JP3940589B2 - Manufacturing method of ceramic wiring board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method of manufacturing a ceramic wiring board having a thick film circuit and a metallized wiring conductor and on which electronic components such as semiconductor elements are mounted. Specifically, the ceramic mother board is partitioned by dividing grooves. The present invention relates to a method for manufacturing a ceramic wiring board in which a metallized wiring conductor is formed on the upper surface of a quadrangular region and a thick film circuit is formed on the lower surface.
[0002]
[Prior art]
Conventionally, as a ceramic wiring board for mounting electronic components such as semiconductor elements such as semiconductor integrated circuit elements and capacitive elements, tungsten, molybdenum, etc. on the upper surface of an insulating base made of an electrical insulator such as an aluminum oxide sintered body A ceramic made by depositing a metallized wiring conductor made of a refractory metal material and a thick film circuit made of copper, lanthanum-boron alloy, tin oxide alloy, etc. A wiring board is known. The metallized wiring conductor and the thick film circuit are usually electrically connected via an internal wiring layer of an insulating base.
[0003]
By mounting electronic components on the upper surface of the insulating substrate and connecting the electrodes to the metallized wiring conductor via solder or bonding wires, an electric circuit is formed by the electronic component / metalized wiring conductor and the thick film circuit. Accordingly, the electronic component is sealed with a resin or a lid to complete an electronic device as a product.
[0004]
The metallized wiring conductor functions as a main conductive path for connecting the electrodes of electronic components to the thick film circuit and leading out to the outside. The thick film circuit is a resistor, low electric resistance circuit / capacitance in the above electric circuit. Functions as a circuit element.
[0005]
In this case, the metallized wiring conductor is coated with a plated metal layer of nickel, copper, gold or the like in order to prevent oxidative corrosion of the metallized wiring conductor and to reliably and easily connect the solder and bonding wires.
[0006]
In addition, the thick film circuit is made of a material that easily oxidizes and corrodes, such as copper and tin oxide. Therefore, as with the metallized wiring conductor, it is necessary to apply a coating layer to prevent oxidation. When the plated metal layer is deposited, the electrical characteristics of the thick film circuit deviate from a predetermined value, so that it is usually coated with a protective glass layer and a coating layer made of an organic resin that covers the protective glass layer. Yes. This protective glass layer is made of glass such as boron oxide glass, for example, and is formed by applying a glass paste so as to cover the entire surface of the thick film circuit, and processing and baking at about 600 to 650 ° C. The Further, as the organic resin for the coating layer, generally, an ultraviolet curable epoxy resin or a thermosetting epoxy resin is used.
[0007]
In general, in order to facilitate the handling of such a ceramic wiring board, a dummy ear portion is provided in a portion surrounding the outside of a rectangular region that is a product, and the dummy ear portion and a center that is a product are provided. The dummy ear is divided from the ceramic mother substrate along the dividing groove after completing a predetermined process such as mounting of electronic components. Is removed.
[0008]
Such a ceramic wiring board is manufactured as follows, for example.
[0009]
First, a ceramic green sheet to be a ceramic mother board is prepared, and at least a lower surface thereof is formed with a notch that becomes a dividing groove that divides the central portion of the ceramic green sheet into a square shape as a wiring board region. A metal paste such as tungsten / molybdenum is printed on the upper surface of the region, and then fired at a high temperature to obtain a ceramic mother substrate having a metallized wiring conductor formed on the upper surface.
[0010]
Next, a metal paste such as copper, lanthanum-boron or the like is printed and applied to the lower surface of the rectangular region of the ceramic mother substrate, and heat treated at a temperature lower than the above firing temperature to form a thick film on the lower surface of the insulating substrate. Form a circuit.
[0011]
Next, a glass paste such as boron oxide glass is printed on the thick film circuit, and the thick film circuit is covered with a protective glass layer by firing at a temperature lower than the temperature of the heat treatment when forming the thick film circuit. Further, this protective glass layer is covered with a coating layer made of an organic resin such as an epoxy resin, and finally a plated metal layer is deposited only on the metallized wiring conductor, thereby producing a ceramic wiring board.
[0012]
Note that when the plated metal layer is applied to the metallized wiring conductor on the upper surface of the ceramic mother board, the thick film circuit on the lower surface of the ceramic mother board, the protective glass layer covering the thick film circuit, and the coating layer made of organic resin are masked. Covered with tape. This is to prevent the plating metal layer from adhering to the thick film circuit, and the coating glass and organic resin are easily corroded by the acid / alkaline solution. This is to protect the organic resin from the plating solution.
[0013]
[Problems to be solved by the invention]
However, since this conventional ceramic wiring substrate has a dividing groove formed on at least the lower surface thereof, when the plated metal layer is applied to the metallized wiring conductor of the ceramic wiring substrate, the thick film circuit and the thick film circuit are not provided. When a masking tape is applied to the lower surface of the ceramic mother board to cover the protective glass layer and the organic resin coating layer, the masking tape and the ceramic mother board are not in close contact with each other at the part where the dividing grooves are formed. Will occur. For this reason, when the ceramic wiring board is immersed in the plating processing solution or plating solution in this state, these chemical solutions travel along the dividing grooves from the gaps described above and are formed on the masking tape, the ceramic mother substrate, and the ceramic mother substrate. There was a problem that the thick film circuit was corroded and peeled in between the circuit and the thick film circuit.
[0014]
The present invention has been devised in view of the above-mentioned problems in the prior art, and its purpose is to provide a lower surface when a plated metal layer is deposited on the metallized wiring conductor on the upper surface of the ceramic wiring substrate in the ceramic mother substrate. It is an object of the present invention to provide a method for manufacturing a ceramic wiring board that does not cause corrosion, peeling, or the like in the thick film circuit.
[0015]
[Means for Solving the Problems]
Method for producing a ceramic wiring substrate of the present invention comprises at least a step of forming a split groove in a matrix on the lower surface, main Taraizu wiring on the upper surface of the ceramic matrix rectangular regions partitioned by the dividing groove of the substrate of ceramic matrix substrate A step of forming a conductor, a step of forming a thick film circuit on a lower surface of the rectangular region of the ceramic mother substrate, a step of depositing a protective glass layer on the thick film circuit, and a step of reducing the dividing groove. A step of covering with a covering material made of melting point glass, a step of covering the thick film circuit covered with the protective glass layer with a covering layer made of organic resin, and covering almost the entire lower surface of the ceramic mother substrate. Rukoto be provided a step of affixing a masking tape, and a step of depositing a plated metal layer on the metallized wiring conductor of the ceramic matrix substrate stuck the masking tape Te It is an feature.
[0016]
According to the method for manufacturing a ceramic wiring board of the present invention, the divided grooves formed on the outer peripheral portion of the lower surface of the ceramic mother substrate are covered with the coating material made of low melting point glass. The masking tape can be sufficiently adhered to the insulating substrate through a coating material made of low-melting glass, and the plating solution or plating solution can penetrate into the thick film circuit from the part where the peripheral groove is formed. Therefore, it is possible to effectively prevent the occurrence of corrosion / peeling in the thick film circuit.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described in detail with reference to the accompanying drawings.
[0018]
FIG. 1A is a sectional view showing an example of an embodiment of a method for producing a ceramic wiring board according to the present invention, and FIG. 1B is a plan view thereof.
[0019]
In the figure, 1 is a ceramic mother substrate (insulating base), 2 is a metallized wiring conductor deposited on the upper surface of the ceramic mother substrate 1, 3 is a dividing groove formed on the lower surface of the ceramic mother substrate 1, and 4 is a ceramic mother. A thick film circuit deposited on the lower surface of the substrate 1, 5 is a protective glass layer that covers the thick film circuit 4 on the lower surface of the ceramic mother substrate 1, and 6 is a coating made of an organic resin that covers the lower surface of the ceramic mother substrate 1. Is a layer. This ceramic mother substrate 1, metallized wiring conductor 2, dividing groove 3, thick film circuit 4, protective glass layer 5 and coating layer 6 constitute a ceramic wiring substrate 7.
[0020]
The ceramic mother substrate 1 is made of an aluminum oxide sintered body, an aluminum nitride sintered body, a mullite crystalline sintered body, a silicon carbide sintered body, a silicon nitride sintered body, a glass ceramic sintered body, or the like. Made of electrically insulating material. For example, in the case of an aluminum oxide sintered body, a ceramic slurry obtained by adding and mixing an appropriate organic binder and solvent to ceramic raw material powders such as aluminum oxide, silicon oxide, magnesium oxide, and calcium oxide has been conventionally known. The sheet is formed by the doctor blade method, and a ceramic green sheet for the ceramic mother board 1 is obtained by performing an appropriate punching process on the sheet. Then, these ceramic green sheets are stacked one above the other and the appropriate shape and size are obtained. The green body is cut into a green ceramic molded body for the ceramic mother substrate 1 and then the molded body is fired at a temperature of about 1600 ° C. in a reducing atmosphere.
[0021]
The ceramic mother board 1 has a dividing groove 3 formed on at least the lower surface thereof, and the dividing groove 3 defines a square area (wiring board area as a product) 1a at the center, and the square area 1a is defined. The outer peripheral part 1b which is an area | region outside the division | segmentation groove | channel 3 to be used becomes a dummy ear | edge part. Such a dividing groove 3 can be formed by pressing a cutter blade or the like into the lower surface of the ceramic green sheet to be the ceramic mother substrate 1 and providing a cut in a groove shape.
[0022]
Further, a metallized wiring conductor 2 is formed on the upper surface of the rectangular region 1a of the ceramic mother substrate 1.
[0023]
The metallized wiring conductor 2 is connected to an electrode of an electronic component (not shown) mounted on the ceramic wiring substrate 7 and is electrically connected to lead the electrode to the outside or to connect to the thick film circuit 4. Functions as a road.
[0024]
The metallized wiring conductor 2 is made of a metal powder such as tungsten, molybdenum, copper, or silver, and a ceramic green that forms a ceramic mother substrate 1 by using a metal paste obtained by adding and mixing an appropriate organic binder and solvent to the metal powder such as tungsten. It is formed by printing and applying a predetermined pattern on a sheet by a conventionally known screen printing method or the like and firing together with a ceramic green sheet.
[0025]
The metallized wiring conductor 2 has an exposed surface of about 1 to 10 μm in order to improve, for example, the bonding property and bonding property of the brazing material when an electrode of an electronic component is connected via a low melting point brazing material or a bonding wire. It is preferable to deposit a plating metal layer consisting of a nickel plating film having a thickness of about 0.1 to 3 μm and a gold plating film having a thickness of about 0.1 to 3 μm.
[0026]
The plated metal layer composed of the nickel plating layer and the gold plating layer includes, for example, an electroless nickel plating bath (acidic) mainly composed of nickel sulfate and a phosphorus-based or boron-based reducing agent, and potassium cyanide and boron-based. An electroless gold plating bath (alkaline) containing a reducing agent as a main component is prepared, and the ceramic wiring board 7 is sequentially immersed in each plating bath for a predetermined time, whereby a predetermined thickness is formed on the exposed surface of the metallized wiring conductor 2. Is formed on the substrate.
[0027]
A thick film circuit 4 is deposited on the lower surface of the rectangular region 1 a of the ceramic mother substrate 1 so as to be electrically connected to the metallized wiring conductor 2.
[0028]
Such a thick film circuit 4 is made of a resistor powder such as a lanthanum-boron (LaB ₆ ) alloy or tin oxide (SnO ₂ ). If it is made of tin oxide, a resistor paste obtained by adding and mixing an appropriate organic binder and solvent to the tin oxide powder is applied to the lower surface of the rectangular region 1a of the ceramic mother substrate 1, for example, the ceramic mother substrate 1 The ceramic mother is printed and applied in a predetermined pattern so as to be connected to the metallized wiring conductor 2 via an internal wiring (not shown) provided in advance in the interior of the ceramic substrate, and this is heat-treated at a temperature of about 900 ° C. and baked. It is deposited on the lower surface of the substrate 1.
[0029]
The internal wiring for connecting the metallized wiring conductor 2 and the thick film circuit 4 is provided with a through hole in the ceramic green sheet to be the ceramic mother board 1, and the metallized wiring conductor 2 and the surface of the ceramic green sheet and in the through hole. It can be formed by applying and filling a similar metal paste.
[0030]
A protective glass layer 5 is deposited on the surface of the thick film circuit 4. The protective glass layer 5 prevents the thick film circuit 4 from being oxidized. For example, when the thick film circuit 4 is a thick film resistor, the protective glass layer 5 is trimmed when laser trimming is performed on the thick film resistor as described later. It acts to prevent the exposed back surface of parts other than the part from being damaged.
[0031]
Such a protective glass layer 5 is made of, for example, a glass such as boron oxide glass, and a glass paste obtained by adding and mixing a suitable organic binder and liquid to the boron oxide glass powder is used for the entire surface of the thick film resistor. The coating is applied so as to cover the film, and the film is deposited at a temperature of about 600 to 650 ° C. by baking.
[0032]
Further, the thick film circuit 4 covered with the protective glass layer 5 has its trimmed portion exposed from the protective glass layer 5 by adjusting its electric resistance value to a predetermined value by laser trimming. In order to prevent the portion from being oxidized, it is covered with a coating layer 6 made of an organic resin such as an ultraviolet curable resin.
[0033]
The coating layer 6 made of an organic resin is formed of, for example, an ultraviolet curable epoxy resin, and an uncured epoxy resin precursor is mixed with an additive component such as a suitable photopolymerization initiator to form the thick film circuit 4. The thick film circuit 4 and the protective glass layer 5 are coated by printing and coating so as to cover a predetermined place on the lower surface of the ceramic mother substrate 1 and by irradiating it with ultraviolet rays of about 300 mJ / cm ^2. In this way, it is deposited on the lower surface of the ceramic mother substrate 1.
[0034]
In the thick film circuit 4 formed on the lower surface of the ceramic mother board 1, the ceramic wiring board 7 is made of nickel, gold or the like in order to deposit the plated metal layer on the metallized wiring conductor 2 on the upper surface of the ceramic mother board 1 as described above. When immersed in a plating solution or various acid / alkali plating treatment solutions, it is covered with a masking tape (not shown) so as not to come into contact with the plating solution. The masking tape is applied so as to cover almost the entire lower surface of the ceramic mother substrate 1 in order to cover the entire surface of the thick film circuit 4, the protective glass layer 5 and the covering layer 6.
[0035]
Thus, when the coating layer 6 is applied to the lower surface of the ceramic mother substrate 1 and the masking tape is applied, and the plating metal layer is applied to the metallized wiring conductor 2, at least the outer periphery of the lower surface of the ceramic mother substrate 1 is used in the present invention. It is important to cover the dividing groove 3 formed in the part 1b with a covering material 8 made of low melting point glass.
[0036]
Since the dividing groove 3 formed on the outer peripheral portion 1b of the lower surface of the ceramic mother substrate 1 is covered with the coating material 8 made of low melting point glass, the ceramic mother is also formed at the portion where the dividing groove 3 is formed on the outer peripheral portion 1b. A gap formed between the substrate 1 and the masking tape can be eliminated. When the ceramic mother substrate 1 is immersed in a plating solution such as gold or a plating solution such as hydrochloric acid / alkali degreasing solution, the outer peripheral portion 1b Infiltration of the plating solution or the like from the dividing groove 3 into the thick film circuit 4 can be effectively prevented.
[0037]
As a result, it is possible to effectively prevent the penetration of the plating solution or the like into the thick film circuit 4, thereby effectively preventing the thick film circuit 4 from being corroded or peeled off, and the reliability as the ceramic wiring board 7 is excellent. Can be.
[0038]
Here, the covering material 8 that covers the dividing groove 3 formed on the outer peripheral portion 1b of the ceramic mother substrate 1 is made of glass components such as silicic acid-based, boric acid-based, phosphoric acid-based, borosilicate-based materials such as aluminum, sodium, It is formed of a glass composition containing oxides such as lead, potassium, beryllium, and lithium. The covering material 8 made of such a low-melting glass is, for example, a sheet-like material placed on the outer peripheral portion 1b of the ceramic mother board 1 so as to cover the divided grooves 3, and heated and baked to form the ceramic mother board 1. The dividing groove 3 can be covered by being adhered to the outer peripheral portion 1b.
[0039]
Further, the low melting point glass forming the covering material 8 can be firmly attached to the ceramic mother substrate 1 made of an aluminum oxide sintered body or the like, and the protective glass layer 5 is formed when the covering material 8 is fused. In order to prevent melting and to suppress cracks in the ceramic mother substrate 1 due to thermal contraction stress at this time, it is preferable to use lead borosilicate glass that can be baked at less than 600 ° C.
[0040]
Moreover, it is preferable that the coating material 8 is made thin in the outer edge part. This prevents the coating material 8 from peeling off from the edge of the outer edge when stress such as thermal stress is generated between the ceramic mother substrate 1 and the coating material 8 and the stress is increased at the outer edge of the coating material 8. This is because the material 8 can be more firmly attached to the ceramic mother substrate 1.
[0041]
The method for manufacturing a ceramic wiring board according to the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.
[0042]
For example, in the above-described example, the dividing groove 3 is formed only on the lower surface of the ceramic mother substrate 1, but the lower dividing groove 3 is opposed to the dividing groove 3 on the lower surface or to perform a different division. Divided grooves may also be formed on the upper surface of the ceramic mother substrate 1 at different positions.
[0043]
In the above example, only one rectangular region 1a defined by the dividing grooves 3 is formed at the center of the ceramic mother substrate 1. However, this rectangular region 1a is arranged in a vertical and horizontal arrangement. It is also possible to form so-called multi-piece ceramic wiring boards by forming them in a plurality of rectangular wiring board regions, and in this case also, the thick film circuits 4 respectively formed on the lower surfaces of these many wiring board regions are protected. While covering with the glass layer 5 and the coating layer 6, the division | segmentation groove | channel 3 formed in the outer peripheral part 1b should just be coat | covered with the coating | covering material 8 which consists of low melting glass.
[0044]
Further, in the above-described example, the covering material 8 that covers the dividing groove 3 of the outer peripheral portion 1b is shown in an example in which the covering material 8 is covered in correspondence with the dividing groove 3 separately from the rectangular region 1a in the central portion. The dividing groove 3 may be covered by covering the whole 1b with the covering material 8.
[0045]
【The invention's effect】
According to the method for manufacturing a ceramic wiring board of the present invention, the dividing groove formed on the outer periphery of the lower surface of the ceramic mother board and positioned outside the quadrangular region defined by the dividing groove is coated with low melting glass. Since a thick film circuit is formed on the lower surface of the ceramic mother substrate, the protective glass layer and an organic resin that covers the protective glass layer are used to deposit the plated metal layer on the upper metallized wiring conductor. When masking a lower surface having a thick film circuit covered with a coating layer made of a masking tape in the outer peripheral portion of the ceramic mother board, that is, in the dividing groove located outside the rectangular area defined by the dividing groove Can be sufficiently adhered to the insulating substrate through a coating material made of low-melting glass. Since it is possible to prevent the penetration of the membrane circuit effectively, it is possible to prevent the corrosion and peeling in the thick film circuit generates very effectively.
[0046]
As described above, according to the present invention, when the plated metal layer is applied to the metallized wiring conductor on the upper surface of the ceramic wiring substrate in the ceramic mother substrate, the ceramic that does not cause corrosion, peeling, or the like in the thick film circuit on the lower surface A method for manufacturing a wiring board could be provided.
[Brief description of the drawings]
FIG. 1A is a cross-sectional view and FIG. 1B is a plan view showing an example of an embodiment of a method for producing a ceramic wiring board according to the present invention.

Claims (1)

Forming the vertical and horizontal dividing grooves at least on the lower surface of the ceramic matrix substrate, forming a main Taraizu wiring conductor on the upper surface of the ceramic matrix wherein the dividing groove rectangular regions partitioned by the substrate,
Forming a thick film circuit on the lower surface of the rectangular region of the ceramic mother substrate ;
A step of depositing a protective glass layer on the thick film circuit,
Coating the dividing grooves with a coating material made of low-melting glass;
A step of coating the thick film circuit covered with the protective glass layer with a coating layer made of an organic resin, a step of applying a masking tape so as to cover almost the entire lower surface of the ceramic mother substrate,
Applying a plated metal layer to the metallized wiring conductor of the ceramic mother board to which the masking tape is applied;
Method for producing a ceramic wiring board characterized that you include a.

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