JP2013214667A - Ceramic wiring board manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a manufacturing method of a ceramic wiring board for a multi-piece wiring board and the like which has a predetermined size and shape, and which has a plurality of unit ceramic wiring boards where a conductor layer of a predetermined width is formed on a surface which surrounds openings of cavities, and which includes split grooves among the unit ceramic wiring boards.SOLUTION: A manufacturing method of a ceramic wiring board 1 having split grooves 24 which split a conductor layer 12 formed on a surface 3 of a ceramic layer 16 and extend along the surface 3 comprises a process of irradiating YVOlaser beams 22 on the conductor layer 12 formed on the surface 3 of the ceramic green sheet 16 along a thickness direction of the conductor layer 12 and the green sheets 16, 17 lying under the conductor layer 12 to form the split grooves 24 along the surface 3 by continuous irradiation along the surface 3 of the green sheet 16.

Description

  The present invention relates to a method for manufacturing a ceramic wiring board including, for example, a product region having a plurality of unit ceramic wiring boards, and in which divided grooves are formed between the unit ceramic wiring boards.

  In order to stably and efficiently manufacture a ceramic substrate that does not generate micro cracks in the deep bottom of the notch groove, a YAG laser or carbon dioxide laser is applied to the surface of the green sheet for a multi-piece ceramic green sheet. A method of manufacturing a ceramic substrate has been proposed in which notched grooves (divided grooves) are formed along a scribe play line for dividing the plurality of ceramic substrates into individual pieces (see, for example, Patent Document 1). ).

According to the method for manufacturing a ceramic substrate described in Patent Document 1, it is possible to stably form a split groove having no crack in a deep bottom portion between adjacent ceramic substrates. However, since a YAG laser or carbon dioxide gas laser with relatively high energy and a large pulse width is used, the width of the opening of the dividing groove formed in the ceramic green sheet is excessively widened. Of the formed conductor layer, the side part along the dividing groove may be excessively removed. Therefore, a ceramic wiring board having a predetermined external dimension and shape cannot be obtained, or a conductor layer having a required width cannot be formed on the surface surrounding the cavity opening to braze a metal frame for sealing. There was a problem.
Further, for the internal conductor layer formed between the plurality of ceramic green sheets, when the divided grooves are formed together with the green sheet by the laser, the internal conductor exposed in the divided grooves is formed near the inner wall surface of the formed divided grooves. The end face side of the conductor layer may be partially removed or peeled off. For this reason, there is a problem that electrical conduction in the vicinity of the inner conductor layer may become unstable.

JP 62-232187 (pages 1-5, FIGS. 1-3)

  The present invention solves the problems described in the background art, for example, a plurality of unit ceramic wiring boards having a predetermined size and shape, or a conductor layer having a predetermined width formed on a surface surrounding an opening of a cavity. It is another object of the present invention to provide a method for manufacturing a ceramic wiring board, such as for multi-piece manufacturing, in which a plurality of grooves are formed between the wiring boards.

Means for Solving the Problems and Effects of the Invention

In order to solve the above-described problems, the present invention has been conceived by irradiating a ceramic green sheet having a conductor layer formed on at least the surface thereof with a YVO ₄ laser along the surface.
That is, the method for manufacturing a ceramic wiring board according to the present invention (Claim 1) is a method for manufacturing a ceramic wiring board that divides at least a conductor layer formed on the surface of the ceramic layer and has dividing grooves along the surface. And irradiating the conductor layer formed on the surface of the ceramic green sheet with a YVO ₄ laser along the thickness direction of the conductor layer and the green sheet positioned below the conductor layer, The method includes the step of forming a dividing groove along the surface by continuously irradiating along the surface.

According to this, a YVO ₄ laser having a lower energy and a smaller pulse width than the YAG laser or carbon dioxide laser, for example, along the thickness direction of the green sheet with respect to the conductor layer formed on the surface of the ceramic green sheet. And continuously irradiated along the surface of the green sheet. Therefore, the dividing grooves formed along the surface of the green sheet have a narrow and narrow V-shaped section with a deep bottom at the bottom, and an unfired conductor layer previously formed on the surface of the green sheet. It will not be removed excessively. Therefore, it has a plurality of unit ceramic wiring boards having a predetermined size and shape, or having a conductor layer and an inner conductor layer of the required width formed on the surface surrounding the cavity opening, and between these wiring boards. Thus, it is possible to reliably provide a method for manufacturing a ceramic wiring board for taking a large number of pieces in which divided grooves are formed, and a ceramic wiring board that requires divided grooves.
Furthermore, when the internal conductor layer is formed on the ceramic wiring board and the internal conductor layer is divided by the dividing groove, the vicinity of the end portion of the internal conductor layer exposed in the dividing groove is not excessively removed, And it becomes difficult to produce peeling.

In addition, although the said ceramic wiring board is mainly for picking up many pieces, the form which has the ear | edge part of the peripheral side and the single wiring board located in the center side may also be included.
The ceramic green sheet includes not only high-temperature fired ceramics such as alumina but also low-temperature fired ceramics such as glass-ceramics.
Furthermore, W or Mo is used for the conductor layer if the green sheet is for high-temperature fired ceramics, and Cu or Ag is used for low-temperature fired ceramics.
The conductor layer formed on the surface of the green sheet is a frame-shaped conductor layer for brazing a metal frame for sealing, or a single-layer ceramic substrate obtained by firing a single-layer green sheet. A ground wiring layer provided around the surface is included.
Furthermore, in addition to the conductor layer on the surface, an inner conductor layer positioned between the plurality of green sheets may be included. For example, a conductor layer serving as a wiring layer for connecting to a concave conductor layer provided at a corner of a ceramic substrate and connecting to an internal circuit or the like is exemplified.
The YVO ₄ laser is a laser using yttrium vanadate (YVO ₄ ) as a medium, and its wavelength is 1,064 nm.

The present invention also includes a method for manufacturing a ceramic wiring board (claim 2), wherein the YVO ₄ laser is a second to fourth harmonic YVO ₄ laser.
According to this, the frequency of a normal YVO ₄ laser is doubled (a half wavelength), tripled (a third wavelength), or quadrupled (a quarter). The second to fourth harmonic YVO ₄ laser having a wavelength of 1) is irradiated onto the conductor layer formed on the surface of the ceramic green sheet and irradiated along the surface. A narrow area is irradiated with a laser beam at a higher density in a straight line or the like. Accordingly, it is possible to form a division groove having a narrower groove width and a deeper depth than in the case of using a normal YVO ₄ laser.
The second, third, and fourth harmonics are twice, three times, and four times the frequency of the original fundamental wave (half wavelength, one third wavelength, one quarter wavelength). a frequency component having a wavelength), for example, the second harmonic of the YVO ₄ laser, wavelength of YVO ₄ laser of 532 nm.

Furthermore, the present invention includes a method for manufacturing a ceramic wiring board (Claim 3), wherein the repetition frequency of the YVO ₄ laser is 20 to 250 KHz.
According to this, for example, as compared with the case where a YAG laser having a repetition frequency peak of about 10 KHz is used, groove processing with a YVO ₄ laser with less than half energy can be performed with the same output, so that a narrow groove with a narrow groove width and a deep groove. Can be formed.
A preferable repetition frequency band of the YVO ₄ laser is 50 to 100 KHz.

The top view which shows the ceramic wiring board for multi-piece picking used as the object of this invention. (A) is the partial vertical sectional view along the XX line in FIG. 1, (b) is the partial vertical sectional view along the YY line in FIG. YVO ₄ schematic graph showing the characteristics of the laser and YAG laser. Schematic which shows the process of irradiating the said ceramic wiring board with the said laser. FIG. 3 is a partial vertical sectional view similar to the above after irradiation with a YVO ₄ laser according to the present invention. The same partial vertical sectional view as described above after irradiation with the YAG laser of the comparative example.

Hereinafter, modes for carrying out the present invention will be described.
In advance, ceramic powder such as alumina, binder resin, and solvent are weighed and blended in a required amount, and the resulting ceramic slurry is shaped into a sheet shape by the doctor blade method, so that four ceramic green sheets (hereinafter referred to as “ceramic green sheets”) Simply referred to as a green sheet). A via hole formed by punching each green sheet was filled with a conductive paste containing W or Mo powder to form a via conductor penetrating between the front and back surfaces of each green sheet.
Next, at least one of the front and back surfaces of each green sheet was screen-printed with a predetermined pattern to form a conductor layer with a predetermined pattern made of the same conductive paste as described above. Furthermore, a plurality of through-holes having a rectangular (rectangular or square) shape in plan view are formed adjacent to each other vertically and horizontally by using a punching device including a punch having a square cross section on the two-layer green sheet that will be the upper layer later. did. The two green sheets on the upper layer side and the remaining two green sheets on the lower layer side were laminated.

As a result, as shown in the plan view of FIG. 1, a multi-piece ceramic wiring board 1 which is an object of the present invention was obtained. 2A is a partial vertical sectional view taken along line XX in FIG. 1, and FIG. 2B is a partial vertical sectional view taken along line YY in FIG.
As shown in FIG. 1, a multi-piece ceramic wiring board 1 has a plurality of unit ceramic wiring boards (ceramic packages) having a cavity 6 opened in the surface 3 on the center side of the surface 3 that is rectangular in plan view. ) 6 is disposed adjacent to the product region 2 in the vertical and horizontal directions, and the ear 20 is located around the product region 2 and has a rectangular frame shape in plan view.
As shown in FIGS. 1, 2 (a) and 2 (b), the ceramic wiring substrate 1 is formed by laminating a plurality of green sheets 16 to 19 and having a front surface 3 and a back surface 4. It is a laminate having a conductor layer 12, a conductor layer 14 provided on the back surface 4, and conductor layers 13 and 15 having a predetermined pattern provided between green sheets 16-19. The conductor layers 12 to 15 are unfired conductors made of the conductive paste. 1 and 2 (a) and 2 (b), reference numeral 5 shown by a broken line is an imaginary planned cutting surface.

As shown in FIG. 1, the conductor layer 12 on the surface 3 side is formed along the entire surface 3 for each unit ceramic wiring substrate 6 and the product region 2 side of the ear portion 20.
Moreover, as shown in FIGS. 1 and 2B, the intersection of the scheduled cutting surfaces 5 that divide the adjacent unit ceramic wiring boards 6, 6, and the planned cutting surface 5 that divides the wiring boards 6, 6. A through-hole 10 having a circular cross section that passes through between the front surface 3 and the back surface 4 is formed at the intersection of the cutting plane 5 that divides the wiring board 6 and the ear portion 20. A cylindrical through-hole conductor 11 made of an unfired conductor made of the conductive paste is formed along the inner wall surface of the hole 10. The through-hole conductor 11 is connected to the conductor layer 12 on the front surface 3 side, the conductor layer 14 on the back surface 4 side, and the conductor layer 13 in the middle. An unfired via conductor (not shown) made of the conductive paste is formed between the conductor layers 12, 13 and 15. Of these, when the conductor layer 13 is divided later, the conductor layer 13 connects the through-hole conductor 11 having an arc shape having a cross section of about 1/4 and the conductor layer 15 serving as a wiring layer. It is a wiring layer for connection.
Further, the cavity 7 formed for each unit ceramic wiring substrate 6 has a bottom surface 8 that is rectangular in plan view and four side surfaces 9 that stand up from the periphery of the bottom surface 8. A pair of electrodes (not shown) for individually conducting with a pair of electrodes in an electronic component to be mounted such as a vibrator are formed.

Next, the ceramic substrate 1 for multi-cavity is irradiated with a laser along each scheduled cutting surface 5, so that the unit ceramic wiring substrates 6, 6 and between the wiring substrate 6 and the ear 20 are formed. The process of forming the division | segmentation groove | channel (24) for individualization was performed.
In the graph of FIG. 3, the characteristics of the YVO ₄ laser used in the present invention, the properties of YAG laser of the comparative example, shown schematically. As shown in FIG. 3, the power curves of the YVO ₄ laser and the YAG laser each draw a curve having a peak, and the YVO ₄ laser has a peak at a high repetition frequency of about 50 KHz, The YAG laser is at a low repetition frequency of about 10 KHz at the peak. Therefore, even when the laser power (W) of the two types of lasers is the same, the YVO ₄ laser obtains a high repetition frequency and a high output so that the energy is low, whereas the YAG laser has a low repetition frequency and Since a high output is obtained, energy is increased (see Formula 1).

(Equation 1)
Energy (J) = Output (W) / Repetition frequency (Hz)

For example, assuming that the laser output is 10 W, in the case of a YVO ₄ laser, 10 W is output in a high repetition frequency region of about 50 KHz, and thus the obtained energy is as low as 0.2 mJ. On the other hand, in the case of a YAG laser, since 10 W is output in a low repetition frequency region of about 10 KHz, the obtained energy is higher than that of a 1 mJ and YVO ₄ laser.
That is, irradiation is performed from the surface 3 side including the conductor layer 12 along the thickness direction of the green sheets 16 to 19, and irradiation is continuously performed along the surface 3. When a YVO ₄ laser is used in forming 24), relatively little energy is required compared to a YAG laser, and therefore, thermal influence on the irradiated conductor layer 12 and the green sheet 16 can be suppressed. In addition, since a high repetition frequency can be obtained, grooving can be performed at a high speed. Therefore, it is possible to efficiently form a dividing groove having a relatively narrow groove width, a long and deep cross section, and a relatively smooth inner wall surface at a high speed.
As shown in the graph of FIG. 3, the pulse width of the YVO ₄ laser is generally smaller than the pulse width of the YAG laser.

FIG. 4 shows the YVO ₄ laser 22 according to the present invention, in which the multi-piece ceramic wiring board 1 is cut along the planned cutting surface 5 along the thickness direction of the green sheets 16 to from the surface 3 side including the conductor layer 12. Or it is the schematic which shows the process of irradiating the YAG laser 23 of a comparative example, and forming a division | segmentation groove | channel.
As shown in FIG. 4, the YVO ₄ laser 22 stimulated and amplified by a laser oscillator (not shown) including a laser medium made of yttrium vanadate (YVO ₄ ) is formed with a conductive layer 12 by a condenser lens 21 as shown in FIG. Focusing on the vicinity of the surface 3 of the green sheet 16 that has been irradiated, irradiation is performed along the thickness direction of the green sheet 16 and the like, and as the laser oscillator moves, along the planned cutting plane 5 as shown in FIG. Irradiated along the depth direction. The YVO ₄ laser 22 that was specifically irradiated was a second harmonic YVO ₄ laser 22 having a frequency (half wavelength) that is twice that of the fundamental wave with a repetition frequency of 50 KHz.
On the other hand, the YAG laser 23 of the comparative example is also irradiated with the same output as that of the YVO ₄ laser 22 using a dedicated laser oscillator, and has a relatively slower moving speed than that of the YVO ₄ laser 22. Irradiation was made along the planned cutting surface 5.

As shown in FIG. 5, by the irradiation with the YVO ₄ laser 22 according to the present invention, the dividing groove 24 having a relatively narrow groove width and a vertically elongated cross-section V-shape is formed along the planned cutting surface 5. That is, the conductor layer 12 on the surface 3 is divided substantially symmetrically in the vicinity of the planned cutting surface 5, and the green sheets 16 and 17 and the conductor layer 13 located immediately below the conductor layer 12 are also divided substantially symmetrically by the dividing grooves 24. In addition, the pair of inner wall surfaces 25 in the dividing groove 24 was relatively smooth.
On the other hand, as shown in FIG. 6, by the irradiation with the YAG laser 23 of the comparative example, a split groove 26 having a relatively wide groove width and a vertically short cross section was formed along the planned cutting surface 5. That is, the conductor layer 12 on the surface 3 is divided into left and right with a loss portion 27 having a predetermined width in the vicinity of the planned cutting surface 5, and the green sheets 16 and 17 and the conductor layer 13 positioned immediately below are also divided into the divided grooves. 26, and a partial separation 29 of the conductor layer 13 occurred near the end of the conductor layer 13 exposed in the middle of the pair of inner wall surfaces 28 in the dividing groove 26. .

When grooving was performed by irradiating the YVO ₄ laser 22 as in the present invention, the divided grooves 24 having a narrow opening and a long and deep vertical shape could be formed. As a result, the green sheets 16 to 19 and the conductor layers 12 to 15 are fired, and the surfaces of the conductor layers 12 and 15 exposed to the outside are subjected to Ni plating and Au plating. Each wiring board 6 was separated into individual pieces. As a result, the wiring board 6 having a required shape and dimensions could be obtained. Further, according to the dividing groove 24, in the unit ceramic wiring substrate 6, the conductor layer 12 having a predetermined width remains in the shape of a rectangular frame on the surface 3 surrounding the opening of the cavity 7. The metal frame can be securely brazed via Therefore, the cavity 7 can be reliably sealed by seam welding a metal lid for sealing the cavity 7 on which the electronic component is mounted on the metal frame. Further, since the end portion of the inner conductor layer 13 is positioned near the inner wall surface 25 of the dividing groove 24 without peeling, the divided through-hole conductor 11 and the inner conductor layer 15 are stable. It was also possible to guarantee continuity.

On the other hand, when the groove was cut by irradiating with the YAG laser 23 of the comparative example, the dividing groove 26 having a wide opening and a short length was formed. As a result, the green sheets 16 to 19 and the conductor layers 12 to 15 were fired and subjected to the same plating, and then separated into individual unit ceramic wiring boards 6 along the dividing grooves 26.
As a result, the unit ceramic wiring board 6 that does not have the required shape and dimensions was included. Further, according to the dividing groove 26, in each unit ceramic wiring board 6, the narrow conductor layer 12 is left on the surface 3 surrounding the opening of the cavity 7 with the lost portion 27 on the outer peripheral side left, It has been difficult to firmly braze the metal frame onto the conductor layer 12 via a brazing material. Therefore, even if the metal lid for sealing the cavity 7 on which the electronic component is mounted on the metal frame is seam welded, the sealing of the cavity 7 may become unstable. In addition, the inner wall 28 of the dividing groove 26 has a separation 29 in the vicinity of the end of the inner conductor layer 13, so that the conduction between the divided through-hole conductor 11 and the inner conductor layer 15 is unstable. There was a case.

As described above, the YVO ₄ laser 22 is irradiated to the grooving process in the step of forming the divided grooves for separating the multi-piece ceramic wiring board 1 into a plurality of unit ceramic wiring boards 6. According to the method of the present invention, as compared with the case of irradiating the YAG laser 23 of the comparative example, a relatively high repetition frequency can be obtained, and the vertically elongated section V-shaped dividing groove 24 can be formed at a high speed with less energy. I was able to. As a result, the box-shaped unit ceramic wiring board 6 singulated along the dividing grooves 24 has high accuracy in shape and size, the conductor layer 12 having a required width remains on the surface 3, and Stable conduction between the through-hole conductor 11 and the inner conductor layers 13 and 15 could be easily ensured.
Therefore, it was found that the method for manufacturing the ceramic wiring board 1 according to the present invention has an advantage over the method of the comparative example.

The present invention is not limited to the embodiment described above.
For example, a ceramic wiring board that is an object of the present invention includes a single-layer green sheet and a conductor layer formed on the surface of the green sheet, and the single-layer ceramic layer and the surface of the ceramic layer after firing. It may be a conductor layer formed in the above.
In addition, the ceramic wiring board that is the subject of the present invention has a (unit) ceramic wiring board that is a single product in a plan view, and an ear portion that surrounds the ceramic wiring board, and is divided along the boundary between the two. The form which forms is also included.
Furthermore, the green sheet may be a glass-ceramic that is a kind of low-temperature fired ceramic after firing at a predetermined temperature.
The YVO ₄ laser may be a third harmonic or fourth harmonic YVO ₄ laser.
Furthermore, the repetition frequency of the YVO ₄ laser is appropriately selected between 20 and 250 KHz.
In addition, the irradiation of the YVO ₄ laser is not limited to the conductive layer formed on the surface of the single-layer green sheet or the green sheet laminate in which a plurality of green sheets are laminated, but the back surface of the green sheet. Alternatively, laser irradiation may be performed symmetrically from the back side of the green sheet laminate.

  According to the present invention, a plurality of ceramic wiring boards having a predetermined size and shape, or having a conductor layer having a predetermined width formed on the surface surrounding the opening of the cavity are also provided, and between these wiring boards. It has become possible to stably and reliably provide a method for manufacturing a multi-piece ceramic wiring board in which divided grooves are formed.

1 …………… Ceramic wiring board (ceramic wiring board)
3 …………… Surface 12 ………… Conductive layer 16-19… Green sheet 22 ………… YVO ₄ laser 24 ………… Dividing groove

Claims (3)

A method for producing a ceramic wiring board, comprising dividing a conductor layer formed at least on the surface of a ceramic layer and having a dividing groove along the surface,
The conductor layer formed on the surface of the ceramic green sheet is irradiated with a YVO ₄ laser along the thickness direction of the conductor layer and the green sheet located below the conductor layer, and the surface of the green sheet is irradiated Forming a dividing groove along the surface by continuously irradiating along the surface,
A method of manufacturing a ceramic wiring board. The YVO ₄ laser is a second to fourth harmonic YVO ₄ laser,
The method for manufacturing a ceramic wiring board according to claim 1. The repetition frequency of the YVO ₄ laser is 20 to 250 KHz.
The method of manufacturing a ceramic wiring board according to claim 1 or 2, wherein

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