JPH11135915A - Manufacture of ceramic circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the removal treatment time of an unnecessary brazing material, by etching a metallic plate which is joined to a ceramic board using a brazing material, and then using water solution wherein iodine and iodine compound are added. SOLUTION: Silver brazing paste is applied all over a ceramic substrate 10. A copper plate 14 is put on it and is heated to 790 to 1063 deg.C, and the copper plate 14 and the ceramic substrate 10 are brazed. Silver brazing paste fuses to constitute a silver brazing layer 16. The copper plate 14 is provided with an etching resist layer 18 and is etched by liquid of cupric chloride and hydrochloric acid for forming a specified circuit. An unnecessary silver brazing layer 16' is removed by using etchant containing iodine and iodine compound at least 5 wt.% in the total. A peeling time (15 minutes) can be greatly reduced by using solution of iodine (5%) and iodine compound (potassium iodide 30%) for etching an unnecessary brazing material layer in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic circuit board by an active metal brazing method, and more particularly to a method for manufacturing a circuit board in which a metal plate is joined on a ceramic substrate using a brazing material.

[0002]

2. Description of the Related Art A method for manufacturing a ceramic circuit board, for example, by an active silver brazing method using silver brazing as a metal brazing.
In the method of manufacturing the DBC substrate (Direct Bonding Copper Substrate), active silver solder is applied to a ceramic substrate, a copper plate is placed on the substrate, brazing is performed, a resist layer is printed, and then the copper plate is etched. To form a predetermined circuit, and finally, unnecessary silver solder is removed again from the circuit board by etching.

Conventionally, an etching solution containing a fluoride solution such as ammonium hydrogen fluoride or a fluoride + hydrogen peroxide solution as a main component has been used for removing the unnecessary brazing material by etching. However, since such an etching solution has a low etching speed, it takes 30 minutes or more to remove a brazing material having a thickness of about 30 μm.
In addition, when hydrogen peroxide is used, the composition of the etchant may change over time due to spontaneous decomposition of the same component, so strict analysis and management of the solution composition is necessary for long-term use of the etchant. And it took time to manage the liquid.

[0004]

Therefore, the production of a DBC substrate by the conventional active silver brazing method has a problem in terms of cost and tends to show variations in performance.

Here, the present invention provides a method capable of etching a brazing material in a shorter time using a more stable etching solution as compared with a conventional etching solution. It is intended to solve the problems of the prior art.

[0006]

Means for Solving the Problems In order to solve the above-mentioned problems, the present inventors evaluated the etching solutions of various components in order to increase the etching speed of the brazing material and stabilize the etching solutions. It has been found that the above-mentioned object can be achieved by using a solution containing iodine and an iodine compound as main components, and the present invention has been completed.

According to the present invention, after joining a metal plate to a ceramic substrate via a brazing material, the metal plate is etched into a predetermined shape, and then unnecessary brazing material is removed with an aqueous solution containing iodine and an iodine compound. A method for manufacturing a ceramic circuit board, comprising:

[0008]

Next, the present invention will be described more specifically with reference to the accompanying drawings. In the following, the present invention will be described by taking a method of manufacturing a DBC substrate by an active silver soldering method as an example.

FIGS. 1 (a) to 1 (d) show each step of the method for manufacturing a ceramic circuit board according to the present invention.
In (a), a silver brazing paste 12 is applied on the entire surface of a ceramic substrate 10 by appropriate means. Next, the copper plate 14 is placed thereon and heated to, for example, 790 to 1063 ° C., and the copper plate and the ceramic substrate are brazed. At this time, the silver brazing paste 12 is melted to form the silver brazing layer 16. FIG.
See (b).

The copper plate 14 is a material constituting a circuit.
As shown in (c), a predetermined circuit is formed by providing an etching resist layer 18 and then performing etching using an etching solution of cupric chloride + hydrochloric acid.

Here, the above-mentioned silver brazing layer 16 cannot be removed simultaneously with the etching removal of the copper plate. Therefore, in the related art, after a circuit of a copper plate is once formed, etching with, for example, a fluoride + hydrogen peroxide solution is performed while the circuit portion is masked.

However, in the case of the present invention, FIG.
As shown in (d), for example, an unnecessary silver brazing layer 16 ′ is formed by using an etching solution containing iodine and an iodine compound in a total of 5% by weight or more, preferably in a total of 30% by weight or more.
I.e. the silver braze layer 1 in the unmasked areas
Remove 6 '.

The iodine compound that can be used in the present invention is not particularly limited, and examples thereof include an iodide of an alkali metal.

The composition of the etching solution used in the present invention is not particularly limited, but preferably contains iodine and an iodine compound in a total amount of 5% by weight or more, preferably 30% by weight or more. Iodine is contained, for example, at about 2 to 10%. It is sufficient that the upper limit of iodine is 20%.

[0015] Table 1 below compares the etching rates of brazing materials with various etchants. However,
Brazing material composition Ag: Cu: Zr = 72: 26: 2, brazing layer thickness:
30 μm, immersion temperature: 30 ° C.

[0016]

[Table 1] From the results shown in Table 1, it can be seen that the use of the iodine + potassium iodide solution for etching the unnecessary brazing material layer according to the present invention can greatly reduce the stripping time.

As will be understood by those skilled in the art from the above description, iodine and iodine compounds (eg, potassium iodide) do not spontaneously decompose unlike hydrogen peroxide, so that an etching solution Is stable over a long period of time and its management is easy.

[0018]

EXAMPLE In this example, an AlN substrate was prepared in advance by a conventional method, and then a ceramic circuit substrate was manufactured according to the steps shown in FIGS. 1 (a) to 1 (d). First, FIGS. 1 (a) and (b)
In the step (b), the copper plate is brazed, the copper plate etched in the step shown in FIG. 1 (c) is masked, and the unnecessary unnecessary silver brazing layer 16 'is removed by etching.
The speed at that time was evaluated for various etching solutions. Table 2 shows the results.

[0019]

[Table 2]

[0020]

As described above, according to the present invention,
By etching the brazing material with a liquid containing iodine and an iodine compound as a main component, the processing time can be reduced as compared with the conventional etching using a fluoride + hydrogen peroxide solution.

[Brief description of the drawings]

1 (a) to 1 (d) are process diagrams of a method for manufacturing a DBC substrate by an active silver brazing method.

Claims (1)

[Claims] After joining a metal plate to a ceramic substrate via a brazing material, the metal plate is etched into a predetermined shape,
Next, an unnecessary brazing material is removed with an aqueous solution containing iodine and an iodine compound.