JPH0736467B2 - Ceramic circuit board manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention joins a metal plate used for a power semiconductor module or the like to a ceramic substrate,
The present invention relates to a method of manufacturing a ceramics circuit board formed with a semiconductor circuit.

[0002]

2. Description of the Related Art Conventionally, there are various methods for joining a metal and a ceramic. Particularly, from the viewpoint of manufacturing a circuit board, the Mo-Mn method, the active metal brazing method, the copper sulfide method, the DBC method is used. Method and copper metallizing method. Among these, in the manufacture of high-power module boards, it is currently the mainstream to use copper as the metal and the active metal brazing method or the DBC method as the joining method with ceramics.
Furthermore, the use of aluminum nitride having high thermal conductivity as an insulating substrate is becoming widespread.

As a method of joining the copper plate and the aluminum nitride substrate, as an active metal brazing method, a brazing material containing an active metal is interposed between the copper plate and the aluminum nitride substrate, and heat treatment is performed to form a joined body. (For example, JP-A-60
-177634), or a DBC method in which a copper plate and an aluminum nitride substrate whose surface is oxidized are heat-bonded at a temperature equal to or lower than the melting point of copper and equal to or higher than the eutectic temperature of Cu ₂ O-O (for example, a special method). Kaisho 56-163093) is known. The active metal brazing method has the following advantages over the DBC method. (1) Since the bonding temperature is low, the residual stress caused by the difference in thermal expansion of AlN-Cu is small. (2) Since the bonding layer is a ductile metal, it has high durability against heat shock and heat cycles.

[0004]

However, in this active metal brazing method, the brazing material flows out between insulations when joined by heat treatment, that is, in a portion other than the copper plate circuit where electrical insulation is required, and the copper plate When a part is plated, there is a drawback that it is plated on this part to form the pattern outside plating. In order to solve this drawback, the present applicant previously proposed in a method of forming a copper plate circuit portion on an aluminum nitride substrate,
Do not apply the brazing material to the part where the copper plate is not joined, apply the brazing material to all other parts, and join the copper plate by heat treatment to form a joined body with cupric chloride, ferric chloride, etc. The copper plate circuit is formed by etching, and the unnecessary brazing material existing between the insulation is treated with a chemical solution such as HF alone or a mixed acid of HF and at least one inorganic acid selected from HNO ₃ , H ₂ SO ₄ and HCl. Proposed a treatment method (International Application No. PCT / JP90 / 01502). However, in this method, the effect of removing the unnecessary brazing material between the insulations is not sufficient, so that the yield decreases when the copper plate portion is plated. Moreover, since it takes a long time to completely remove the brazing material, even the brazing material joining the copper plates may be eroded, and the joining strength, heat shock resistance, and heat cycle resistance may decrease. .

The object of the present invention is to improve the yield of the pattern by improving the plating outside the pattern due to insufficient removal of the unnecessary brazing material between the insulations, and to reduce the decrease in the bonding strength due to the brazing material removal treatment and to reduce the heat shock resistance. To provide a method of manufacturing a ceramic circuit board having excellent heat resistance and heat cycle resistance.

[0006]

That is, according to the present invention, a brazing filler metal paste is applied on a ceramic substrate, a metal plate is bonded onto the ceramic substrate, and then the metal is etched. After removing the unnecessary brazing material by treating with an aqueous solution containing ammonium halide and then with an aqueous solution containing inorganic acid and hydrogen peroxide, or after etching the metal as described above, hydrogen halide and / or ammonium halide A method for manufacturing a ceramics circuit board is characterized in that an unnecessary brazing material is removed by treating with an aqueous solution containing an inorganic acid and hydrogen peroxide.

The present invention will be described in more detail below.

Usually, when the ceramic and the metal plate are joined by the active metal brazing method, the active metal reacts with the ceramic substrate to form a reaction product at the interface, and the metal components of the metal plate and the brazing material are mutually heated during heating. Diffuse into and bond firmly. In order to remove this reaction product, hydrogen halide and / or ammonium halide is used in the present invention, and fluorine is particularly preferable as the halogen. Among them, NH ₄ F is the most suitable from the viewpoint of safety, so that will be further described below as an example.

As the treatment conditions with the solution containing NH ₄ F, the temperature can be room temperature (18 ° C.) to 95 ° C. to remove the unnecessary brazing filler metal, preferably 40 to 95 ° C., especially 60 to 90 ° C. 95 ° C. Under this condition, even if the amount of the reaction product of the active metal and the ceramic substrate increased, the unnecessary brazing material can be easily removed. NH ₄ F concentration
0.1-40% by weight is preferred, especially 1-20% by weight and even 1
~ 10 wt% is optimal. If the NH ₄ F concentration is less than 0.1% by weight, the effect of removing the unnecessary brazing material is small, while if it is more than 40% by weight, it penetrates into the brazing material in the metal circuit part, and the required bonding strength can be maintained. Disappear. In addition, since the area where the ceramics substrate and the metal circuit are joined is reduced, the heat shock resistance and heat cycle resistance are also lowered, and the metal circuit portion is peeled off.

The most important feature of the present invention is that the alloy component consisting of the metal components of the metal plate and the brazing material is treated with an aqueous solution containing hydrogen halide and / or ammonium halide, or at the same time as the treatment. It is to be removed using a solution containing an inorganic acid such as ₂ SO ₄ , HNO ₃ , and HCl and H ₂ O ₂ , and H ₂ SO ₄ is the most desirable among the inorganic acids. This is because the dissociation constant of HF is about Ka = 10 ^-4, so the solution containing HF, NH ₄ F, etc. has a small metal-dissolving power, so that the brazing filler metal component cannot be completely removed by itself. But with inorganic acids such as H ₂ SO ₄
The metal component can be uniformly removed in a short time by oxidizing and dissolving the metal component with a solution containing H ₂ O ₂ .

The concentration of the inorganic acid such as H ₂ SO ₄ is preferably 5 to 40% by weight, and most preferably 7 to 30% by weight and further 10 to 23% by weight. If it is less than 5% by weight, the dissolving power of the alloy component becomes small, so that a sufficient removal effect cannot be obtained. On the other hand, if it is more than 40% by weight, the dissolving power of the alloy component becomes too large and the metal circuit part is also dissolved. Will end up.

The concentration of H ₂ O ₂ is preferably 1 to 30% by weight, particularly 5 to 25% by weight, more preferably 7 to 15% by weight. If it is less than 1% by weight, the dissolving power of the alloy components will be small, so a sufficient removal effect cannot be obtained, and if it is more than 30% by weight, H ₂ O ₂
It is difficult to control the composition of the liquid because of the severe decomposition of the liquid, and it becomes difficult to treat it under a certain condition.

In the present invention, the above treatment with hydrogen halide such as NH ₄ F and / or ammonium halide and the treatment with a solution containing an inorganic acid such as H ₂ SO ₄ and H ₂ O ₂ are separately performed. However, the same effect can be obtained by simultaneously performing two treatments with a solution containing these components.

The active metal in the present invention is not particularly limited as long as it reacts with the ceramic substrate to ensure the wettability of the brazing material, but considering the ease of use and the reaction with the ceramic substrate. , Titanium, zirconium, hafnium and alloys containing them as a main component, or compounds that decompose to produce them by the melting point of the brazing filler metal are preferable, and titanium, titanium-zirconium alloy, zirconium and hydrogen compounds thereof are most preferable. is there.

The metal composition of the brazing filler metal used in the present invention is not particularly limited, but examples of components excluding the active metal include Ni, Cu, Ag-Cu, Ag-Ni and the like. Considering the low melting temperature of the brazing material and the ease of use,
Those containing Ag-Cu as a main component are preferable.

Further, regarding the metal plate in the present invention,
Although the composition thereof is not particularly limited, copper, nickel, aluminum and alloys containing these as main components are generally used. Considering application to a power semiconductor module substrate, it is desirable to use a copper plate as the metal plate.

Further, examples of the ceramic substrate include silicon nitride, aluminum nitride, boron nitride, aluminum oxide, and those containing a composite system of these as a main component, but aluminum oxide and aluminum nitride are the most common. . Especially when considering application to a power semiconductor module substrate, aluminum nitride having high thermal conductivity is most preferable.

The joining in the present invention is a usual active metal brazing method and is performed under vacuum or in an inert atmosphere. An atmosphere that easily reacts with the active metal is not preferable, and an atmosphere capable of sufficiently maintaining the activity is required especially at a high temperature.

The "unnecessary brazing material" in the present invention means an active metal brazing material existing between circuits, on an edge surface and a side surface, and by remaining, it hinders the insulation resistance between the circuits and between the front and back surfaces of the substrate. Is.

[0020]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples.

Examples 1 to 12 and Comparative Examples 1 to 2 72 parts by weight of silver powder, 28 parts of copper powder, 5 parts of metal zirconium powder, 15 parts of terpineol and a toluene solution of polyisobutyl methacrylate as an organic binder were solidified in a weight ratio. Then, 1.5 parts of the mixture was added and kneaded well to prepare a brazing paste. This brazing paste was screen-printed on both sides of a 70 × 40 × 0.65 mm aluminum nitride substrate.

Next, after drying this substrate at 150 ° C. for 5 minutes,
A 70 × 40 × 0.25 mm copper plate was placed in contact with both sides and placed in a furnace. This sample was first heat-treated at 400 ° C in a high-purity nitrogen gas stream to sufficiently remove organic components, then heated to 880 ° C at 10 ° C / min, and heat-bonded at 880 ° C for 20 minutes at 1 × 10 ^-6 torr. Then, it was further cooled to room temperature at a temperature decrease rate of 2 ° C./min to obtain a joined body.

An ultraviolet-curable etching resist was applied on the circuit pattern on the copper plate of the joined body by a screen printing machine, and then an etching treatment was performed using a cupric chloride solution.

Next, as a first treatment for removing the unnecessary brazing material, the above-mentioned etching-treated product is treated with a 1-10 wt% solution of HF or NH ₄ F at 70 ° C. for 15 minutes, and as a second treatment, H 2 ₂ S
One of O ₄ , HNO ₃ and HCl is 8 to 30 wt% and H ₂ O
_It was treated with a mixed solution of 24 to 15% by weight at 50 ° C. for 5 minutes.

For each sample, after checking the brazing material removal state,
The bond strength was measured according to the following. Further, the samples produced in the same manner were tested for heat cycle resistance (in air) and heat shock resistance (in liquid), and the peeled state of the electrodes was observed. The results are shown in Table 1.

(1) Evaluation of brazing material removal state Method: Visual reference: ◯: Completely removed Δ: Partially retained ×: Entirely retained

(2) Peel strength (joint strength) Measuring equipment: Push Bull Gauge IMADA DPS II 20R Measuring conditions: Tensile speed; 50 mm / min

(3) Heat cycle resistance measuring instrument: rotary thermal shock tester Yashima Seisakusho TS
ER-2252-A Measurement condition: (in air) -40 ℃ × 30 minutes → 25 ℃ × 10 minutes → 125 ℃
× 30 minutes → 25 ° C × 10 minutes 500 cycles Standard: A: No electrode peeling B: Partial electrode peeling C: Complete electrode peeling

(4) Heat shock resistance Measuring instrument: thermal shock tester Yashima Seisakusho TSEL-2200-2 Measuring condition: (in liquid) 0 ° C × 10 minutes → 100 ° C × 10 minutes 300 cycles Standard: A: electrode peeling None B: Partial electrode peeling C: Complete electrode peeling

[0030]

[Table 1]

Examples 13 to 24 Samples obtained by etching with cupric chloride in the same manner as in Example 1 were treated with a solution having the composition shown in Table 2 at 50 ° C.
For 15 minutes, the same evaluation as in Example 1 was performed. The results are shown in Table 2.

[0032]

[Table 2]

[0033]

EFFECTS OF THE INVENTION According to the present invention, unnecessary brazing filler metal components can be easily removed without lowering the bonding state between the metal plate and the ceramics substrate and also lowering the heat shock resistance and heat cycle resistance. Since it can be removed and plating outside the pattern can be eliminated, the yield can be improved.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroto Horiuchi 1 Shinkai-cho, Omuta City, Fukuoka Prefecture Inspector, Omuta Factory, an electrochemical industry company Yukio Numasawa (56) Reference JP-A-3-18087 (JP, A) ) JP-A-63-47382 (JP, A) JP-A-2-209789 (JP, A)

Claims (2)

[Claims] 1. A brazing material paste is applied onto a ceramic substrate, a metal plate is bonded onto the ceramic substrate, the metal is etched, and then an aqueous solution containing hydrogen halide and / or ammonium halide is prepared, followed by an inorganic acid. And a method of manufacturing a ceramics circuit board, which comprises removing unnecessary brazing filler metal by treating with an aqueous solution containing hydrogen peroxide. 2. A brazing material paste is applied on a ceramic substrate, a metal plate is bonded onto the ceramic substrate, the metal is etched, and then a hydrogen halide and / or ammonium halide, an inorganic acid and hydrogen peroxide are included. A method for manufacturing a ceramics circuit board, which comprises removing unnecessary brazing filler metal by treating with an aqueous solution.