JP2004356588A - Material processing method by ultrashort pulse laser, printed circuit board and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stable processing method of a recessed portion by which accuracy of a submicron order is easily obtained without using a complicated processing process such as a lithography process. <P>SOLUTION: In the material processing method by an ultrashort pulse laser, a femtosecond laser 12 is irradiated to a substrate 3 formed by an insulating material 1, and the recessed portion 13 is formed for embedding and forming an electronic element 5 on the substrate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a processing technique for forming a recess for embedding an electronic element in a substrate formed of various materials, and particularly by an ultrashort pulse laser using a femtosecond laser. The present invention relates to a material processing method, a printed wiring board manufacturing method using the material processing method using an ultrashort pulse laser, and a printed wiring board manufactured by the printed wiring board manufacturing method.
[0002]
[Prior art]
In recent years, with the progress of miniaturization of electronic circuits, most electronic components have been surface-mounted. Passive electronic elements such as resistors, capacitors, and inductors have been made into chips, and are continuing to become smaller. On the other hand, various passive electronic elements have been mounted on a substrate of a multilayer printed wiring board using an organic material as a base material by printing, embedding, and embedding.
[0003]
In order to fabricate or embed these passive electronic elements in the printed circuit board substrate, a three-dimensional fine recess for embedding or embedding these passive electronic elements in the substrate. Must be formed by processing. In order to form the recesses on the substrate, a lithography (photographic etching) process is usually used.
[0004]
In this lithography process, a series of processes such as resist coating, resist pattern formation exposure, resist development, pattern etching, resist stripping, and the like are performed in a layer in which a plurality of material films are stacked and a three-dimensional recess is processed.
[0005]
FIG. 11 shows a conventional manufacturing method of a printed wiring board in which a resistor constituting an electronic element is embedded.
[0006]
First, a copper-clad substrate 3 in which a copper foil 2 having a thickness of about 10 μm is pasted on a base material 1 made of a composite material such as glass epoxy and having a thickness of about 0.5 mm to several mm is created (FIG. 11A). ). Next, a photosensitive resist 4 is applied to the surface of the copper foil 2 of the copper-clad substrate 3 (FIG. 11B), and then a pattern exposure of a wiring pattern (electronic circuit) is performed on the resist 4 (FIG. 11). (C)) and development (FIG. 11D) are sequentially performed.
[0007]
Subsequently, the copper foil 2 is removed by etching in accordance with the exposure pattern to form a wiring pattern (electronic circuit) (not shown) (FIG. 11E). After the etching is completed, the resist 4 is peeled off with a solvent to expose the wiring pattern (FIG. 11 (f)).
[0008]
The resistor 5 is applied by screen printing or the like so that both ends of the resistor 5 cover the wiring pattern (electronic circuit) of the copper foil 2 (FIG. 11G). The applied resistor 5 is subjected to solidification processing such as low-temperature firing (not shown), and then the resistor 5 is irradiated with laser using a YAG laser 6 so that the resistance value of the resistor 5 is a design allowable value. The resistor 5 is trimmed so as to be inside (FIG. 11 (h)). Finally, an insulating film 7 is formed by a lamination or coating process so as to cover the upper surface of the resistor 5 (FIG. 11 (i)).
In this manner, a printed wiring board having the resistor 5 embedded therein is manufactured.
[0009]
Next, FIGS. 12 and 13 show a conventional method for manufacturing a printed wiring board in which a dielectric (capacitor) is embedded as an electronic element.
[0010]
Similarly to FIG. 11, a copper-clad substrate 3 is prepared in which a copper foil 2 b having a thickness of about 10 μm is attached to a base material 1 made of a composite material such as glass epoxy and having a thickness of about 0.5 mm to several mm (see FIG. 11). 12 (a)). Next, a photosensitive resist 4 is formed on the surface of the copper foil 2b by a dry film resist lamination (DFR lamination) method (FIG. 12B), and then pattern exposure of the wiring pattern (electronic circuit) including the lower electrode is performed. (FIG. 12C) and development is performed (FIG. 12D).
[0011]
Subsequently, the wiring pattern (electronic circuit) of the lower electrode 8b of the dielectric (capacitor) is formed by removing the copper foil 2b in accordance with the exposure pattern by etching (FIG. 12E). After the etching is completed, the resist 4 is peeled off with a solvent to expose the wiring pattern of the lower electrode 8b (FIG. 12 (f)).
[0012]
Next, the insulating resin 9 is pasted on the upper surface of the wiring pattern of the lower electrode 8b by a dry film resist laminate (DER) method (FIG. 12G). Thereafter, lithography processes such as resist coating, pattern exposure, development, etching, and resist removal are repeated (FIG. 12 (h)) to form a three-dimensional recess (filling groove) 10 (FIG. 12 (i)). Then, the dielectric 11 is applied and filled into the formed recess (filling groove) 10 (FIG. 13 (j)). Although not shown, the surface of the dielectric 11 may be smoothed thereafter.
[0013]
After the dielectric 11 is applied and filled into the recess (filling groove) 10, the copper foil 2b is formed by electroless plating (FIG. 13 (k)). Thereafter, dry film resist lamination (DFR), exposure, development, etching, and resist stripping are sequentially performed again by lithography (FIGS. 13 (l), (m), (n), and (o)). An upper electrode 8 a is formed on the dielectric 11.
[0014]
After that, the upper electrode 8a is irradiated with laser using the YAG laser 6, and the upper electrode 8a is trimmed so that the capacitance value between the electrodes 8a and 8b of the dielectric 11 is within the design allowable value (see FIG. 13 (p)).
[0015]
In this manner, a printed wiring board having the dielectric 11 embedded therein is manufactured.
[0016]
[Patent Document 1]
JP 2001-239379 A
[0017]
[Non-Patent Document 1]
Katsumi Midorikawa, “Femtosecond laser interaction with matter”, Journal of Laser Processing Vol. 8, no. 3 (2001)
[0018]
[Problems to be solved by the invention]
However, the processing accuracy for the substrate and other members in the lithography process including the above-described resist coating, pattern exposure, development, etching processing, resist stripping, and the like is generally about 2 μm.
[0019]
In the printed wiring board in which the dielectric 11 shown in FIGS. 12 and 13 is embedded, the dimensional variation of the recess (filling groove) 10 formed in FIG. Therefore, it is necessary to perform trimming by irradiating the upper electrode 8a with a laser so that the capacitance value between the electrodes 8a and 8b of the dielectric 11 is within the design allowable value.
[0020]
In the printed wiring board in which the resistor 5 shown in FIG. 11 is embedded, as shown in FIG. 11 (f), the resistor 5 is made of copper foil 2 at both ends by screen printing or the like. It is applied so as to cover the wiring pattern (electronic circuit). Therefore, the resistance value variation of 20% or more occurs. For this reason, there is a problem that a trimming step shown in FIG.
[0021]
In order to obtain a manufacturing method that does not perform trimming, it is necessary to perform sub-micron microfabrication on the resistor 5 and the recess (filling groove) 10. However, in the conventional machining process as described above, the machining conditions are managed. Severity, complexity of equipment and its scale become enormous, and the processing cost increases rapidly as the yield decreases.
[0022]
The present invention has been made paying attention to the problems of the conventional technology as described above, and has a high processing accuracy easily and without using a complicated processing process such as a lithography process, A material processing method using an ultrashort pulse laser using a femtosecond laser capable of simplifying the manufacturing method without the need to adjust the characteristic values of the embedded electronic device, and a material processing method using the ultrashort pulse laser An object of the present invention is to provide a method for producing a printed wiring board using the above and a printed wiring board produced by the method for producing a printed wiring board.
[0023]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the invention of claim 1 irradiates a femtosecond laser to a substrate formed of an insulating material, and forms a recess for embedding an electronic element in the substrate. Is a material processing method using an ultrashort pulse laser.
[0024]
According to the second aspect of the present invention, a substrate formed of a composite material in which an inorganic material is mixed with an organic material is irradiated with a femtosecond laser to form a recess for embedding an electronic element in the substrate. This is a material processing method using an ultrashort pulse laser.
[0025]
According to a third aspect of the present invention, a substrate on which a metal layer and an insulating material layer are laminated is irradiated with a femtosecond laser to form a recess for embedding an electronic element in the substrate. This is a material processing method using an ultrashort pulse laser.
[0026]
According to the fourth aspect of the present invention, a substrate in which a composite material layer in which an inorganic material is mixed with an organic material and a metal layer are irradiated with a femtosecond laser to embed an electronic device in the substrate. A material processing method using an ultrashort pulse laser.
[0027]
In this first to fourth aspects, by using a femtosecond laser, it is possible to form a recess having a sub-μm dimensional accuracy for embedding an electronic element in a substrate. Further, it is not necessary to select a laser light source (wavelength) that matches the light absorption characteristics of the material. Therefore, a recess having excellent processing characteristics can be formed on a substrate formed of various materials.
[0028]
According to a fifth aspect of the present invention, in the material processing method using the ultrashort pulse laser according to any one of the first to fourth aspects, the electronic element is any one of a resistor, a capacitor, and an inductor.
[0029]
The invention of claim 6 is the material processing method using the ultrashort pulse laser according to any one of claims 1 to 5, wherein the depth of the recess to be processed is the processing depth relative to the irradiation energy amount of the femtosecond laser. Within the threshold region in the depth direction in the characteristics.
[0030]
According to the sixth aspect of the present invention, even when the irradiation energy amount of the femtosecond laser fluctuates, the depth of the recess to be processed hardly fluctuates and high processing accuracy is maintained.
[0031]
The invention of claim 7 irradiates a femtosecond laser to one surface of a substrate formed of an insulating material to form a recess in the substrate, and fills the formed recess with a material for an electronic device. Thus, an electronic element is embedded in the recess, and a metal layer having an electronic circuit including an electrode for the electronic element is formed on one surface of the substrate on which the electronic element is embedded. It is a manufacturing method of a printed wiring board.
[0032]
According to an eighth aspect of the present invention, an electronic circuit including an electrode for an electronic element is formed on a metal layer of a substrate in which an insulating material layer and a metal layer are laminated, and an insulating film layer is formed on the upper surface of the metal layer of the substrate. A side surface of the insulating film layer of the substrate on which the film layer is formed is irradiated with a femtosecond laser to form a recess reaching the electronic circuit on the substrate, and the material of the electronic element is filled in the formed recess. Thus, a printed wiring board manufacturing method is characterized in that an electronic element is embedded in a recess.
[0033]
According to the seventh and eighth aspects, since the concave portion is formed on the processing object such as the substrate using the femtosecond laser, the manufacturing process is simplified without using a complicated processing process such as a lithography process. it can.
[0034]
The invention according to claim 9 is a printed wiring board manufactured by the method for manufacturing a printed wiring board according to claim 7 or 8.
[0035]
DETAILED DESCRIPTION OF THE INVENTION
First, a feature of forming a recess using a femtosecond laser on a processing target such as a substrate formed of various insulating materials such as an organic material such as a resin or a ceramic substrate will be described.
[0036]
The insulating material described in the present invention generally refers to a substrate of a printed wiring board or an insulating material used as a part of the substrate material, specifically, an inorganic material such as ceramic or glass, epoxy, An organic material containing a resin such as polyimide, liquid crystal polymer, paper phenol, or a composite material composed of an organic material such as glass epoxy and an inorganic material.
[0037]
As shown in FIG. 7, the femtosecond laser has an on-time (pulse width) shorter than the thermal relaxation time. ^-12 It is an ultrashort pulse laser set to a second (1 picosecond) or less. By the way, the pulse width of normal YAG laser (reference wave YAG laser) is 10 ^-3 The pulse width of the high frequency YAG laser is about 10 seconds. ^-6 About seconds.
[0038]
In recent years, it has been proposed to use a femtosecond laser having a pulse width of 1 picosecond or less according to the present invention for processing that requires high depth accuracy for an organic compound. FIG. 7 is a characteristic diagram showing the relationship between the laser pulse width and the thermal diffusion length in the processed material resulting from laser irradiation. As can be understood from this characteristic diagram, in the femtosecond laser, non-thermal processing is possible due to a phenomenon that is shorter than multiphoton absorption and thermal relaxation time. Furthermore, the processing resolution is below the diffraction limit of light due to the non-linear response, and high-precision processing is possible. The basic characteristics of such a femtosecond laser have already been reported in Non-Patent Document 1.
The fact that non-thermal processing is possible does not cause the molten material to scatter around the processed portion because the processed material does not melt.
[0039]
Next, as shown in FIG. 9, in a conventional YAG laser or carbon dioxide laser having a pulse width of nanoseconds or more, the irradiation energy amount (laser fluence) and the processing volume (dimension) are in a substantially linear proportional relationship.
[0040]
However, in a femtosecond laser with a pulse width of 1 picosecond or less, the irradiation energy amount (laser fluence) and the processing dimension are in a non-linear relationship. In particular, it has only a sub-μm spread in the direction perpendicular to the beam direction, that is, in the width direction, and processing progresses mainly in the depth direction.
[0041]
The inventor is in the midst of earnest research on precision processing of electronic circuit elements and wiring widths, and when processing is performed using a femtosecond laser of 1 picosecond or less regardless of the material, as shown in FIG. It was confirmed that the machining depth proportional to the amount could not be obtained, that is, the machining depth was almost constant with a nanometer (nm) gradient in a certain energy range, and the machining proceeded by orders of magnitude with a certain irradiation energy amount. .
[0042]
When the irradiation energy amount is gradually increased from the irradiation energy amount 0, the processing (processing depth) proceeds in nanometer (nm) order up to a certain irradiation energy amount. Thereafter, processing (processing depth) proceeds at a stretch in the order of sub-μm (micrometer). The irradiation energy amount (value) at which the first sub-μm order processing is started is called an ablation threshold value.
[0043]
It was also confirmed that the second and third threshold values appear as the irradiation energy amount is further increased. In other words, by using a femtosecond laser with a pulse width of 1 picosecond or less, even if there is a variation in the amount of irradiation energy, if it is within the range of the irradiation energy value at which processing stagnate, stable dimensions (processing depth) Has been found to be possible.
[0044]
On the contrary, if the depth of the recess to be processed is set in the threshold values (a), (b) and (c) where the processing in the depth direction in the processing depth characteristic with respect to the irradiation energy amount shown in FIG. Even if the energy value fluctuates, the depth of the recess coincides with the set value with, for example, sub-μm accuracy. Thus, the setting of irradiation energy is simplified by using the non-linear processing characteristic shown in FIG. 8 of the femtosecond laser.
[0045]
Patent Document 1 shows that this is not an error of the inventor's experiment but is theoretically correct. According to Patent Document 1, an experimental result is reported that there are three steps (substantially constant values) during 700 nm processing in processing of individual low molecular weight organic compounds.
[0046]
The inventor conducted an experiment using a copper foil having a thickness of 12 μm as a sample. According to this experimental result, the processing depth progressed in 5 steps, 5 μm, 9 μm, and 11 μm in three steps (threshold of three steps), penetrated the copper foil in the fourth step, and reached the underlying support substrate. However, there is no change in the processing width at the copper foil surface position. This is confirmed by the fact that a plurality of grooves were processed using the irradiation energy amount as a parameter, but no significant difference was found in the processing width in all of them.
[0047]
Further, as shown in FIG. 10, the oscillation wavelength of the femtosecond laser used this time is approximately 780 nm, which is out of the optical energy absorption band of copper (approximately 400 nm or less), but with sufficient processing. It was confirmed that processing independent of the light absorption wavelength of the material was possible. As shown in Patent Document 1 as an example, the light absorption band of a material such as copper or glass is a wavelength region of 400 nm or less. Nevertheless, it is possible to use femtosecond lasers with about twice the wavelength.
[0048]
As described above, the present invention applies the stepwise processing progression principle shown in FIG. 8 possessed by the femtosecond laser and the non-thermal processing characteristics with low material selectivity shown in FIGS. It is possible to stably process a three-dimensional microstructure on the order of sub-μm with respect to a processing target that is mixed or stacked.
[0049]
Hereinafter, specific embodiments of the present invention will be described with reference to the drawings.
Normally, an electronic element refers to a passive element (resistor, capacitor, inductor, etc.) that has been marked, but in this specification, a resistor embedded in a recess formed in a processing material according to the present invention, Capacitors and inductors include not only these electronic elements themselves but also parts constituting electronic elements such as resistors, dielectrics, and magnetic bodies formed by filling the concave portions with the material.
[0050]
(First embodiment)
FIG. 1 is a manufacturing process diagram showing a method for manufacturing a printed wiring board using a material processing method using an ultrashort pulse laser according to the first embodiment of the present invention. In this printed wiring board, a resistor constituting an electronic element is embedded in the substrate. The same parts as those in the manufacturing process diagram showing the manufacturing method of the conventional printed wiring board shown in FIG. 11 are denoted by the same reference numerals, and detailed description of the overlapping parts is omitted.
[0051]
First, a copper-clad substrate 3 in which a copper foil 2 having a thickness of about 10 μm is attached to a base material 1 made of a composite material containing an organic material such as glass epoxy and having a thickness of about 0.5 mm to several mm is created (see FIG. 1 (a)). Next, a photosensitive resist 4 is applied to the surface of the copper foil 2 of the copper-clad substrate 3 (FIG. 1B), and then pattern exposure of a wiring pattern (electronic circuit) is performed on the resist 4 (FIG. 1). (C)) and development (FIG. 1D) are sequentially performed.
[0052]
Subsequently, the copper foil 2 is removed by etching according to the exposure pattern to form a wiring pattern (electronic circuit) (not shown) (FIG. 1 (e)). After the etching is completed, the resist 4 is stripped with a solvent to expose the wiring pattern (FIG. 1 (f)).
[0053]
Next, the insulating film 7 is formed on the upper surface of the copper-clad substrate 3 where the wiring pattern is exposed by a lamination or coating process (FIG. 1G). The insulating film 7 is irradiated with a femtosecond laser 12 having a pulse width of about 150 femtoseconds to form a recess (filling groove) 13 with sub-μm accuracy (FIG. 1 (h)).
[0054]
In this case, the irradiation position of the femtosecond laser 12 is not continuously moved while irradiating the laser within the formation region of the recess (filling groove) 13, but by changing the irradiation position many times and performing laser irradiation, A wide formation region of the recess (filling groove) 13 is processed.
[0055]
Next, a resistance material is formed by filling a recess (filling groove) 13 formed on the surface of the copper-clad substrate 3 (base material 1) with a resistance material (FIG. 1 (i)). Although not shown, the surface of the resistor 5 may be smoothed thereafter. Finally, an insulating film 14 is formed on the upper surface of the resistor 5 by lamination or a coating process (FIG. 1 (j)).
In this way, a printed wiring board in which the resistor 5 constituting the electronic element is embedded in the substrate is manufactured.
[0056]
(Second Embodiment)
FIG. 2 is a manufacturing process diagram showing a method for manufacturing a printed wiring board using a material processing method using an ultrashort pulse laser according to the second embodiment of the present invention. Also in this printed wiring board, the resistor constituting the electronic element is embedded in the substrate. The same parts as those in the manufacturing process diagram showing the method of manufacturing the printed wiring board of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and detailed description of the overlapping parts is omitted.
[0057]
A substrate 3a made of a base material 1 made of a composite material such as glass epoxy and having a thickness of about 0.5 mm to several mm is formed (FIG. 2A). The substrate 3a is irradiated with a femtosecond laser 12 having a pulse width of about 150 femtoseconds to form a recess (filling groove) 13 with sub-μm accuracy (FIG. 2B). Next, a resistance material is formed by filling a recess (filling groove) 13 formed on the surface of the substrate 3a (base material 1) with a resistance material (FIG. 2C). Although not shown, the surface of the resistor 5 may be smoothed thereafter.
[0058]
After filling the resistor 5 into the recess (filling groove) 13, a wiring pattern is formed by lithography. That is, after applying the photosensitive resist 4 (FIG. 2D), pattern exposure (FIG. 2E) and development (FIG. 2F) are sequentially performed. Subsequently, wiring is formed by an additive method according to the exposure pattern, and a copper foil 2 corresponding to the exposure pattern is formed (FIG. 2G). Finally, the insulating film 7 is formed on the copper foil 2 on which the wiring is formed by a lamination or coating process (FIG. 2 (h)).
In this way, a printed wiring board in which the resistor 5 constituting the electronic element is embedded in the substrate is manufactured.
[0059]
(Third embodiment)
3 and 4 are manufacturing process diagrams showing a method for manufacturing a printed wiring board using a material processing method using an ultrashort pulse laser according to the third embodiment of the present invention. In this printed wiring board, a dielectric (capacitor) constituting an electronic element is embedded in a substrate. The same parts as those in the manufacturing process diagram showing the method for manufacturing the conventional printed wiring board shown in FIGS. 12 and 13 are denoted by the same reference numerals, and detailed description of the overlapping parts is omitted.
[0060]
A copper-clad substrate 3 in which a copper foil 2b having a thickness of about 10 μm is pasted on a base material 1 made of a composite material containing an organic material such as glass epoxy and having a thickness of about 0.5 mm to several mm is created (FIG. 3 ( a)). Next, a photosensitive resist 4 is formed on the surface of the copper foil 2b by a dry film resist lamination (DFR lamination) method (FIG. 3B), and then pattern exposure of a wiring pattern (electronic circuit) including a lower electrode is performed. (FIG. 3C) and development is performed (FIG. 3D).
[0061]
Subsequently, the wiring pattern (electronic circuit) of the lower electrode 8b of the dielectric (capacitor) is formed by removing the copper foil 2b in accordance with the exposure pattern by etching (FIG. 3E). After the etching is completed, the resist 4 is removed with a solvent to expose the wiring pattern of the lower electrode 8b (FIG. 3F). An insulating resin 9 is pasted on the upper surface of the wiring pattern of the lower electrode 8b by a dry film resist laminate (DER) method (FIG. 3G).
[0062]
Next, the copper-clad substrate 3 with the insulating resin 9 formed on the upper surface is irradiated with a femtosecond laser 12 having a pulse width of about 150 femtoseconds, and a recess (filling groove) whose depth reaches the wiring pattern of the lower electrode 8b. ) 13 is formed with sub-μm accuracy (FIG. 3H). Then, the dielectric 11 is applied and filled into the formed recess (filling groove) 13 (FIG. 4 (i)). Although not shown, the surface of the dielectric 11 may be smoothed thereafter.
[0063]
After the dielectric 11 is applied and filled in the recess (filling groove) 13, the copper foil 2b is formed by electroless plating (FIG. 4 (j)). Thereafter, dry film resist lamination (DFR), exposure, development, etching, and resist stripping are sequentially performed again by lithography (FIGS. 4 (k), (l), (m), and (n)). An upper electrode 8 a is formed on the dielectric 11.
[0064]
In this way, a printed wiring board in which the dielectric 11 is embedded in the substrate is manufactured.
[0065]
(Fourth embodiment)
FIG. 5 is a schematic configuration diagram of a printed wiring board according to the fourth embodiment of the present invention. FIG. 5A is a top view, FIG. 5B is a cross-sectional view of the printed wiring board of FIG. 5A taken along the line aa ′, and FIG. 5C is FIG. It is sectional drawing at the time of cut | disconnecting the printed wiring board of (a) by bb 'line. In a printed wiring board as a meander-type element which is one form of this inductor, a magnetic body constituting an electronic element is embedded in a substrate.
[0066]
In this printed wiring board, for example, three long concave portions (filling grooves) 22 are formed in a substrate 21 made of a resin material, and one continuous piece is formed on the surface of the substrate 21 and the bottom surface of each concave portion 22. A conductor 23 forming a coil is formed. A magnetic body 24 is embedded in each recess 22 having a conductor 23 formed on the bottom surface.
[0067]
A magnetic body 24 is provided in order to increase the inductance value of the coil composed of the conductor 23 wired in a bellows shape. Since the magnitude of the inductance is determined by the amount (volume) of the magnetic body 24, it is necessary to process and form the recess (filling groove) 22 for housing the magnetic body 24 with high accuracy.
[0068]
FIG. 6 is a manufacturing process diagram showing a method for manufacturing a printed wiring board in which a magnetic body 24 constituting an electronic element is embedded in a substrate 21.
[0069]
A substrate 21 made of a resin material is irradiated with a femtosecond laser 12 having a pulse width of about 150 femtoseconds to form a recess (filling groove) 22 with sub-μm accuracy (FIG. 6A). Next, a resist 4 is applied to the upper surface of the substrate 21 in which the recess 22 is formed (FIG. 6B), and the wiring pattern of the conductor 23 is subjected to pattern exposure and developed (FIG. 6C). Thereafter, wiring is formed by an additive method, and a wiring pattern of the conductor 23 corresponding to the exposure pattern is formed (FIG. 6D). Thereafter, the resist 4 is peeled off with a solvent (FIG. 6E), and the magnetic material 24 is filled in each of the recesses 22 in which the conductors 23 are formed on the bottom surface (FIG. 6F).
[0070]
In this way, a printed wiring board in which the magnetic body 24 is embedded in the substrate 21 is manufactured.
[0071]
In the material processing method, the printed wiring board, and the printed wiring board manufacturing method using the ultrashort pulse laser configured as described above, the resistor 5, the dielectric 11, and the magnetic body 24 are attached to the substrate using the femtosecond laser 12. Recesses (filling grooves) 13 and 22 for embedding are formed.
[0072]
Therefore, as described with reference to FIG. 8, the variation in the machining width in the direction perpendicular to the laser irradiation direction is extremely small, and only the machining depth of the recesses 13 and 22 changes. 13 and 22 can be processed. Further, since the processing depth changes stepwise with respect to the amount of irradiation energy, the processing depth is suppressed from being affected by fluctuations in the amount of irradiation energy. As a result, the sub-μm order was secured as the processing accuracy of the recesses 13 and 22. In this case, the depths of the recesses 13 and 22 can be set to at least three levels of threshold values a, b, and c at which the processing in the depth direction in the processing depth characteristics stagnate to the irradiation energy amount shown in FIG. .
[0073]
As described with reference to FIG. 7, since processing is performed with the femtosecond laser 12 whose pulse width is shorter than the thermal relaxation time, processing without thermal influence is possible, and processing accuracy of the formed recesses 13 and 22 is further improved. Make sure.
[0074]
Furthermore, it is not necessary to select a laser light source according to the light absorption characteristics of the material shown in FIG. 10, and one laser processing system can be used for inorganic materials such as glass, organic materials such as resin, metallic materials such as copper, and organic materials. The recesses 13 and 22 can be formed on a substrate using any material such as a composite material in which an inorganic material is mixed and a laminate material in which a composite material in which an inorganic material is mixed in an organic material and a metal material are laminated. .
[0075]
In addition, since the recesses 13 and 22 are formed by using the femtosecond laser 12, in this printed wiring board manufacturing process, complicated sography including resist coating, pattern exposure, development, etching treatment, resist stripping, etc. One step can be omitted.
[0076]
Furthermore, since the recesses 13 and 22 are formed with sub-μm order accuracy, the volume of the resistor 5, dielectric 11, and magnetic body 24 embedded (filled) in the recesses 13 and 22 is also highly accurate. The resistance value, the capacitance value, and the inductance value of the electronic element composed of the resistor 5, the dielectric 11, and the magnetic body 24 can be matched with the design value with high accuracy. . As a result, as shown in FIG. 11G, the resistor 5 is trimmed by using the YAG laser 6 so that the resistance value of the resistor 5 is within the design allowable value, or as shown in FIG. As shown, it is not necessary to carry out an adjustment process for trimming the upper electrode 8a using the YAG laser 6 so that the capacitance value between the electrodes 8a and 8b of the dielectric 11 is within the design allowable value.
Thus, the manufacturing process of a printed wiring board can be simplified.
[0077]
In addition, this invention is not limited to embodiment mentioned above.
The substrate is not limited to one formed of one type of insulating material, and may be a laminated circuit substrate having two or more layers. As described above, a composite material in which an inorganic material is mixed with an organic material, a laminated material in which a composite material in which an inorganic material is mixed with an organic material, and a metal material are laminated as the substrate material is effective. .
[0078]
【The invention's effect】
As described above, in the material processing method, the printed wiring board manufacturing method, and the printed wiring board using the ultrashort pulse laser according to the present invention, an electronic element such as a resistor, a capacitor, an inductor, or the like is used on the substrate by using a femtosecond laser. A recess (filling groove) is formed for embedding a part.
[0079]
Therefore, the step of forming the recess can be simplified, the dimensional accuracy of the formed recess can be greatly improved, and even if the substrate is a mixture or laminated of a plurality of types of materials, the recess can be easily and high. Can be formed with accuracy.
[0080]
Furthermore, in the printed wiring board manufacturing method, in addition to the above-described effects, it is possible to easily realize high processing accuracy without using a complicated processing process such as a lithography process, and to form an embedded electron. It is not necessary to adjust the characteristic value for the element, and the manufacturing process can be simplified.
[Brief description of the drawings]
FIG. 1 is a manufacturing process diagram showing a method for manufacturing a printed wiring board using a material processing method using an ultrashort pulse laser according to a first embodiment of the present invention.
FIG. 2 is a manufacturing process diagram showing a method for manufacturing a printed wiring board using a material processing method using an ultrashort pulse laser according to a second embodiment of the present invention.
FIG. 3 is a manufacturing process diagram showing a method for manufacturing a printed wiring board using a material processing method using an ultrashort pulse laser according to a third embodiment of the present invention.
FIG. 4 is a manufacturing process diagram showing a method for manufacturing a printed wiring board using a material processing method using an ultrashort pulse laser according to the third embodiment of the present invention.
FIG. 5 is a schematic configuration diagram of a printed wiring board according to a fourth embodiment of the present invention.
FIG. 6 is a manufacturing process diagram showing a method for manufacturing a printed wiring board according to the fourth embodiment;
FIG. 7 is a characteristic diagram showing the relationship between the laser pulse width and the thermal diffusion length in the work material caused by laser irradiation.
FIG. 8 is a graph showing the relationship between the irradiation energy of a femtosecond laser and the processing depth.
FIG. 9 is a diagram showing the relationship between the general laser irradiation energy amount and the processing volume.
FIG. 10 is a diagram showing light energy absorption characteristics of each material.
FIG. 11 is a manufacturing process diagram showing a conventional method for manufacturing a printed wiring board;
FIG. 12 is a manufacturing process diagram showing another conventional method for manufacturing a printed wiring board.
FIG. 13 is a manufacturing process diagram showing another conventional method for manufacturing a printed wiring board.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Base material, 2, 2a, 2b ... Copper foil, 3 ... Copper-clad board | substrate, 3a, 21 ... Board | substrate, 4 ... Resist, 5 ... Resistor, 7, 14 ... Insulating film, 8a ... Upper electrode, 8b ... Lower part Electrode, 9 ... insulating resin, 11 ... dielectric, 12 ... femtosecond laser, 13, 22 ... recess (filling groove), 23 ... conductor, 24 ... magnetic material

Claims (9)

A material processing method using an ultrashort pulse laser, wherein a substrate formed of an insulating material is irradiated with a femtosecond laser to form a recess for embedding an electronic element in the substrate. A super short characterized by irradiating a femtosecond laser to a substrate formed of a composite material in which an inorganic material is mixed with an organic material, and forming a recess for embedding an electronic element in the substrate. Material processing method by pulse laser. An ultrashort pulse laser material characterized by irradiating a femtosecond laser on a substrate on which a metal layer and an insulating material layer are laminated to form a recess for embedding an electronic element on the substrate. Processing method. Irradiating a femtosecond laser to a substrate in which a composite material layer in which an inorganic material is mixed with an organic material and a metal layer are laminated, and forming a recess for embedding an electronic device on the substrate. A material processing method using an ultra-short pulse laser. The material processing method using an ultrashort pulse laser according to any one of claims 1 to 4, wherein the electronic element is any one of a resistor, a capacitor, and an inductor. 6. The depth of the recess to be processed is within a threshold region in the depth direction in the processing depth characteristic with respect to the irradiation energy amount of the femtosecond laser. The material processing method by the ultrashort pulse laser of description. Irradiate femtosecond laser to one side of the substrate made of insulating material to form a recess in this substrate,
By filling the material of the electronic device in the formed recess, the electronic device is embedded in the recess,
A method of manufacturing a printed wiring board, comprising: forming a metal layer having an electronic circuit including an electrode for the electronic element on the one surface of the substrate in which the electronic element is embedded. Forming an electronic circuit including an electrode for an electronic element on the metal layer in the substrate in which the insulating material layer and the metal layer are stacked;
Forming an insulating film layer on the upper surface of the metal layer in the substrate;
Irradiating femtosecond laser to the side of the insulating film layer of the substrate on which the insulating film layer is formed, forming a recess reaching the electronic circuit on the substrate,
A method of manufacturing a printed wiring board, wherein the electronic device is embedded in the recess by filling the formed recess with a material of the electronic device. The printed wiring board manufactured with the manufacturing method of the printed wiring board of the said Claim 7 or 8.

Images