JP2008112876A - Laser beam machining method, and multilayer ceramic substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser beam machining method for forming a sufficient through hole in a substrate of a multilayer structure, in which a resin carrier film is arranged on a green ceramic substrate having a high content rate of a glass component. <P>SOLUTION: In the laser beam machining method, the through hole 3 of the substrate in the multilayer structure where the carrier film 1 consisting of a resin material is formed on an upper face of a green sheet 2 being the green ceramic substrate comprising a ceramic aggregate and the glass component. The through hole is formed in the substrate of the multilayer structure by giving a step for punching the carrier film 1 by using a first laser beam with good absorptivity with respect to the resin material for punching the carrier film 1 and a step for punching the green sheet 2 by using a second laser beam having good absorptivity with respect to the ceramic material and bad absorptivity with respect to the glass material. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a ceramic green body containing ceramic and glass, in particular, a ceramic green body for laser processing, particularly a ceramic green body for laser processing, and a method for producing a glass-ceramic composite substrate using the same.

  In recent years, glass-ceramic composite substrates have been used in various products. For example, in multilayer ceramic substrates, in order to increase the speed of circuit signal transmission as the speed of computers and the frequency of communication equipment increase, Low dielectric constant, low dielectric loss, low sintering temperature to enable simultaneous firing with low melting point wiring materials with low resistance, fine via diameter and via pitch, and high density wiring It has been required to meet the requirements of Therefore, in order to satisfy these requirements, research is being conducted on the combination of ceramic aggregate and glass in a glass-ceramic composite substrate capable of lowering the melting point.

In addition, as a method of opening a through hole in a ceramic substrate with a laser, a method of adjusting the hole shape by irradiating a laser while turning the hole around the circumference of one through hole to be configured (Patent Document 1) In order to adjust the hole shape, the ceramic substrate contains an absorbent for absorbing laser light in advance (Patent Document 2), or the hole shape is adjusted by adjusting the components of the green sheet (Patent Document 3). .
JP 11-54885 A Japanese Patent Laid-Open No. 2000-1559577 JP 2002-274950 A

  To manufacture a multilayer ceramic substrate, a green body containing at least ceramic powder, glass powder, and a binder is first formed on a support, and then through holes for electrically connecting wiring layers are formed in each green body. To do. For forming through holes, NC punching and laser processing, which are conventionally used, are generally used, but via diameters of φ120 μm to φ100 μm and pitches of 250 μm or less are increasing. Processing, that is, drilling with a laser beam has become common.

  However, if a glass-ceramic composite substrate has a conventional binder such as acrylic or butyral or a carrier film disposed on the top surface of a green sheet used for protection, the laser output is reduced when a through hole is formed by laser processing. If the height is high, the periphery of the through hole on the laser beam incident side and the periphery of the carrier film are greatly raised, so that when the conductor pattern is printed on the surface of the green body, the pattern becomes thin around the through hole and breakage is likely to occur. If an excimer laser is used, this problem can be solved, but the processing speed is slow and impractical. If the laser output is weak, a through hole cannot be formed. In addition, there is a problem in that the conventional method has a limitation in processing speed in order to reliably form a via diameter of 100 μm and a via pitch of 250 μm or less by using drilling such as NC punching.

  In the method of adjusting the hole shape by irradiating the laser while rotating the hole around the circumference, dividing the hole shape into several times at the time of the above-mentioned hole processing, as well as the processing time, ceramic aggregate and glass, Since heat is applied to the carrier film several times, instability of the hole shape may be caused, and furthermore, it is difficult to drill a small diameter hole of φ100 μm or less.

  In addition, the method of incorporating a pigment or a laser light absorber into a ceramic substrate may affect the material properties of the ceramic substrate. At the same time, adjusting the components of the green sheet increases the possibility of laser processing, but there is a possibility of demerits in material properties and cost. In both cases, there is no problem with the hole shape of the green sheet, but in processing of the ceramic substrate on which the carrier film is also arranged, the problem of the rise of the carrier film and the hole shape is not avoided, and the deformation affects the process. there is a possibility.

  In general, either a YAG laser or a CO2 laser is used as the laser, and either of them may cause a problem of swelling of a green sheet or a carrier film, or a hole processing state or a hole shape. .

  In the manufacturing process of a ceramic substrate having a high glass component (glass, quartz) content, the present invention includes a carrier film made of a resin on a green sheet, and when forming a through hole in the green sheet by laser processing, the carrier film It is another object of the present invention to provide a method and an apparatus capable of suppressing the bulge around the through hole of the green sheet and improving the hole shape and the hole processing state.

  In order to achieve the above object, the laser processing method of the present invention is applied to a multilayer structure substrate in which a carrier film made of a resin material is formed on the upper surface of a green sheet which is a raw ceramic substrate containing a ceramic aggregate and a glass component. In the laser processing method for forming a through hole, a step of forming a hole in the carrier film by using a first laser beam having good absorbability with respect to a resin material for the formation of the carrier film, following the first step, ceramic Forming a through hole in a substrate having a multilayer structure having a step of drilling a green sheet using a second laser beam that absorbs the material and does not absorb the glass material. .

  The multilayer ceramic substrate of the present invention is characterized in that it is formed by laminating ceramic substrates on which through holes are formed by the method according to claim 1.

  According to the drilling method for a ceramic substrate of the present invention, in the manufacturing process of a ceramic substrate having a high glass component (glass, quartz) content, a resin carrier film is present on the green sheet, When forming through-holes by laser processing, the carrier film and green sheet can be prevented from rising due to laser processing, glass components are processed, and the phenomenon of glass spheres that become lumps can also be suppressed. It becomes possible to make a processing state favorable.

  In addition, although there are concerns about costs due to the use of multiple lasers, in recent years, laser markers with high accuracy and cost merit have become widespread and can be dealt with, so conventional large and expensive laser processing machines I think that there will be more merit than

  Embodiments of a method for drilling a raw ceramic substrate and a multilayer ceramic substrate according to the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is an external perspective view of a drilling method and apparatus for a substrate containing a multilayer ceramic material and glass material by laser processing in Example 1 of the present invention.

  FIG. 2 is a diagram for explaining a drilling state in each process step of the present invention.

  FIG. 3 is a diagram for illustrating an example of a conventional drilling apparatus using laser processing, and FIG. 4 is a diagram for explaining a point of concern in drilling in the conventional example.

  When a resin carrier film 1 is present on a green sheet 2 containing at least ceramic powder, glass powder and a binder, and the through hole 3 is formed in the green sheet 2 by laser processing, an example of an apparatus is shown in FIG. As shown in the figure, only the resin carrier film 1 is provided with a laser device 4 as a first step for drilling in a predetermined hole position that requires the through hole 3, and the drilled resin product is made. As a second step, the carrier film 1 is provided with a laser device 5 for drilling at a predetermined position where the through hole 3 is required with respect to the green sheet 2, and the green sheet 2 is adsorbed or fixed. And a moving means 7 and 8 for transferring the pallet 6 on which the green sheet 2 is placed.

  First, as shown in FIG. 2 (a), in the first step, the laser device 4 performs drilling only on the carrier film 1. In this step, it is desirable to use a CO2 laser with a wavelength of 9.3 μm. At this time, the thickness of the carrier film 1 is about 100 μm, and the laser irradiation condition is about 5 to 10 W by fixed point irradiation. Here, the laser beam 11 has an output sufficient to penetrate the resin carrier film 1, but the green sheet 2 made of ceramic or glass material has a poor absorption rate, so that no processing is performed. Then, only the resin carrier film 1 is drilled at all predetermined drilling positions.

  Although it is not shown in the drawings, the image processing apparatus performs determination / determination for determining whether or not to drill the carrier film 1 alone. The number of inspections may be 100%, or may be several in an apparatus with stable laser power. Since the color of the carrier film 1 is not specified, it is possible to confirm the drilling without any problem even if, for example, the processed hole is processed from above. Further, since the absorption rate differs between the carrier film 1 and the green sheet 2 depending on the wavelength of the laser device 4, the carrier film 1 can be drilled, but the green sheet 2 cannot be drilled. In other words, there is a case where determination by image processing is not necessary. In that case, the power degradation may be confirmed by periodically measuring the power of the laser device 4. That is, since an output sufficient to penetrate the resin carrier film 1 is irradiated, if the output power of the laser device 4 is managed, the hole in the carrier film 1 can be formed.

  Thereafter, the sheet is transferred, and in the second step, as shown in FIG. 2 (b), the green sheet 2 that has been drilled in the carrier film 1 in the previous step is required to be drilled. Drilling is performed by the laser device 5. In this step, it is desirable to use a YAG laser. In this case, the green sheet 2 can be processed without problems even if the hole penetrating the resin carrier film 1 is smaller than the predetermined hole diameter. A YAG-based laser has a high absorption rate for a ceramic material and a low absorption rate for a glass material. Therefore, hole processing is performed while thermal processing is performed on the ceramic material.

  To manufacture a multilayer ceramic substrate, first, a green sheet 2 which is a raw ceramic substrate containing at least ceramic powder, glass powder and a binder is formed on a support, and then a through hole for electrically connecting wiring layers. 3 is formed on each green sheet 2, but conventionally, the punching process and the laser process that have been conventionally used are generally used to form the through hole 3.

  However, recently, the diameter of the through hole 3 has increased from φ120 μm to φ100 μm and the pitch interval of 250 μm or less, and NC punching processing is such fine processing, and narrow pitch processing has become difficult. In order to achieve this, laser processing, that is, drilling with a laser beam has become common. In addition, the diameter of the through hole 3 is expected to further decrease in the future, and it is necessary to select an optimum laser device. Among them, the optimization for the material is an important point, and is an item necessary for efficient processing.

  For example, laser devices with high laser output peak power, such as excimer lasers and ultrashort pulse lasers, and laser devices capable of processing such as ablation rather than thermal processing, do not have a significant problem with the material absorption rate. It is expensive and may become a bottleneck for introduction.

  In addition, when the resin carrier film 1 and the green sheet 2 are processed in one step in order to form the through hole 3 as shown in FIG. 3, either of the short pulse lasers is used. When the through-hole 3 is processed by using the apparatus 4, the resin carrier film 1 is processed with no problem because the CO2 laser has a high absorptance, but the green containing ceramic material and glass material is used. Although there is no problem with the ceramic material for the sheet, the glass material is also slightly absorbed, so that the glass material is melted, so that a glass ball 9 is generated inside the through hole 3 as shown in FIG. The glass sphere 9 is always generated when the glass material absorbs the wavelength of the CO2 laser and is melted by heat, apart from being large and small.

  In contrast, when a YAG laser is used, since the absorption rate is very poor when the resin carrier film 1 before processing the green sheet 2 is processed, the resin carrier film 1 as shown in FIG. Does not vaporize due to heat and becomes liquid, forming a bulge 10 around the hole. This swell may cause damage to the green sheet 2 in the process of stacking the sheets in the subsequent process, or the swell 10 may be caught when filling with the carrier film 1 attached. Therefore, it is desirable to process in as small a size as possible.

  In this regard, in the present invention, by using the laser devices 4 and 5 suitable for each material, there is a concern that may occur when the resin carrier film 1 is processed by the laser device, and the green sheet 2 is laser-treated. It is possible to eliminate concerns that may occur by processing with an apparatus. That is, in the first step using a CO2 laser that absorbs well with respect to the carrier film 1, the through-hole is formed in the carrier film 1 with almost no swell of the carrier film 1 that occurs when a YAG laser is used. can do. In the second step, since a YAG laser having a high absorption rate to the ceramic material and a low absorption rate to the glass material is used without using the CO2 laser, the hole processing is performed with almost no generation of the glass balls 9. it can.

Further, although there are concerns about the position accuracy due to the two steps, the position accuracy of the galvano mirror drive system for irradiating the laser beam 11 of the laser devices 4 and 5 to a predetermined hole position and the positions of the stages 7 and 8 are increased. By improving the accuracy, the total positional accuracy of both can be achieved within ± 10 μm, and there is no problem. Even if an error of several μm occurs or the diameter of the hole formed by the laser device 4 in the first step is small, the laser-based carrier film 1 is processed in a small amount by the laser device 5 in the second step. Through-hole processing is possible in the green sheet 2. In that sense, it is necessary to pay attention to the laser irradiation conditions of the laser device 4 in the first process so that the hole diameter does not increase in consideration of the work of filling the through holes with the conductor in the subsequent process. Therefore, the laser irradiation conditions are determined in advance. However, since drilling can be performed at ± 5% of the target hole diameter, as described above, there is no problem with periodic laser power management. It is possible to satisfy. In addition, there is a concern about the disadvantage of cost by using two laser devices, but the recent laser marking devices 4 and 5 are very low in cost, and the cost is greatly increased. It is disappearing.

  In order to manufacture a multilayer ceramic substrate, the carrier film 1 is removed after the above-described drilling process, and a conductive material for electrically connecting the upper and lower substrate surfaces of the green sheet 2 which is a raw ceramic substrate is formed in a through hole for writing. A wiring pattern is formed on the surface of the green ceramic substrate by printing or the like. Then, several to several tens of green ceramic substrates of each layer formed in this manner are stacked and pressed to form a laminate, which is then placed in a furnace and fired at a high temperature. The method of forming a through hole by laser processing of the present invention is suitable for manufacturing a multilayer ceramic substrate having a high-density, high-definition pattern in which the diameter of the through-hole 3 is φ100 μm or less and the pitch is 250 μm or less.

  In the method and apparatus for drilling a ceramic substrate according to the present invention, a resin carrier film is present on the green sheet in the manufacturing process of the ceramic substrate having a high glass component (glass, quartz) content. When forming through-holes by laser processing, the carrier film and green sheet can be prevented from rising due to laser processing, glass components are processed, and the phenomenon of glass spheres that become lumps can also be suppressed, resulting in high density and high definition. Suitable for the production of patterned multilayer ceramic substrates.

FIG. 3 is an external perspective view of a laser processing apparatus used for the laser processing method in Embodiment 1 of the present invention. The figure for demonstrating the drilling state using the laser processing apparatus used for the laser processing method in Example 1 of this invention External perspective view of conventional laser processing equipment The figure which showed the drilling state using the conventional laser processing equipment The figure which showed another drilling state using the conventional laser processing equipment

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Resin-made carrier film 2 Green sheet 3 Through-hole 4 Laser apparatus 5 Laser apparatus 6 Pallet 7 Transfer means 8 Transfer means 9 Glass ball 10 Rise of resin material 11 Laser light

Claims (5)

In a laser processing method for forming a through hole of a multilayer structure substrate in which a carrier film made of a resin material is formed on an upper surface of a green sheet which is a raw ceramic substrate containing a ceramic aggregate and a glass component,
Drilling the carrier film using a first laser beam that is highly absorbent to the resin material for drilling the carrier film;
Subsequent to the first step, drilling the green sheet using a second laser beam that absorbs well with the ceramic material and does not absorb with the glass material;
A laser processing method, comprising: forming a through hole in a substrate having a multilayer structure including: 2. The laser processing method according to claim 1, wherein a CO 2 laser having a wavelength of 9.3 μm is used as the first laser light. The laser processing method according to claim 1, wherein a YAG laser is used as the second laser light. 2. The laser processing method according to claim 1, wherein a through hole is formed in the carrier film in the first drilling step using a CO2 laser having a predetermined power output, and the second drilling step is performed. A multilayer ceramic substrate formed by laminating ceramic substrates on which through holes are formed by the method according to claim 1.

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