printed wiring board with high productivity and high reliability can be configured.

  The printed wiring board manufacturing method according to the present invention includes a base insulating layer, a circuit pattern formed by patterning a conductor layer laminated on the base insulating layer, and a covering insulating layer covering the circuit pattern. A printed wiring board manufacturing method for manufacturing a printed wiring board having a circuit pattern forming step of forming a circuit pattern by patterning a conductor layer laminated on a base insulating layer, and covering a first region of the circuit pattern A first covering insulating layer forming step for forming a first covering insulating layer; and a second covering insulating layer forming step for forming a second covering insulating layer for covering a second region of the circuit pattern. The insulating layer is formed of an air-containing insulating layer containing air.

  With this configuration, a printed wiring board capable of covering the second region of the circuit pattern with an air-containing insulating layer and suppressing the influence of external temperature and humidity changes on the second region is manufactured easily and with high productivity. Can do.

  In the printed wiring board manufacturing method according to the present invention, the first covering insulating layer has an opening that is opened so as to surround the second region, and the second covering insulating layer includes the opening. It is formed in a part.

  With this configuration, the second covering insulating layer can be easily and highly accurately formed in the second region, and a highly reliable printed wiring board that suppresses the influence of the surrounding environment can be manufactured with high productivity. it can.

  In the printed wiring board manufacturing method according to the present invention, the air-containing insulating layer is formed by containing hollow microcapsules that enclose air.

  With this configuration, an air-containing insulating layer containing air can be formed easily and with high accuracy.

  Moreover, in the printed wiring board manufacturing method which concerns on this invention, the said hollow microcapsule is filled into the said opening part via a filler.

  With this configuration, the hollow microcapsules can be easily and accurately filled into the air-containing insulating layer.

  In the printed wiring board manufacturing method according to the present invention, the filler is a paste-like substance or a liquid substance.

  With this configuration, the filling material can be easily and accurately filled into the opening.

  In the printed wiring board manufacturing method according to the present invention, the filler is cured or semi-cured after filling the opening.

  With this configuration, it is possible to improve the stability of the filling material and obtain a highly reliable printed wiring board.

  In the printed wiring board manufacturing method according to the present invention, the second covering insulating layer forming step is performed by applying a printing technique.

  With this configuration, the second covering insulating layer forming step can be performed easily and with high accuracy, and the printed wiring board 1 can be manufactured with high productivity.

  In the printed wiring board manufacturing method according to the present invention, the filler is a powder material.

  With this configuration, the filling material can be easily and accurately filled into the opening.

  In the printed wiring board manufacturing method according to the present invention, the filler is melted and re-solidified after filling the opening.

  With this configuration, it is possible to improve the stability of the filling material and obtain a highly reliable printed wiring board.

  An electronic device according to the present invention is an electronic device equipped with a printed wiring board, and the printed wiring board is a printed wiring board according to the present invention.

  With this configuration, it is possible to provide a highly reliable electronic device that is not easily affected by external temperature and humidity changes, and that can perform high-speed transmission.

  According to the printed wiring board according to the present invention, a printed wiring board having a base insulating layer, a circuit pattern formed by patterning a conductor layer laminated on the base insulating layer, and a covering insulating layer covering the circuit pattern The covering insulating layer includes a first covering insulating layer that covers the first region of the circuit pattern, and a second covering insulating layer that covers the second region of the circuit pattern. Since it is formed of an air-containing insulating layer containing air, it is possible to suppress the influence of external temperature and humidity changes on the second area, and condensation and heat in the second area due to external temperature and humidity changes. Since it is possible to prevent expansion, etc., it is possible to perform high-speed transmission by preventing deterioration of electrical characteristics such as a decrease in insulation resistance in the second region, or performance deterioration such as blistering, peeling between layers, and corrosion. wiring An effect that can be.

  According to the printed wiring board manufacturing method of the present invention, the base insulating layer, the circuit pattern formed by patterning the conductor layer laminated on the base insulating layer, and the covering insulating layer covering the circuit pattern are provided. A printed wiring board manufacturing method for manufacturing a printed wiring board having a circuit pattern forming step of forming a circuit pattern by patterning a conductor layer laminated on a base insulating layer, and a first method of covering a first region of the circuit pattern A first covering insulating layer forming step for forming one covering insulating layer; and a second covering insulating layer forming step for forming a second covering insulating layer for covering the second region of the circuit pattern. Since it is formed of an air-containing insulating layer containing air, the second region of the circuit pattern is covered with the air-containing insulating layer to suppress the influence of external temperature and humidity changes on the second region. The possible printed circuit board is advantageously possible to manufacture easily and with good productivity.

  The electronic device according to the present invention is an electronic device equipped with a printed wiring board, and the printed wiring board is a printed wiring board according to the present invention, so that it is affected by external temperature and humidity changes. It is difficult to achieve a highly reliable electronic device capable of high-speed transmission.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<Embodiment 1>
A printed wiring board according to the present embodiment will be described with reference to FIG.

  FIG. 1 is a perspective view showing a printed wiring board according to Embodiment 1 of the present invention.

  In the printed wiring board 1 according to the present embodiment, for example, a multi-layer part 1m in which a conductor layer (circuit pattern) has a four-layer structure (multi-layer structure), and a single-layer conductor layer derived from the multi-layer part 1m include a transmission line. And a terminal portion 1t exposed at the tip of the cable portion 1cab. Further, a connecting portion 1c that interconnects the multilayer portion 1m and the cable portion 1cab is disposed between the two. In addition, the function as a transmission path is calculated | required also with respect to the connection part 1c.

  The printed wiring board 1 according to the present embodiment is called a so-called flex-rigid wiring board. The multilayer part 1m constitutes a rigid part, and the cable part 1cab constitutes a flex part. When the printed wiring board 1 has a function corresponding to high-speed processing, for example, high-speed processing (high-speed transmission) is also required for the connection portion 1c and the cable portion 1cab.

  In the printed wiring board 1 according to the present embodiment, an air-containing insulating layer containing air is applied to the insulating layer that covers the conductor layer (circuit pattern / conductor pattern) with respect to the connecting portion 1c and the cable portion 1cab.

  Therefore, the printed wiring board 1 can suppress the influence of the external temperature and humidity change on the connection portion 1c and the cable portion 1cab, and the dew condensation on the connection portion 1c and the cable portion 1cab due to the external temperature and humidity change. Since it is possible to prevent thermal expansion and the like, it is possible to prevent a decrease in electrical characteristics such as a decrease in insulation resistance in the connection portion 1c and the cable portion 1cab. That is, a high-speed transmission function can be realized.

  The specific configuration of the air-containing insulating layer and the printed wiring board 1 to which the air-containing insulating layer is applied will be described in detail in the second and subsequent embodiments.

<Embodiment 2>
Based on FIG. 2 thru | or FIG. 8, the printed wiring board and printed wiring board manufacturing method which concern on this Embodiment are demonstrated. The basic configuration is the same as that of the printed wiring board 1 of the first embodiment.

  FIG. 2 is a cross-sectional view showing a state of the base insulating layer provided with the conductor layer of the printed wiring board according to Embodiment 2 of the present invention.

  The printed wiring board 1 according to the present embodiment includes a base insulating layer 10 and a conductor layer 20 laminated on both surfaces of the base insulating layer 10 as a starting material. That is, the starting material of the printed wiring board 1 according to the present embodiment is composed of a double-sided flexible wiring board. The base insulating layer 10 and the conductor layer 20 constitute, for example, an inner layer core having a four-layer structure. Moreover, a transmission path (cable part) is comprised so that it may mention later.

  For example, a polyimide resin film, a liquid crystal polymer film, or the like can be applied to the base insulating layer 10. Therefore, the printed wiring board 1 with high productivity and high reliability can be configured. When the liquid crystal polymer film is applied, the relative dielectric constant and the dielectric loss tangent are small as compared with the case where the polyimide resin film is applied, and it is possible to improve the electrical characteristics with respect to the high frequency.

  Moreover, as the conductor layer 20, a general copper foil was applied. That is, as the starting material of the printed wiring board 1 according to the present embodiment, a commercially available double-sided flexible wiring material can be applied as it is.

  FIG. 3 is a cross-sectional view showing a state in which the circuit pattern of the printed wiring board according to Embodiment 2 of the present invention is formed.

  A circuit pattern 21 (first area 21f, second area 21s, circuit pattern 21r) is formed by applying a known technique to the conductor layer 20 (circuit pattern forming step). That is, the circuit pattern 21 on the surface of the base insulating layer 10 is formed by being divided into the first region 21f and the second region 21s.

  The first region 21f corresponds to the multilayer portion 1m shown in the first embodiment, and the second region 21s corresponds to the connection portion 1c, the cable portion 1cab, and the terminal portion 1t shown in the first embodiment. . That is, the second region 21s is extended (formed) as a region to which the high-speed transmission described in the first embodiment is applied (transmission path: connection portion 1c, cable portion 1cab, terminal portion 1t). The first region 21f is formed as a region constituting a multilayer structure.

  Further, a circuit pattern 21r constituting a multilayer structure is formed on the back surface of the base insulating layer 10. In the present embodiment, descriptions of via holes and through holes are omitted. However, if necessary, they can be processed in an appropriate process.

  FIG. 4 is an explanatory view showing a state in which a first covering insulating layer covering the first region of the circuit pattern of the printed wiring board according to Embodiment 2 of the present invention is formed, (A) is a perspective view, (B) is sectional drawing which shows the cross section in the arrow BB of (A).

  After the circuit pattern 21 is formed, a first covering insulating layer 30f (covering insulating layer 30) that covers the first region 21f of the circuit pattern 21 is formed (first covering insulating layer forming step). That is, the first covering insulating layer 30f is formed in a region (first region 21f) excluding the second region 21s of the circuit pattern 21 where high-speed transmission is required.

  In the present embodiment, the first covering insulating layer 30f is formed, for example, by punching and bonding a polyimide film or a liquid crystal polymer film with an adhesive that is commercially available for a coverlay film or the like into a required shape. .

  The first covering insulating layer 30 f is basically necessary for the outer peripheral portion of the printed wiring board 1 in order to protect the circuit pattern 21. Therefore, the first covering insulating layer 30f (covering insulating layer 30) is also formed on the outer peripheral region (edge region) of the second region 21s.

  That is, the first covering insulating layer 30f covers the wiring pattern 21f, and further extends so as to surround the second region 21s, and constitutes an opening 30fw opened so as to surround the second region 21s. .

  The terminal portion 21st is a portion that needs to be exposed in the final product (completed printed wiring board 1). Therefore, the first covering insulating layer 30f (covering insulating layer 30) is not formed in the region of the terminal portion 21st. Note that the first covering insulating layer 30f becomes a part of the interlayer insulating layer because the conductor layer is further laminated in the subsequent steps.

  The thickness of the first covering insulating layer 30f is formed to be equal to the thickness of the second covering insulating layer 30s (air-containing insulating layer) formed in a later step. Moreover, since it has a great influence on the flexibility of the printed wiring board 1, it is determined according to the required performance such as flexibility. In this embodiment, it is formed to have a thickness between 0.025 mm and 0.1 mm.

  FIG. 5 is a cross-sectional view showing a state in which the second covering insulating layer is formed in the opening formed in the first covering insulating layer covering the circuit pattern of the printed wiring board according to Embodiment 2 of the present invention.

  After forming the first covering insulating layer 30f, the second covering insulating layer 30s covering the second region 21s of the circuit pattern 21 is formed (second covering insulating layer forming step). That is, the second covering insulating layer 30 s is formed in a form that fills the opening 30 fw of the first covering insulating layer 30 f formed in the first region 21 f of the circuit pattern 21.

  Since the second covering insulating layer 30 s is formed in a form in which the opening 30 fw is filled (print filling) by applying a printing technique, it can be easily formed with high accuracy.

  The second covering insulating layer 30s is formed of an air-containing insulating layer containing air. Therefore, the printed wiring board 1 can suppress the influence of external temperature and humidity changes on the second area 21s, and prevents condensation, thermal expansion, and the like in the second area 21s due to external temperature and humidity changes. Therefore, it is possible to prevent a decrease in electrical characteristics such as a decrease in insulation resistance in the second region 21s.

  The first covering insulating layer 30 f and the second covering insulating layer 30 s constitute the covering insulating layer 30 that covers the circuit pattern 21.

  FIG. 6 is an explanatory view conceptually showing the structure of the second covering insulating layer of the printed wiring board according to Embodiment 2 of the present invention. FIG. 6A shows the second covering insulating layer formed of hollow microcapsules. Sectional drawing which shows a case, (B) is sectional drawing which shows the case where the 2nd coating insulation layer is formed with a hollow microcapsule and a filler.

  The second covering insulating layer 30s (air-containing insulating layer) is configured to contain hollow microcapsules 31 that enclose air (bubbles 31b). Therefore, the air-containing insulating layer containing air (second covering insulating layer 30s) can be formed easily and with high accuracy.

  The hollow microcapsule 31 has a structure in which the bubbles 31b are wrapped with the shell portion 31c. Accordingly, since the air is arranged inside the hollow microcapsule 31, it is possible to suppress the change in the outside air temperature and the temperature change during mounting from being transmitted to the second region 21s (circuit pattern 21). .

  That is, by including the hollow microcapsule 31 in the second covering insulating layer 30s, the circuit pattern 21 in the second region 21s can be kept airtight from the outside. Therefore, dew condensation accompanying temperature / humidity change of the outside air, and the accompanying decrease in insulation resistance and migration are prevented to suppress the change in electrical characteristics, and the swelling around the second region 21s (circuit pattern 21) is suppressed. Is possible.

  The second covering insulating layer 30s can be configured by only the hollow microcapsules 31 (FIG. 1A).

  Further, the hollow microcapsule 31 can be filled into the opening 30 fw via the filler 32 ((B) in the same figure). By using the filler 32, the hollow microcapsule 31 can be easily and accurately filled into the opening 30fw.

  As the hollow microcapsule 31, a resin made of polyethylene, polystyrene, polystyrene, polyacrylic acid, polymethacrylic acid or the like, or an inorganic material such as calcium carbonate or magnesium carbonate as a shell can be used. The diameter of the hollow microcapsule 31 is set to several μm to several tens μm in consideration of the balance with the thickness of the opening 30 fw. The material and diameter of the shell can be selected according to the required performance such as the required transmission signal frequency and performance and the flexibility of the flexible wiring section.

  When the filler 32 is applied in addition to the hollow microcapsule 31, the filler 32 can be a paste-like substance, a liquid substance, a powder, a fine powder, or the like as a base material. That is, the second covering insulating layer 30 s is filled by mixing (kneading) the base material and the hollow microcapsule 31. By applying the filler 32, it becomes possible to improve workability, and handling in the subsequent processing steps can be performed easily and with high accuracy.

  As the paste-like substance or the liquid substance, for example, a resin such as polyethylene, polystyrene, polystyrene or the like that is liquid or semi-cured to be pasty can be used. Further, by applying a paste-like substance or a liquid substance as the filler 32, the second covering insulating layer forming step can be performed by applying a printing technique. By applying the printing technique, the second covering insulating layer forming step can be easily and accurately performed, and the printed wiring board 1 can be manufactured with high productivity.

  In the case where the second covering insulating layer 30s is filled and formed by applying a paste-like substance or a liquid substance, the filling 32 is cured or semi-cured after filling the opening 30fw. Therefore, it is possible to improve the stability of the filler 32 and to obtain a highly reliable printed wiring board 1.

  When powder (fine powder) is applied, the diameter of the powder is smaller than the diameter of the hollow microcapsule 31. As the powder (fine powder), for example, resins such as polyethylene, polystyrene, and polystyrene, various fats and oils (for example, pine oil and pine), petrolatum, gelatin, and the like can be applied. Moreover, it is possible to apply not only resins but also fine powders of inorganic materials such as silica alumina, aluminum hydroxide, talc, calcium carbonate and magnesium carbonate.

  By using the filling material 32 as a powder substance, the filling material 32 can be easily and accurately filled into the opening 30fw. Further, the filling 32 is melted and re-solidified after filling the opening 30fw. Therefore, it is possible to improve the stability of the filler 32 and to obtain a highly reliable printed wiring board 1.

  When the low melting point resin powder is used, the powder may be once melted and then solidified again to efficiently fill the gaps between the hollow microcapsules 31.

  By filling the hollow microcapsule 31 into the opening 30 fw via the filler 32, the efficiency of the filling operation and the like can be improved. In addition, it is possible to fill the voids generated between the hollow microcapsules 31 with the filler 32.

  That is, by filling the filler 32 between the hollow microcapsules 31, the air remaining between the hollow microcapsules 31 expands due to a temperature rise or the like, or the adhesion strength between layers decreases. It is possible to prevent the moisture in the air remaining in the air gap from condensing at a low temperature and reducing the insulation.

  In addition, when the softness | flexibility of the printed wiring board 1 is impaired by hardening of a filler 32, semi-hardening, and melt | dissolution solidification, the fall of high-speed transmission performance may occur. Therefore, it is necessary to select a material for the filler 32 in consideration of the influence of post-processing and necessary functional specifications.

  FIG. 7 is an explanatory view showing a state in which a protective insulating layer for protecting the second covering insulating layer of the printed wiring board according to Embodiment 2 of the present invention is formed, and (A) shows the first covering insulating layer and the first covering insulating layer. 2 is a cross-sectional view when a protective insulating layer is formed on both of the covering insulating layers, (B) is a perspective view of (A), and (C) is a protective insulating layer formed on the second covering insulating layer. It is a perspective view which shows the case where it did.

  A protective insulating layer 40 serving as a cover lay for protecting the surface is formed on the covering insulating layer 30 (the first covering insulating layer 30f and the second covering insulating layer 30s). The protective insulating layer 40 is formed so as to cover and protect at least the second covering insulating layer 30s ((C) in the figure). It is possible to protect the surface of the second covering insulating layer 30s and improve the reliability of the second covering insulating layer 30s.

  The protective insulating layer 40 can also be formed in the region where the first covering insulating layer 30f is formed (FIGS. 4A and 4B).

  A commercially available coverlay material can be applied to the protective insulating layer 40. By forming the protective insulating layer 40, the second covering insulating layer 30s (air-containing insulating layer) is in a sealed state. Note that the protective insulating layer 40 can be formed of a polyimide resin film or a liquid crystal polymer film, like the first covering insulating layer 30f. Therefore, the printed wiring board 1 with high productivity and high reliability can be configured.

  As described above, the printed wiring board 1 according to the present embodiment covers the base insulating layer 10, the circuit pattern 21 formed by patterning the conductor layer 20 laminated on the base insulating layer 10, and the circuit pattern 21. And a covering insulating layer 30.

  The covering insulating layer 30 includes a first covering insulating layer 30f that covers the first region 21f of the circuit pattern 21, and a second covering insulating layer 30s that covers the second region 21s of the circuit pattern 21. The covering insulating layer 30s is formed of an air-containing insulating layer containing air.

  Therefore, it is possible to suppress the influence of external temperature and humidity changes on the second region 21s, and it is possible to prevent condensation and thermal expansion in the second region 21s due to external temperature and humidity changes. Thus, the printed wiring board 1 capable of high-speed transmission can be obtained by preventing deterioration in electrical characteristics such as a decrease in insulation resistance in the second region 21s, or deterioration in performance such as blistering, interlayer peeling, and corrosion.

  Further, the second covering insulating layer 30s (air-containing insulating layer) contains hollow microcapsules 31 that enclose air. Therefore, an air-containing insulating layer containing air can be easily configured.

  Further, the second covering insulating layer 30 s (air-containing insulating layer) contains a filler 32 that fills the space between the hollow microcapsules 31. Therefore, the formation and processing of the air-containing insulating layer can be facilitated, and the gap between the hollow microcapsules 31 can be filled to eliminate the unnecessary action of air existing between the hollow microcapsules 31 to improve the reliability. It becomes possible.

  The second region 21s is extended to serve as a transmission line. Therefore, the printed wiring board 1 having a transmission path (cable portion) in which the influence of the surrounding environment is suppressed can be obtained.

  The first covering insulating layer 30f is extended so as to surround the second region 21s, and has an opening 30fw opened so as to surround the second region 21s. The second covering insulating layer 30s includes The opening 30fw is formed (filled). Therefore, the second covering insulating layer 30s can be formed easily and with high accuracy, and the printed wiring board 1 having the highly reliable second covering insulating layer 30s can be obtained.

  The base insulating layer 10, the first covering insulating layer 30f, and the protective insulating layer 40 are formed of a polyimide resin film or a liquid crystal polymer film. Therefore, the printed wiring board 1 with high productivity and high reliability can be configured.

  In addition, as described above, the printed wiring board manufacturing method according to the present embodiment includes the base insulating layer 10, the circuit pattern 21 formed by patterning the conductor layer 20 laminated on the base insulating layer 10, and the circuit pattern. The printed wiring board 1 having the covering insulating layer 30 that covers 21 is manufactured.

  In addition, the printed wiring board manufacturing method according to the present embodiment includes a circuit pattern forming step of forming the circuit pattern 21 by patterning the conductor layer 20 laminated on the base insulating layer 10, and the first region 21f of the circuit pattern 21. A first covering insulating layer forming step for forming the first covering insulating layer 30f for covering the second pattern insulating layer, and a second covering insulating layer forming step for forming the second covering insulating layer 30s for covering the second region 21s of the circuit pattern 21. The second covering insulating layer 30s is formed of an air-containing insulating layer containing air.

  Therefore, the printed wiring board 1 capable of covering the second region 21s of the circuit pattern 21 with the air-containing insulating layer and suppressing the influence of external temperature and humidity changes on the second region 21s can be easily manufactured with high productivity. can do.

  Further, the first covering insulating layer 30f has an opening 30fw opened so as to surround the second region 21s, and the second covering insulating layer 30s is formed by filling the opening 30fw.

  Therefore, the second covering insulating layer 30s can be easily and highly accurately formed in the second region 21s, and the highly reliable printed wiring board 1 that suppresses the influence of the surrounding environment is manufactured with high productivity. Can do.

  FIG. 8 is a cross-sectional view showing the state of the multilayer structure in the first region after forming the protective insulating layer of the printed wiring board according to Embodiment 2 of the present invention.

  After the formation of the protective insulating layer 40, the multilayer insulating layer 50 and the multilayer circuit pattern 60 are formed in the first region 21f in the same manner as in the conventional publicly known technique, and the multilayer portion 1m is formed. In addition, the printed wiring board 1 is completed through surface solder resist formation, symbol formation, other surface treatment, and outline processing. Since these steps are the same as those in the prior art, description thereof is omitted.

<Embodiment 3>
An electronic apparatus (not shown) according to the present embodiment is mounted with printed wiring board 1 according to the first and second embodiments. Therefore, it is possible to provide a highly reliable electronic device that is not easily affected by external temperature and humidity changes, can perform high-speed transmission.

  Electronic devices are, for example, portable information terminals that require a small volume and high speed and are used in a wide temperature and humidity range and in harsh environments.

It is a perspective view which shows the printed wiring board which concerns on Embodiment 1 of this invention. It is sectional drawing which shows the state of the base | substrate insulating layer provided with the conductor layer of the printed wiring board which concerns on Embodiment 2 of this invention. It is sectional drawing which shows the state in which the circuit pattern of the printed wiring board which concerns on Embodiment 2 of this invention was formed. It is explanatory drawing which shows the state in which the 1st coating insulating layer which coat | covers the 1st area | region of the circuit pattern of the printed wiring board which concerns on Embodiment 2 of this invention was formed, (A) is a perspective view, (B) is ( It is sectional drawing which shows the cross section in the arrow BB of A). It is sectional drawing which shows the state which formed the 2nd coating insulation layer in the opening part formed in the 1st coating insulation layer which coat | covers the circuit pattern of the printed wiring board which concerns on Embodiment 2 of this invention. It is explanatory drawing which shows notionally the structure of the 2nd coating insulation layer of the printed wiring board concerning Embodiment 2 of this invention, (A) is a cross section which shows the case where a 2nd coating insulation layer is formed with a hollow microcapsule. FIG. 4B is a cross-sectional view showing a case where the second covering insulating layer is formed with hollow microcapsules and fillers. It is explanatory drawing which shows the state which formed the protective insulating layer which protects the 2nd coating insulating layer of the printed wiring board which concerns on Embodiment 2 of this invention, (A) is a 1st coating insulating layer and a 2nd coating insulating layer Sectional drawing at the time of forming a protective insulating layer with respect to both, (B) is a perspective view in the case of (A), (C) shows the case where a protective insulating layer is formed on the second covering insulating layer. It is a perspective view. It is sectional drawing which shows the state of the multilayer structure in the 1st area | region after forming the protective insulating layer of the printed wiring board which concerns on Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Printed wiring board 1c Connection part 1cab Cable part 1m Multilayer part 1t Terminal part 10 Underlying insulating layer 20 Conductor layer 21 Circuit pattern 21f 1st area | region 21r Circuit pattern 21s 2nd area | region (transmission path)
21st terminal portion 30 covering insulating layer 30f first covering insulating layer 30fw opening 30s second covering insulating layer (air-containing insulating layer)
31 hollow microcapsule 31b bubble 31c shell 32 filling 40 protective insulating layer 50 laminated insulating layer 60 laminated circuit pattern

Claims (17)

A printed wiring board having a base insulating layer, a circuit pattern formed by patterning a conductor layer laminated on the base insulating layer, and a covering insulating layer covering the circuit pattern,
The covering insulating layer includes a first covering insulating layer that covers a first region of the circuit pattern, and a second covering insulating layer that covers a second region of the circuit pattern,
The printed wiring board, wherein the second covering insulating layer is formed of an air-containing insulating layer containing air. The printed wiring board according to claim 1,
The printed wiring board, wherein the air-containing insulating layer contains hollow microcapsules enclosing air. The printed wiring board according to claim 2,
The printed wiring board, wherein the air-containing insulating layer contains a filler that fills a space between the hollow microcapsules. The printed wiring board according to any one of claims 1 to 3,
The printed wiring board, wherein the second region is extended to serve as a transmission line. The printed wiring board according to claim 1, wherein:
The first covering insulating layer has an opening which is opened so as to surround the periphery of the second region, and the second covering insulating layer is formed in the opening. Board. The printed wiring board according to any one of claims 1 to 5,
A printed wiring board comprising a protective insulating layer that covers and protects the second covering insulating layer. The printed wiring board according to claim 6,
The printed wiring board, wherein the base insulating layer, the first covering insulating layer, and the protective insulating layer are formed of a polyimide resin film or a liquid crystal polymer film. A printed wiring board manufacturing method for manufacturing a printed wiring board having a base insulating layer, a circuit pattern formed by patterning a conductor layer laminated on the base insulating layer, and a covering insulating layer covering the circuit pattern There,
A circuit pattern forming step of forming a circuit pattern by patterning the conductor layer laminated on the base insulating layer;
A first covering insulating layer forming step of forming a first covering insulating layer covering the first region of the circuit pattern;
A second covering insulating layer forming step of forming a second covering insulating layer covering the second region of the circuit pattern,
The method for manufacturing a printed wiring board, wherein the second covering insulating layer is formed of an air-containing insulating layer containing air. It is a printed wiring board manufacturing method of Claim 8, Comprising:
The printed circuit board according to claim 1, wherein the first covering insulating layer has an opening that is opened so as to surround the second region, and the second covering insulating layer is formed in the opening. Production method. It is a printed wiring board manufacturing method of Claim 8 or Claim 9,
The method for producing a printed wiring board, wherein the air-containing insulating layer is formed by containing hollow microcapsules enclosing air. It is a printed wiring board manufacturing method according to claim 10,
The said hollow microcapsule is filled in the said opening part through a filling material. The printed wiring board manufacturing method characterized by the above-mentioned. It is a printed wiring board manufacturing method of Claim 11, Comprising:
The printed wiring board manufacturing method, wherein the filling is a paste-like substance or a liquid substance. It is a printed wiring board manufacturing method of Claim 12, Comprising:
The filling material is cured or semi-cured after being filled in the opening, The printed wiring board manufacturing method, wherein: It is a printed wiring board manufacturing method as described in any one of Claims 8 thru | or 13, Comprising:
The method for producing a printed wiring board, wherein the second covering insulating layer forming step is performed by applying a printing technique. It is a printed wiring board manufacturing method of Claim 11, Comprising:
The printed wiring board manufacturing method, wherein the filler is a powder substance. The printed wiring board manufacturing method according to claim 15,
The filling material is melted and re-solidified after the opening is filled in the printed wiring board manufacturing method. An electronic device equipped with a printed wiring board,
An electronic device, wherein the printed wiring board is the printed wiring board according to any one of claims 1 to 7.

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