JP3740374B2 - Multiple wiring board - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a multi-piece wiring board in which a large number of areas serving as wiring boards on which electronic components such as semiconductor elements, capacitive elements, and resistance elements are mounted are arranged and each wiring board area is partitioned by dividing lines. In detail, the dividing conductor is formed by cutting the wiring conductor layer and the insulating coating layer formed between a large number of substantially rectangular wiring board regions arranged vertically and horizontally on a mother board made of a ceramic material, The present invention relates to a multi-cavity wiring board having excellent mechanical bonding strength of a wiring conductor layer to a mother board at a cut portion and excellent reliability.
[0002]
[Prior art]
A large number of wiring boards are provided on a mother board made of an insulating material such as an aluminum oxide sintered body, a mullite sintered body, an aluminum nitride sintered body, a silicon nitride sintered body, and a glass ceramic sintered body. Arranging approximately square wiring board areas vertically and horizontally, forming a wiring conductor layer made of a metal material such as copper, silver, palladium, tungsten, molybdenum, manganese on the surface and inside of each wiring board area, and adjacent to each other A dividing groove is formed between the wiring board regions, and a wiring conductor layer is provided between the adjacent wiring board regions as necessary. By dividing this multi-cavity wiring board along the dividing groove, a wiring board having a wiring conductor layer is obtained. On the wiring board, electronic components such as a semiconductor element, a capacitor element, and a resistance element are mounted, and each electron An electronic device is obtained by electrically connecting the electrode of the component to the wiring conductor layer.
[0003]
Such a multi-piece wiring board generally prepares a large area green sheet formed by forming a ceramic material powder into a sheet shape together with an organic solvent / binder, and between each area to be each wiring board and each area, Metal paste obtained by adding solvent, binder, etc. to powder of metal material such as copper, silver, palladium, tungsten, molybdenum, manganese, etc. is printed, and then groove processing is performed between each wiring board area with a mold etc. It is manufactured by forming divided grooves and firing at a high temperature.
[0004]
At the same time, in order to increase the mechanical bonding strength of the wiring conductor layer to the mother board, it is often used to continuously cover the surface of the mother board and the outer periphery of the wiring conductor layer with an insulating coating layer. By covering the mother board surface and the outer periphery of the wiring conductor layer with an insulating coat layer, the mechanical bonding strength of the wiring conductor layer to the mother board is improved, and the wiring conductor layer can be miniaturized. This is because by devising the shape of the insulating coat layer, it is possible to easily form an electrode for component mounting using the opening. Such an insulating coating layer is formed by printing a metal paste on a green sheet and then printing a ceramic paste obtained by adding an organic solvent or the like to a powder of a ceramic material such as aluminum oxide.
[0005]
[Problems to be solved by the invention]
In this way, the strength of mechanical bonding of the wiring conductor layer to the mother board is improved by the insulating coat layer.
[0006]
However, when manufacturing a multi-piece wiring board having such an insulating coat layer, when the divided grooves that partition the wiring board area are formed between adjacent wiring board areas in the process of forming the divided grooves before firing. The insulation coating layer and the wiring conductor layer formed between the wiring board regions are cut when the mold is pushed in, and the contact resistance between the insulation coating layer and the mold is large when the mold is pulled up, so that the mold is lifted up. It will be lifted with. At that time, the bonding strength between the insulating coat layer and the wiring conductor layer is higher than the bonding strength between the wiring conductor layer and the mother board, and in addition, the metal paste that becomes the wiring conductor is brittle because it contains a large amount of metal powder, There is a problem that separation occurs between the wiring conductor layer and the mother board, or voids are generated inside the wiring conductor layer due to deformation of the wiring conductor layer, resulting in an increase in electrical resistance, disconnection, etc., resulting in a decrease in electrical connection reliability. there were.
[0007]
In this case, simply reducing the contact area between the mold and the insulation coating layer, or simply reducing the coverage area of the wiring conductor layer with the insulation coating layer, the separation of the wiring conductor layer from the mother substrate by the formation of the dividing grooves and wiring It is possible to suppress the generation of voids inside the conductor layer, but the problem is that the thickness of the insulation coating layer that covers the wiring conductor layer decreases, and the mechanical bonding strength between the wiring conductor layer and the mother board decreases. There was a point.
[0008]
[Means for Solving the Problems]
As a result of various studies on the above problems, the present inventor has found that the thickness of the wiring conductor layer at the portion cut by the dividing groove is Tm (mm), the thickness of the insulating coating layer is Tc (mm), and the wiring conductor layer by the insulating coating layer. Between the range of Lo and Tc / Tm and the separation of the wiring conductor layer from the mother substrate and the generation of voids inside the wiring conductor layer when the covering width of the outer peripheral portion is Lo (mm) It was found that there is an interactive relationship, and it was found that it is possible to suppress the occurrence of peeling of the wiring conductor layer by determining the range of Lo and Tc / Tm, and thus the present invention was devised. It is a thing.
[0009]
That is, the multi-cavity wiring board of the present invention is formed by forming a plurality of substantially square wiring board regions arranged vertically and horizontally on a flat mother board made of a ceramic material, and between adjacent wiring board areas. And an insulating coat layer that continuously covers the surface of the wiring conductor layer and the mother board and the outer periphery of the wiring conductor layer, and the wiring conductor layer and the insulating coating layer are cut to form the wiring A multi-piece wiring board in which a dividing groove for partitioning a substrate region is formed, wherein the wiring conductor layer and the insulating coating layer have a thickness Tm (mm) of the wiring conductor layer at a portion cut by the dividing groove. ), When the thickness of the insulating coating layer is Tc (mm) and the coating width of the outer periphery of the wiring conductor layer by the insulating coating layer is Lo (mm), the following relationship:
0.4 ≦ Tc / Tm ≦ 2.0
And
0.1 ≦ Lo ≦ −0.4375 × (Tc / Tm) +1.275
It is characterized by satisfying.
[0010]
Further, the multi-piece wiring board of the present invention has the following relationship Lo ≦ −0.4375 × (Tc / Tm) +0.975 in the above configuration.
It is characterized by satisfying.
[0011]
According to the multi-cavity wiring board of the present invention, the insulating coating layer that continuously covers the wiring conductor layer and the surface of the mother board and the outer periphery of the wiring conductor layer is formed between adjacent wiring board regions. A thickness Tm of the wiring conductor layer in a portion cut by the dividing groove of the multi-piece wiring board in which the dividing groove for dividing the wiring board region is formed by cutting the wiring conductor layer and the insulating coating layer; By determining the relationship between the thickness Tc of the insulating coat layer and the covering width Lo of the outer peripheral portion of the wiring conductor layer by the insulating coating layer as described above, the mechanical bonding strength of the wiring conductor layer to the mother board is reduced. Since the contact resistance between the insulating coating layer and the mold can be lowered to the extent that the above-mentioned problems are not generated within the range where it does not occur, the mechanical bonding strength of the wiring conductor layer to the mother board is good, and Odor processing Occurrence of peeling of the wiring conductor layer when pulling the divided grooves formed can be suppressed, it is possible to obtain a high electrical connection reliability.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Next, the present invention will be described with reference to the accompanying drawings.
[0013]
FIG. 1A is a perspective view showing an example of an embodiment of a multi-cavity wiring board according to the present invention, wherein 1 is a mother board, 2 is a wiring conductor layer, and 3 is an insulating coating layer. Each wiring conductor layer 2 and insulating coat layer 3 are formed between the wiring board region 4 and the region 4 on the surface of the mother substrate 1. Dividing grooves 1 a are formed between the regions 4 to divide the mother board 1 into the individual wiring substrate regions 4, and the wiring conductor layer 2 and the insulating coat layer 3 are formed between the wiring substrate regions 4. The wiring conductor layer 2 and the insulating coating layer 3 are cut to form the division grooves 1a. By dividing the mother board 1 along the dividing grooves 1a, a wiring board 5 shown in a perspective view in FIG. 1B is obtained.
[0014]
The mother board 1 serves as an insulating base for mounting electronic components such as semiconductor elements, capacitive elements, and resistance elements on the divided wiring board 5, and includes a glass ceramic sintered body, an aluminum oxide sintered body, A flat substrate made of a ceramic material such as a mullite sintered body or an aluminum nitride sintered body. In the case of a glass ceramic sintered body, an organic solvent, binder, plasticizer, etc. are added to a powder of borosilicate glass / aluminum oxide to form a slurry, which is formed into a sheet by the doctor blade method or the like. A plurality of green sheets obtained as described above are laminated as necessary and fired at about 1000 ° C.
[0015]
The wiring conductor layer 2 electrically connects the electrodes of electronic components (not shown) mounted on the wiring board 5 to the wiring board 5 via a conductive connecting material such as solder or bonding wires. When the base material 1 is a ceramic material that can be fired at around 1000 ° C. such as a glass ceramic sintered body, it is made of a metal material such as copper, silver, palladium, etc., and 1500 ° C. such as an aluminum oxide sintered body. When the ceramic material fired as described above is used as the mother substrate 1, it is formed of a refractory metal material such as tungsten or molybdenum. For example, when the glass ceramic sintered body is used as the base substrate 1, the wiring conductor layer 2 is prepared by adding an organic solvent, a binder, etc. to a metal powder such as copper, silver, palladium, etc. Is formed on a green sheet to be the mother substrate 1 by printing it in a predetermined pattern by a screen printing method or the like.
[0016]
The wiring conductor layer 2 preferably has a cross-sectional shape in which the peripheral portion is thinner than the central portion when the metal paste is applied. By doing so, the step between the peripheral portion of the wiring conductor layer 2 and the mother substrate 1 can be reduced, and in the application of a ceramic paste or glass paste forming the insulating coating layer 3 described later, uneven coating and voids are generated. Can be suppressed.
[0017]
In general, the wiring conductor layer 2 is formed between the wiring board regions 4 to be the wiring board 5 for reasons of design such as circuit design or for facilitating conduction when a plating layer is deposited on the surface thereof. Therefore, it is necessary to form the wiring board regions 4 between the wiring board regions 4.
[0018]
The insulating coat layer 3 covers the peripheral portion of the wiring conductor layer 2 and the mother board 1 together to improve the mechanical bonding strength of the wiring conductor layer 2 to the mother board 1. As the material for forming such an insulating coat layer 3, an appropriate material is selected and used in accordance with the firing conditions of the ceramic material forming the mother substrate 1. For example, a glass ceramic sintered body that can be fired at around 1000 ° C. uses glass powder such as borosilicate glass as a main component, and an aluminum oxide sintered body that is fired at 1500 ° C. or higher, such as aluminum oxide. Ceramic powder is used as the main component. A glass paste or ceramic paste obtained by adding an organic solvent or a binder to these powders is printed on the mother substrate 1 from the surface of the green sheet serving as the mother substrate 1, and the surface of the metal paste serving as the wiring conductor layer 2 It is formed by printing and coating so as to continuously cover the outer periphery of the film.
[0019]
If the contact angle of the outer edge portion contacting the mother board 1 with respect to the mother board 1 is set to 60 degrees or less, the insulating coat layer 3 is caused by a temperature change when using the wiring board 5 after mounting electronic components. It is possible to alleviate the stress concentration of the thermal stress caused by the difference in thermal expansion coefficient between the electronic component and the electronic component, and to effectively prevent the insulating coat layer 3 from being peeled off from the mother substrate 1.
[0020]
The dividing groove 1a is used to divide each wiring board region 4 of the mother board 1 into individual wiring boards 5. For example, a gold in which cutting blades are arranged corresponding to the dividing grooves 1a to be formed. It is formed by pressing the mold against a green sheet to be the mother substrate 1.
[0021]
In the present invention, as shown in FIG. 2A, which is a detailed view of a portion A in FIG. 1, and in FIG. The thickness of the wiring conductor layer 2 at the part that is sometimes cut is Tm (mm), the thickness of the insulating coating layer 3 is Tc (mm), and the coating width of the outer peripheral portion of the wiring conductor layer 2 by the insulating coating layer 3 is Lo (mm). The following relationship
0.4 ≦ Tc / Tm ≦ 2.0
And
0.1 ≦ Lo ≦ −0.4375 × (Tc / Tm) +1.275
It is important to satisfy
[0022]
That is, in the diagram shown in FIG. 3 in which Tc / Tm is shown on the horizontal axis and Lo (unit: mm) is shown on the vertical axis, it is important to satisfy the range including the region 1 and the region 2.
[0023]
Here, when Tc / Tm> 2.0 or Lo> −0.4375 × (Tc / Tm) +1.275, the insulating coat layer 3 is made of gold with respect to the thickness and width of the wiring conductor layer 2 when the dividing groove 1a is formed. By increasing the cross-sectional area in contact with the mold, the contact resistance between the insulating coat layer 3 and the mold increases, and when the mold is lifted, the insulating coat layer is lifted upward. Due to the formation of cavities in the conductor layer 2, the electrical resistance of the wiring conductor layer 2 tends to increase, resulting in poor electrical characteristics. In addition, when Lo <0.1 or Tc / Tm <0.4, since the coating width or thickness of the insulating coating layer 3 sufficient to cover the peripheral portion of the wiring conductor layer 2 is not reached, the wiring conductor layer 2 and the mother board 1 tends to cause a decrease in the mechanical joint strength.
[0024]
In particular, when a glass ceramic sintered body is used as the mother substrate 1,
0.4 ≦ Tc / Tm ≦ 2.0
And
0.1 ≦ Lo ≦ −0.4375 × (Tc / Tm) +0.975
That is, it is important to satisfy the range of region 2 in FIG. This is because the insulating coating layer 3 is formed of a ceramic paste or glass paste mainly composed of glass such as borosilicate glass due to the limitation of the sintering temperature, and therefore the insulating coating layer 3 used for other high-temperature sintering materials is used. This is because the contact resistance with the mold is higher than the material.
[0025]
Further, the thickness Tm of the wiring conductor layer 2 is preferably formed in the range of 0.015 mm to 0.075 mm from the viewpoint of electrical resistance characteristics. Further, the thickness Tc of the insulating coat layer 3 satisfies 0.4 ≦ Tc / Tm in relation to the thickness Tm of the wiring conductor layer 2 from the viewpoint of reinforcing the mechanical joint strength between the wiring conductor layer 2 and the mother board 1. is important.
[0026]
Further, the wiring conductor layer 2 has a plating layer (not shown) made of a metal or an alloy thereof having good corrosion resistance such as nickel, copper, gold, palladium, solder wettability and bonding wire bonding property on the exposed surface. 1 μm to 20 μm, for example, it is preferable to deposit a nickel plating layer with a thickness of 0.5 μm to 15 μm and a gold plating layer with a thickness of 0.5 μm to 5 μm.
[0027]
Insulating coat layer 3 generally has the same color as the ceramic material constituting base substrate 1 and is colorless and substantially transparent when glass powder is the main component, but insulating coat layer 3 is reliably formed. In order to check whether or not the metal substrate has been used, a coloring agent such as a metal oxide such as chromium oxide is added in the range of 3 wt% to 7 wt%, so that the mother board 1 and the wiring conductor Visibility can also be improved by a clear color difference from the layer 2.
[0028]
Further, when the insulating coating layer 3 is viewed from above, the corner coating portions are rounded in a radius of curvature range of 0.040 mm to 0.120 mm, so that the insulating coating layer 3 is further layered on the mother substrate 1. It can be reliably and firmly attached, and the mechanical bonding strength of the wiring conductor layer 2 to the mother substrate 1 can be further improved.
[0029]
Note that the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. For example, as shown in a detailed view similar to FIG. 2A in FIG. 4, a through-hole 6 penetrating the mother board 1 or a part of the wiring conductor layer 2 defined by the dividing groove 1a is not present. It is possible to adapt even when a through hole (not shown) exists.
[0030]
【The invention's effect】
According to the multi-cavity wiring board of the present invention, the thickness of the wiring conductor layer, the thickness of the insulating coating layer, and the wiring conductor layer by the insulating coating layer at the portion cut by the dividing groove of the wiring conductor layer and the insulating coating layer. By defining the range of the coating width of the outer peripheral portion of the wire, it is possible to suppress the occurrence of peeling inside the wiring conductor layer at the time of dividing groove formation, and to ensure the mechanical bonding strength of the wiring conductor layer to the mother board, This makes it possible to obtain high electrical and mechanical joint reliability.
[Brief description of the drawings]
FIG. 1A is a perspective view showing an example of an embodiment of a multi-cavity wiring board according to the present invention, and FIG. 1B is a perspective view showing an example of a wiring board obtained by dividing a mother board. is there.
2A is a detailed view of a portion A in FIG. 1A, and FIG. 2B is a cross-sectional view of a main part in a BB ′ cross section in FIG.
FIG. 3 is a diagram showing a region where the ratio of the thickness Tc of the insulating coat layer and the thickness Tm of the wiring conductor layer and the covering width Lo of the outer periphery of the wiring conductor layer by the insulating coating layer should be satisfied in the present invention. is there.
4 is a detailed view similar to FIG. 2 (a) showing another example of the embodiment of the multi-cavity wiring board of the present invention. FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Mother board | substrate 1a ... Dividing groove 2 ... Wiring conductor layer 3 ... Insulation coat layer 4 ... Wiring board area | region 5 ... Wiring board 6 ... Through-hole

Claims (2)

A plurality of substantially rectangular wiring board regions arranged vertically and horizontally are formed on a flat mother board made of a ceramic material. Between adjacent wiring board areas, a wiring conductor layer and a surface of the mother board are formed. An insulating coat layer that continuously covers the outer peripheral portion of the wiring conductor layer is formed, and a plurality of dividing grooves that divide the wiring board region by cutting the wiring conductor layer and the insulating coating layer are formed. The wiring conductor layer and the insulating coating layer are individual wiring boards, and the wiring conductor layer and the insulating coating layer have a thickness Tm (mm) and a thickness of the insulating coating layer Tc (mm) at the portion cut by the dividing groove. A multi-cavity wiring board characterized by satisfying the following relationship when the coating width of the outer peripheral portion of the wiring conductor layer by the insulating coating layer is Lo (mm).
0.4 ≦ Tc / Tm ≦ 2.0
And
0.1 ≦ Lo ≦ −0.4375 × (Tc / Tm) +1.275 The thickness Tm of the wiring conductor layer, the thickness Tc of the insulating coating layer, and the covering width Lo (mm) of the wiring conductor layer by the insulating coating layer satisfy the following relationship. Multi-piece wiring board.
Lo ≦ −0.4375 × (Tc / Tm) +0.975

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