JP5300698B2 - Wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wiring board capable of suppressing peeling of a through conductor, electrically connecting a plurality of wiring conductors on an upper and a lower surfaces of an insulating layer, from an inner side face of a through hole. <P>SOLUTION: The wiring board includes the insulating layer 1 which is made of a ceramic sintered body and has the through hole 3, the inner side face of the through hole 3 being formed of a melting modified layer 1a formed by partially melting and then hardening the ceramic sintered body; the wiring conductors 2 formed on the upper and the lower surfaces of the insulating layer 1; and the through conductor 4 bonded to the inner side face of the through hole 3 and electrically connecting the wiring conductors 2 on the upper and the lower surfaces of the insulating layer 1 to each other, wherein the through conductor 4 has a contact layer 4a bonded to a surface of the melting modified layer 1a and a conductor layer 4b bonded to a surface of the contact layer 4a, and a cut A forming a partial gap between the melting modified layer 1a and conductor layer 4b is formed in the contact layer 4a. Thermal stress acting on the through conductor 4 is absorbed at the part of the cut A to suppress the peeling of the through conductor 4 due to the thermal stress. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to an insulating layer having a through-hole penetrating in the thickness direction, a wiring conductor formed on the upper and lower surfaces of the insulating layer, and a wiring conductor on the inner and lower surfaces of the through-hole, It is related with a wiring board provided with a penetration conductor which connects electrically.

  Conventionally, as a wiring board used for mounting electronic parts, etc., an insulating layer made of a ceramic sintered body and having a wiring conductor formed on the upper surface and the lower surface, a through hole penetrating the insulating layer in the thickness direction, and a through hole A thing provided with the penetration conductor (via conductor) attached to the inner surface of a hole is used. The wiring conductors on the upper and lower surfaces of the insulating layer have portions that are vertically overlapped at the positions where the through holes are formed, and these portions are electrically connected vertically via the through conductors.

  In such a wiring board, for example, an electrode of an electronic component or a probe for performing an electrical inspection of the electronic component is connected to the wiring conductor on the upper surface of the insulating layer, and the wiring conductor on the lower surface is connected to an external electric circuit board such as a circuit board. Is done. The electronic component is electrically connected to an external electric circuit via the wiring conductor on the upper surface of the insulating layer, the through conductor, and the wiring conductor on the lower surface of the insulating layer, and transmission / reception of signals and electrical connection to the electronic component are performed. Inspects are performed.

  The through conductor forms a through hole having a circular opening or the like by laser processing at a predetermined position of an insulating layer made of a ceramic sintered body, and adheres an adhesion layer to the inner surface of the through hole by a sputtering method, and then It is formed by depositing a conductor layer on the surface of the adhesion layer by plating. The adhesion layer is for enabling the conductor layer to be deposited by plating on the inner surface of the through hole of the insulating layer made of an insulating material.

  Since the ceramic sintered body is melted with laser processing, a layer (melt-modified layer) solidified after the ceramic sintered body is partially melted is formed on the inner surface of the through hole of the insulating layer. Therefore, actual peeling of the through conductor is likely to occur at the interface between the adhesion layer of the through conductor and the melt-modified layer.

JP-A-1-155680 JP-A-10-275874

  However, in such a wiring board, a thermal stress is generated due to a difference in thermal expansion coefficient between the insulating layer and the through conductor, and there is a problem that the through conductor may be peeled off from the inner surface of the through hole due to the thermal stress. there were.

  In particular, in recent years, the number of wiring conductors to which probes are connected at the same time tends to increase in response to the increase in the density of electrodes of electronic components, and the heating time for the wiring board has increased accordingly. Peeling of the through conductor due to such thermal stress is likely to occur.

  The present invention has been completed in view of the above-described problems of the prior art, and its purpose is to peel off the through conductors that electrically connect the plurality of wiring conductors on the upper and lower surfaces of the insulating layer from the inner surface of the through hole. An object of the present invention is to provide a wiring board capable of effectively suppressing this.

  The wiring board of the present invention comprises a ceramic sintered body, has a through-hole penetrating in the thickness direction, and the inner surface of the through-hole is solidified after the ceramic sintered body is partially melted. An insulating layer as a modified layer; wiring conductors formed on the top and bottom surfaces of the insulating layer; and the wiring conductors on the top surface of the insulating layer and the wirings on the bottom surface, which are attached to the inner surface of the through hole A wiring board comprising a through conductor that electrically connects a conductor, wherein the through conductor is adhered to the surface of the melt-modified layer and the surface of the adhesion layer. The adhesive layer is characterized in that a cut is formed in the adhesion layer so as to create a partial gap between the melt-modified layer and the conductor layer.

  The wiring board according to the present invention is characterized in that, in the above configuration, a recess is formed on a surface of the melt-modified layer, and a cut of the adhesion layer is formed corresponding to the recess. It is.

  Further, the wiring board according to the present invention is characterized in that, in the above configuration, the number of the cuts is larger than the upper and lower end portions in the central portion in the depth direction of the through hole.

  According to the wiring board of the present invention, the through conductor is composed of an adhesion layer deposited on the surface of the melt-modified layer and a conductor layer deposited on the surface of the adhesion-modified layer. Since a cut that creates a partial gap between the layer and the conductor layer is formed, it is assumed that thermal stress caused by the difference in thermal expansion coefficient between the through conductor and the insulating layer has occurred. However, the thermal stress can be absorbed by the expansion and contraction of the adhesion layer at the portion adjacent to the cut. Therefore, peeling of the through conductor due to thermal stress can be effectively suppressed. Therefore, it is possible to provide a wiring board that can effectively prevent the through conductors that electrically connect the plurality of wiring conductors on the upper and lower surfaces of the insulating layer from being peeled off from the inner surface of the through hole.

  Further, according to the wiring board of the present invention, in the above configuration, when the recess is formed on the surface of the melt-modified layer, and the cut of the adhesion layer is formed corresponding to the recess, the melt reforming is performed. In the same way, thermal stress can be absorbed also in the vicinity of the concave portion, corresponding to the absorption of thermal stress in the cut portion. Therefore, peeling of the through conductor due to thermal stress can be more effectively suppressed.

  Further, the wiring board according to the present invention has a thermal expansion coefficient between the through conductor and the insulating layer when the number of cuts in the adhesion layer is larger than the upper and lower end portions in the central portion in the depth direction of the through hole. In the central portion where the thermal stress due to the difference tends to concentrate and increase from the upper and lower end sides, the thermal stress can be absorbed more effectively and peeling of the through conductor can be suppressed.

(A) is a top view which shows an example of embodiment of the wiring board of this invention, (b) is sectional drawing in the AA of (a). It is principal part sectional drawing which expands and shows the through-hole part of the wiring board shown in FIG. FIG. 3 is a main part enlarged cross-sectional view (perspective view) schematically showing the main part in the through hole part of FIG. 2 further enlarged. It is a principal part enlarged side view (perspective view) which shows an example of the surface of the contact | adherence layer of the wiring board shown in FIGS.

  The wiring board of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1A is a top view showing an example of an embodiment of a wiring board according to the present invention, and FIG. 1B is a cross-sectional view taken along the line AA in FIG. 2 is an enlarged cross-sectional view of the main part showing the through-hole portion of the wiring board shown in FIG. 1, and FIG. 3 is an enlarged main-section showing the main part in the through-hole part of FIG. It is a figure (perspective view). 1 to 3, 1 is an insulating layer, 2 is a wiring conductor, 3 is a through-hole, and 4 is a conductive conductor composed of an adhesion layer 4a and a conductor layer 4b.

  The insulating layer 1 is composed of an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite sintered body, a glass ceramic sintered body, crystallized glass in which crystal components are precipitated in a glass base material, mica, or titanic acid. It is made of a ceramic material such as a ceramic material (so-called machinable ceramics), which is made of a microcrystalline sintered body such as aluminum, and can be machined substantially as accurately as a metal material.

  If the insulating layer 1 is made of, for example, an aluminum oxide sintered body, it can be manufactured as follows. That is, a ceramic green sheet is formed by forming a slurry prepared by adding and mixing an appropriate organic binder and organic solvent to raw material powders such as aluminum oxide and silicon oxide into a sheet shape by a sheet forming technique such as a doctor blade method or a lip coater method. After that, the ceramic green sheet can be made into an appropriate shape and size by cutting or punching and fired at a temperature of about 1300 to 1500 ° C.

  The insulating layer 1 has, for example, a square plate shape or a disk shape, and has, for example, an electronic component (not shown) for mounting or electrical check mounted on the upper surface (electrically and mechanically connecting the electronic component to the wiring board). Then, it is used as a part for mounting to make an electronic device, or for temporarily placing an electronic component for electrical check). Examples of the electronic component 7 include semiconductor integrated circuit elements such as ICs and LSIs, and semiconductor elements including optical semiconductor elements such as LEDs (light emitting diodes), PDs (photodiodes), CCDs (charge coupled devices), surface acoustic wave elements, and crystals. Examples include various electronic components 7 such as piezoelectric elements such as vibrators, capacitive elements, resistors, and micromachines (so-called MEMS elements) in which a minute electromechanical mechanism is formed on the surface of a semiconductor substrate.

  A wiring conductor 2 is formed on each of the upper and lower surfaces of the insulating layer 1. The wiring conductor 2 is electrically connected to an electronic component, for example, and functions as a terminal for connecting a probe for transmitting / receiving a signal to the electronic component and performing an electrical check on the electronic component. The wiring conductors 2 on the upper and lower surfaces of the insulating layer 1 are electrically connected to each other through a through conductor 4 formed on the inner surface of the through hole 3 that penetrates the insulating layer 1 in the thickness direction.

  The electrical connection between the wiring conductor 2 and the electronic component is performed, for example, by joining an electrode (not shown) of the electronic component to a predetermined portion of the wiring conductor 2 via a conductive connecting material such as solder. In this case, solder or the like is joined from the surface of the wiring conductor 2 to the surface of the through conductor 4 in the through hole 3 to increase the solder joint area and improve the reliability of electrical connection. May be.

  Although FIG. 2 shows the wiring conductor 2 on the upper surface side of the insulating layer 1, the wiring conductor 2 is formed in a predetermined pattern on the lower surface side of the insulating layer 1 as well as the upper surface side. . The pattern of the wiring conductor 2 on the lower surface side may be the same as or different from the upper surface side.

  The through hole 3 is formed by subjecting the insulating layer 1 made of a ceramic sintered body to drilling processing (laser processing) by laser light irradiation. Since the through hole 3 is formed by drilling the insulating layer 1 made of a ceramic sintered body (not in the state of the unfired ceramic green sheet), the dimensional accuracy due to shrinkage during firing is improved. Unaffected by decline. Therefore, in this wiring board, the positional accuracy of the through hole 3 in the insulating layer 1 is high.

  During this laser processing, the inner surface of the through hole 3 is heated by the laser beam and partially melted, and then cooled (natural cooling or the like) to solidify. Therefore, the inner surface of the through-hole 3 in the insulating layer 1 is a melt-modified layer 1a that is solidified after the ceramic sintered body is partially melted.

  In the melt-modified layer 1a, a glass component such as silicate glass is layered at the interface with the insulating layer 1 or the interface with the adhesion layer 4a. Further, particles grown by recrystallization of aluminum oxide or silicon oxide are dispersed in the glass layer.

  The through-hole 3 has, for example, a circular shape with a diameter of about 300 μm to 700 μm, and the through conductor 4 is formed by sequentially depositing the adhesion layer 4 a and the conductor layer 4 b on the inner side surface.

  The adhesion layer 4a and the conductor layer 4b are made of, for example, a metal material such as copper, silver, palladium, gold, platinum, aluminum, chromium, nickel, cobalt, titanium, tungsten, molybdenum, manganese, or an alloy material of these metal materials. .

  The adhesion layer 4a is for attaching the conductor layer 4b to the inner side surface of the through hole 3, and the conductor layer 4b is for connecting the wiring conductors 2 on the upper and lower surfaces of the insulating layer 1 with low resistance. is there.

  The adhesion layer 4a is attached to the inner surface of the through hole 3 by a sputtering method. The metal material for forming the adhesion layer 4a is particularly a metal material such as titanium or chromium that can be firmly attached to the melt-modified layer 1a (silicate glass or the like) of the through hole 3 by a sputtering method. Is suitable. What is necessary is just to set the thickness of such an adhesion layer 4a to about 0.05-5 micrometers.

  Further, the adhesion layer 4a may be composed of a plurality of layers instead of only one layer. For example, first, a sputtering film (not shown) made of titanium having particularly high adhesion to the melt-modified layer 1a is deposited, and then the adhesion to the conductor layer 4b made of a plating layer is good on the surface. A sputtered film (not shown) made of copper may be deposited, and the adhesion layer 4a may be formed of these sputtered titanium and copper films.

  Since the conductor layer 4b is for connecting the upper and lower wiring conductors 2 with low electrical resistance, it is formed of a relatively thick plating layer of about 5 to 20 μm, for example. Further, the metal material for forming the conductor layer 4b is preferably made of a metal material such as copper, silver, gold, etc., which can be easily deposited by plating and has low electric resistance. In view of the suppression of copper and the like, copper is particularly preferable. In addition, the conductor layer 4b is copper plated in consideration of oxidation of a copper plating layer (not shown) and solder wettability when solder is bonded to the surface of the through conductor 4 as described above during mounting. It is preferable that a nickel and gold plating layer (not shown) be sequentially deposited on the surface of the layer.

  The conductor layer 4b is preferably applied by an electrolytic plating method in consideration of suppression of the spread of the metal material during plating, productivity, and the like. For example, if the conductor layer 4b is formed of a copper plating layer, a nickel plating layer, and a gold plating layer sequentially deposited on the surface of the adhesion layer 4a, the following may be performed.

  First, the insulating layer 1 on which the adhesion layer 4a is deposited is immersed in an electrolytic copper plating solution mainly composed of copper sulfate or copper cyanide, and a plating current is supplied to the adhesion layer 4a via the wiring conductor 2. Then, a copper plating layer is deposited on the surface of the adhesion layer 4a. Then, the insulating layer 1 in which the copper plating layer is deposited on the adhesion layer 4a is sequentially immersed in an electrolytic nickel plating solution mainly containing nickel sulfate and an electrolytic gold plating solution mainly containing potassium gold cyanide. At the same time, a current for plating is supplied as in the case of the copper plating layer, and the nickel plating layer and the gold plating layer are sequentially deposited on the surface of the copper plating layer. Through the above steps, the conductor layer 4b having the above-described plating layer structure can be deposited on the surface of the adhesion layer 4a.

  In addition, said wiring conductor 2 can also be formed by the same method using the material similar to these contact | adherence layer 4a and the conductor layer 4b. That is, first, an adhesion layer (no symbol) is applied to predetermined portions of the upper and lower surfaces of the insulating layer 1 by the same material and method as those for forming the adhesion layer 4a in the through hole 3, and then the adhesion layer is adhered. If a conductor layer (no symbol) is deposited on the surface of the insulating layer 1 by using the same material and method as those for forming the conductor layer 4b of the through hole 3, wiring is performed in a predetermined pattern on the upper and lower surfaces of the insulating layer 1. The conductor 2 can be formed.

  In such a wiring board, for example, an electrode of an electronic component (not shown) and a probe (not shown) for performing an electrical inspection of the electronic component are connected to the wiring conductor 2 on the upper surface of the insulating layer 1. The wiring conductor 2 is connected to an external electric circuit board (not shown) such as a circuit board. The electronic component is electrically connected to an external electric circuit via the wiring conductor 2 on the upper surface of the insulating layer 1, the through conductor 4, and the wiring conductor 2 on the lower surface of the insulating layer 1, and transmission and reception of signals, An electrical check for electronic components is performed. The electrical check for the electronic component is, for example, an inspection of whether or not the integrated circuit of the semiconductor integrated circuit element operates normally. In this case, in order to collectively inspect a plurality of semiconductor integrated circuit elements (not shown) formed on a semiconductor substrate (silicon wafer or the like) before cutting into individual pieces, for example, FIG. A wiring board as shown in FIG. 5 is used in which a wiring board is arranged on a mother board having the same size as a semiconductor substrate. In this case, the wiring board (wiring board arranged in large numbers) can be used as a so-called probe card.

  In the wiring board of the present invention, the through conductor 4 is composed of the adhesion layer 4a and the conductor layer 4b as described above, and a partial gap is formed in the adhesion layer 4a between the melt-modified layer 1a and the conductor layer 4b. The resulting cut A is formed. Since such a cut A is formed, even if a thermal stress due to the difference in thermal expansion coefficient between the through conductor 4 and the insulating layer 1 is generated, the thermal stress is reduced by the adhesion layer 4a. Can be absorbed by expanding and contracting at a portion adjacent to the cut A. Therefore, peeling of the through conductor 4 due to thermal stress can be effectively suppressed.

  According to the wiring board of the present invention, in the above configuration, the recess B is formed on the surface of the melt-modified layer 1a, and the cut A of the melt-modified layer 1a is formed corresponding to the recess B. If so, the thermal stress can be similarly absorbed on the side of the melt-modified layer 1a corresponding to the absorption of the thermal stress in the portion of the cut A. Therefore, peeling of the through conductor 4 due to thermal stress can be suppressed more effectively. Therefore, it is possible to effectively prevent the through conductor 4 that electrically connects the wiring conductors 2 on the upper and lower surfaces of the insulating layer 1 from being peeled off from the inner surface of the through hole 3 (actually, the surface of the melt-modified layer 1a). It is possible to provide a wiring board capable of satisfying the requirements.

  Such a break A is better when it is only considered to effectively absorb thermal stress as described above, but if it becomes too large, the adhesion layer 4a, the melt-modified layer 1a, and the conductor layer 4b , The bonding strength itself decreases, and the through conductor 4 may be easily peeled off. Therefore, the cut A has a total area when viewed from a direction perpendicular to the surface of the through conductor 4 (as viewed from the side) with respect to the bonding area between the melt-modified layer 1a and the conductor layer 4b. A range of about 5 to 10% is preferable. Each cut A has a size of about 0.1 to 50 μm when viewed from the side, and penetrates the adhesion layer 4a in the thickness direction.

  Further, the shape of the cut A when viewed from the side is an ellipse, an ellipse, a shape in which both end portions in the major axis direction are pointed, a band, or the like. With respect to the shape of the cut A, since the thermal stress tends to act greatly in the length direction of the through conductor 4 in effectively absorbing the thermal stress between the through conductor 4 and the insulating layer 1, the long axis Is preferably an elliptical shape along the length direction of the through conductor 4.

  In the portion where the cut A is formed in the adhesion layer 4a, the cut similar to the cut A (not indicated) also penetrates the conductor layer 4b in part in the thickness direction of the conductor layer 4b or in the thickness direction. It may be formed. Since the cut A of the adhesion layer 4a is sized so that the adhesion layer 4a is limited to a part of the inner surface of the through-hole 3, even if the conductor layer 4b has a cut at such a portion, There is no significant effect on the electrical characteristics such as the electrical resistance of the conductor layer 4b.

  The adhesion layer 4a having such a cut A is, for example, a ceramic that prevents the adhesion of a sputtering film of titanium or the like to be the adhesion layer 4a to the surface of the melt-modified layer 1a when the adhesion layer 4a is applied. Particles (not shown) may be attached to the surface of the melt-modified layer 1a, and then the ceramic particles may be washed away.

  Further, when the through hole 3 is formed in the insulating layer 1 by laser processing, the recess B is formed on the inner surface of the through hole 3 by adjusting the angle and intensity of laser light irradiation, the number of shots, and the like. The cut A can also be formed in the adhesion layer 4a by a method in which the adhesion layer 4a is not deposited on the recess B. For example, if the intensity of the laser light is increased and the number of shots is adjusted to increase, the molten glass component adheres to the inner surface of the through-hole 3 after scattering, and the inner surface becomes a so-called sacrificial shape. A recess B is formed in the quality layer 1a.

  In this case, the recess B is formed on the surface of the melt-modified layer 1a, and the cut A of the adhesion layer 4a is formed corresponding to the recess B. In such a case, the thermal stress is absorbed also in the vicinity of the recess B in the same manner as described above, corresponding to the absorption of the thermal stress in the portion of the cut A on the side of the melt-modified layer 1a. Can do. Therefore, peeling of the through conductor 4 due to thermal stress can be suppressed more effectively.

  For example, the recess B has the same shape as the cut A when viewed from the side (opening shape at the interface with the adhesion layer 4a), and the interface with the adhesion layer 4a (adhesion of the adhesion layer 4a) of the melt-modified layer 1a. From the exposed surface) to the inside of the melt-modified layer 3. When the recess B penetrates the melt-modified layer 1a in the thickness direction, it is possible to obtain a greater effect of absorbing the thermal stress as described above.

  However, even if the concave portion B does not penetrate the melt-modified layer 1a in the thickness direction, at least as long as the concave portion B is formed from the interface with the adhesion layer 4a as described above (the opening portion of the concave portion B at this interface). If there is), the cut A can be formed in the adhesion layer 4a.

  Further, the recess B may have the same cross-section (a cross section in a direction perpendicular to the depth direction of the recess B) from the interface with the adhesion layer 4a toward the inside of the melt-modified layer 1a, and becomes narrower gradually. However, in order to suppress mechanical destruction such as cracks in the melt-modified layer 1a, those that are gradually narrowed are preferable.

  Note that the recess B does not necessarily have to have all of the openings at the interface with the adhesion layer 4a connected to the cut A, and a part of the opening may be blocked by the adhesion layer 4a.

  Further, the wiring board of the present invention has the above-described configuration, for example, as shown in FIG. 4, when the cut line A of the adhesion layer 4 a is larger than the upper and lower end portions in the central portion in the depth direction of the through hole 3. In the central portion where the thermal stress due to the difference in thermal expansion coefficient between the through conductor 4 and the insulating layer 1 tends to concentrate and increase from the upper and lower end side, the thermal stress is absorbed more effectively, and the through conductor 4 peeling can be suppressed. FIG. 4 is an enlarged side view (perspective view) of a main part showing an example of the surface of the adhesion layer 4a of the wiring board shown in FIGS. 4, parts similar to those in FIGS. 1 to 3 are denoted by the same reference numerals. In FIG. 4, a part of the adhesion layer 4a is shown as a cross section.

  In this case, since the cut A is collectively formed in the adhesion layer 4a by the method as described above, the shape and dimensions thereof are the same, and when the cut A is viewed from the side according to the number of the cuts A. There is a tendency for the sum of the areas to change. Therefore, by increasing or decreasing the number of cuts A, the area of the cut A when viewed from the side can be increased or decreased. Accordingly, when the cut A is larger than the upper and lower end portions in the central portion in the depth direction of the through-hole 3, the total area of the cut A when viewed from the side is larger than the upper and lower end portions in the central portion. And can absorb the thermal stress more effectively as described above.

  Regarding the cut A, the ratio of the center portion in the depth direction of the through-hole 3 is larger than the upper and lower end portions, for example, the thickness of the contact layer 4a made of a sputtering film of titanium and copper is about 0.3 to 3 μm. If the conductor layer 4b is made of a copper plating layer and has a thickness of about 5 to 10 μm, the diameter of the through hole 3 is about 300 to 700 μm, and the depth is about 1500 to 3000 μm, the central portion The upper and lower end portions may be set to about 1.5 to 3 times.

  A through-hole having a diameter of about 680 μm and a length of about 2500 μm is formed by laser processing on a ceramic substrate made of an aluminum oxide sintered body, and titanium and copper having a thickness of about 3 μm are sequentially formed on the inner surface of the through-hole. A through conductor was formed by sequentially depositing an adhesive layer and a conductor layer made of copper having a thickness of about 10 μm by sputtering and electroless plating, respectively, and 100 wiring boards of the example were produced. .

  On the inner side surface of the through hole, a concave portion was formed by adjusting the irradiation intensity of the laser beam at the time of laser processing, and a cut was formed in the adhesion layer according to the concave portion. The cuts were substantially elliptical when viewed from the side, had a major axis dimension of about 10 to 20 μm and a minor axis dimension of about 2 to 6 μm. Such cuts were formed at a ratio of the total area of the surface of the adhesion layer to about 10%. Note that the shape and size of these cuts can be confirmed by extracting two wiring boards before attaching the conductor layer to the surface of the adhesion layer, and cutting them in the length direction of the through hole at the through hole portion. Then, the surface of the adhesion layer was confirmed by visual observation (enlarged 20 to 400 times).

  In addition, as a comparative example, 100 prior art wiring boards without cuts were prepared. As for the wiring board of a comparative example, two pieces were extracted similarly to the case of the said Example, and it confirmed that the cut | interruption was not formed in the contact | adherence layer by visual observation (enlarged 20-400 times).

  About the wiring board of these Examples and the comparative example, after heating to about 300 degreeC, the presence or absence of peeling in a penetration conductor was confirmed visually (enlarged 20-400 times).

  As a result, no peeling occurred in the through conductor in the wiring board of the example, whereas in the wiring board of the comparative example, the two through conductors in one wiring board and in the other wiring board Each of the through conductors was peeled off.

  From the above results, it was possible to confirm the effect of suppressing peeling of the through conductor in the wiring board of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Insulating layer 1a ... Melt modification layer 2 ... Wiring conductor 3 ... Through-hole 4 ... Through-conductor 4a ... Adhesion layer 4b ... Conductor layer A ... Adhesion layer break B ... Recesses of melt-modified layer

Claims (3)

Insulation formed of a ceramic sintered body, having a through hole penetrating in the thickness direction, and an inner surface of the through hole being a melt-modified layer formed by solidifying after the ceramic sintered body is partially melted A layer, a wiring conductor formed on the top and bottom surfaces of the insulating layer, and an inner surface of the through hole, and electrically connecting the wiring conductor on the top surface of the insulating layer and the wiring conductor on the bottom surface A through-conductor, wherein the through-conductor comprises an adhesion layer deposited on the surface of the modified layer, and a conductor layer deposited on the surface of the adhesion layer. A wiring board, wherein a cut is formed in the layer so as to create a partial gap between the melt-modified layer and the conductor layer. The wiring board according to claim 1, wherein a recess is formed on a surface of the melt-modified layer, and a cut of the adhesion layer is formed corresponding to the recess. The wiring board according to claim 1, wherein the number of the cuts is larger than the upper and lower end portions in a central portion in the depth direction of the through hole.

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