CN1376020A

CN1376020A - Making process of metallized ceramic base plate

Info

Publication number: CN1376020A
Application number: CN 01105682
Authority: CN
Inventors: 张成邦
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-03-15
Filing date: 2001-03-15
Publication date: 2002-10-23
Anticipated expiration: 2021-03-15
Also published as: CN1203737C

Abstract

This invention provides a method of manufacturing ceramics-metallized base plates containing roughing of ceramic base plate granulat, chemical coppering, electrical coppering, wet etching graph, co-crystallization and braze welding to get metallized graphs of high precision, and metallized layer with strong adhesive, force, good heat-resistance, strong anti-heat-impact and excellent surface braze-wedling, which has low cost and is convenient to product in a large scale.

Description

A kind of manufacture method of metallized ceramic base plate

The invention belongs to the manufacturing technology field of metallized ceramic base plate.

As everyone knows, the manufacture method of the metallized ceramic base plate that is widely used as electronic material has membrane process, thick film, wet method metallization and direct bit copper method etc.

Membrane process is to utilize vacuum evaporation, sputter etc. to form metallic film on ceramic base plate surface, forms metallization pattern through etching.This method advantage is the pattern precision height, is suitable for the High Density Packaging circuit.Shortcoming is that conductor resistance is big, in addition, and cost of equipment costliness, manufacturing cost height.

Thick film be will contain gold, silver, copper etc. the conductor paste silk screen printing on ceramic base plate surface, form metallization pattern through sintering.This method advantage is that operation is few, is fit to large-scale production, and shortcoming is that pattern precision is lower, is difficult to use in the assembled with high precision circuit, and in addition, the glass ingredient in the conductor paste often makes metallization pattern top layer brazing property reduce.

The wet method metallization is meant: adopt chemical plating and electroplate to form metal layer on the surface of ceramic substrate, form metallization pattern through etching.This method can obtain high-precision figure, is suitable for the assembled with high precision circuit, and the metal layer thickness of formation is from several microns to 100 microns, and it also is suitable for the power circuit of big electric current, and in addition, low cost of manufacture is fit to size of the organization production.The weak point of this method is: because metal layer is that physical action by metal rivet obtains to the adhesive force of ceramic base plate surface, its heat resistance is relatively poor; Because easily take place to jump plating when chemical plating, often make coating adhesion inhomogeneous again, reliability is a greater impact.

So-called directly bit copper method is: utilize copper～oxygen eutectic principle, directly Copper Foil and aluminium oxide ceramic substrate or aluminium nitride ceramics substrate are carried out the eutectic soldering in certain temperature and atmosphere, form the composite material of pottery and copper, by etching Copper Foil is corroded into metallization pattern again.Wetting action, diffusion and chemical action that this method simultaneously produces at close ceramic substrate because of the eutectic liquid that has utilized the reaction of copper and oxygen to generate, the cupric aluminate composite oxides have been generated, thereby make the peel strength of Copper Foil reach 5～10Kg/cm, and, under 850 ℃ high temperature, intensity does not reduce yet.The thickness range of Copper Foil is 0.2mm～0.6mm, is particularly suitable for the power circuit of big electric current.But the live width of the metallization pattern that forms with this method can not be less than 0.25mm, so it can't be applied to the High Density Packaging circuit.

The object of the present invention is to provide a kind of metallized ceramic base plate; it not only has high accuracy figure, excellent adhesive strength, the metal level that braze ability is good; and have good thermal endurance and a thermal shock resistance; in addition; also have low manufacturing cost and be convenient to size of the organization production, not only be suitable for the High Density Packaging circuit but also be suitable for the power circuit of big electric current.

For achieving the above object, the manufacture method of metallized ceramic base plate of the present invention is: with ceramic base plate surface after alligatoring etc. is handled, form copper metallization with chemical plating and plating, wet method is etched into figure again, then, implement the eutectic soldering, 1065 ℃～1083 ℃ of brazing temperature ranges, soldering atmosphere is the nitrogen that contains 5～50ppm oxygen.

Below, be example with the aluminium oxide ceramic substrate, by main technique flow chart of the present invention, be further described.

Fig. 1 main technique flow process

Fig. 2 metallized ceramic base plate

Fig. 3 eutectic brazing device schematic diagram

1 ceramic substrate, 2 rivet holes, 3 chemical plating copper films, 4 copper electroplating layers, 5 eutectic solder joints

A import objective table B body of heater C control instrument D outlet objective table E gas flowmeter

The F grate

I advances II preheating zoneofoxidation III brazing area IV cooling zone V outlet

At first aluminium oxide ceramic substrate 1 being carried out surface coarsening handles, its objective is and on ceramic base plate surface, form rivet hole 2, coarsening solution can be selected aqueous slkali, for example NaOH, potassium hydroxide etc., also can select acid solution, for example hydrofluoric acid, nitric acid etc., the scope of surface roughness Ra is: 3 μ m～10 μ m, Ra is less than 3 μ m, the rivet effect is not obvious, and Ra not only will reduce ceramic base plate surface fineness greater than 10 μ m, but also cause after the etching residual copper in the rivet hole easily, destroy the insulation between figure.

Ceramic substrate after the alligatoring carries out ultrasonic waves for cleaning, its role is to the particle a little less than the adhesive force after some alligatoring is removed clean.Then, available stannous chloride and hydrochloric acid solution are handled the ceramic base plate surface sensitization; With palladium bichloride and hydrochloric acid solution ceramic base plate surface is carried out activity again and handle, purpose is to allow the nuclei of crystallization that ceramic base plate surface has uniformly, quantity is enough.

With the above-mentioned aluminium oxide ceramic substrate electroless copper of handling well, the prescription of chemical copper plating solution and operating condition are pressed table 1 and are carried out, and obtain chemical plating copper film 3, and its thickness range is 0.3 μ m～1.0 μ m.

Table 1 chemical copper plating solution prescription and operating condition

Copper sulphate 10g/l

EDTA 30g/l

37% formaldehyde 3g/l

Interfacial agent is an amount of

PH (NaOH) 12.8

70 ℃ of temperature

Again chemical plating copper film 3 is carried out the electro-coppering thickening by the solution formula and the operating condition of table 2, the thickness range of its copper layer 4 is 5 μ m～100 μ m.

Table 2 copper electroplating solution prescription and operating condition

Copper sulphate 75g/l

Sulfuric acid 180g/l

Current density 2A/dm ²

With wet etching the copper layer 4 that forms is corroded the metallization pattern that obtains as shown in Figure 2, the ceramic substrate that will have this figure again carries out the eutectic soldering by following condition, brazing temperature range: 1065 ℃～1083 ℃, and best 1068 ℃～1077 ℃.If brazing temperature is lower than 1065 ℃, eutectic reaction does not take place in copper and oxygen, does not just have wetting, diffusion and the chemical reaction of eutectic liquid to the aluminium oxide ceramic substrate surface, does not just have the generation of composite oxides cupric aluminate yet.If brazing temperature is higher than 1083 ℃, surpassed the fusing point of copper, can make 4 fusing of copper layer.Eutectic soldering atmosphere is selected nitrogen, mixes micro amount of oxygen in nitrogen, and its concentration range is 5～50ppm.If oxygen concentration is lower than 5ppm, the cupric aluminate lazy weight of generation influences the adhesive strength of copper layer to ceramic base plate surface, if oxygen concentration greater than 50ppm, certainly will cause the over oxidation of copper layer, also can occur the local melting of copper layer sometimes.This shows that effective control of eutectic soldering condition is key of the present invention.

Eutectic brazing device of the present invention has import I, preheating zoneofoxidation II, brazing area III, cooling zone IV, five parts of outlet V, as shown in Figure 3.The oxygen concentration scope is 100ppm～500ppm in the wherein preheating zoneofoxidation nitrogen, and temperature range is 600 ℃～950 ℃; The oxygen concentration scope is 5ppm～50ppm in the brazing area nitrogen, and temperature range is 1000 ℃～1083 ℃; The cooling zone is divided into slow cooling district, natural cooling district and water cooling district three parts again, in the cooling zone in the nitrogen oxygen concentration be controlled at below the 10ppm, guarantee the good conductive ability of copper layer 4.

Embodiment 1

With aluminium oxide ceramic substrate 1 dipping 60% sodium hydroxide solution of 96% purity, the heat treatment under 450 ℃, 5 minutes conditions of dry back, washing, pickling again, ultrasonic waves for cleaning is 10 minutes then, and it is immersed SnCl ₂In the 12g/l+HCl 6ml/l aqueous solution 2 minutes, immerse PdCL again ₂0.3g/l+HCL in the 2ml/l aqueous solution 1 minute, after the washing respectively solution formula and the operating condition by table 1 and table 2 carry out electroless copper and electro-coppering, its thickness is respectively 0.5 μ m and 35 μ m, carry out the eutectic soldering after becoming metallization pattern with wet etching, brazing temperature is 1070 ℃, and the oxygen concentration in the nitrogen is 120ppm in the preheating zoneofoxidation of brazing device, and brazing area is 12ppm, the cooling zone is 5ppm, and be 10 minutes the heating time of brazing area.

The result of present embodiment is as follows: the copper layer is 2.5Kg/mm to the tensile strength on aluminium oxide ceramic substrate surface ², heating is after 10 minutes in 850 ℃ of nitrogen, and tensile strength is still greater than 2.0Kg/mm ², the braze ability 100% of copper laminar surface.

The method of testing of tensile strength is in the present embodiment: on 2 * 2 (mm) of ceramic base plate surface metallic pattern with the vertical soldering of SnPb39 solder on diameter be the tinned copper wire of 0.8mm, then with the speed stretched vertically of 50 ± 5mm/min.

The method of testing of braze ability is: the surface is immersed through the ceramic substrate with 10 * 10 (mm) metallic pattern that gives weldering and handle in 250 ℃ the SnPb39 tin pot, 5 seconds time, taken out the wetted area that solder is measured in the back.

Embodiment 2

Thermal conductivity be the normal pressure-sintered aluminium nitride ceramics substrate of 170W/m.k after poach cleans, immerse 1mol/dm ³The sodium hydrate aqueous solution of concentration 60 minutes cleans the back and carries out sensitization, activation, electroless copper, electro-coppering and eutectic soldering by the condition of embodiment 1.Test by the method for testing of embodiment 1 then, the result is: the copper layer is 2.0Kg/mm to the tensile strength of aluminium nitride ceramics substrate surface ², heating is after 10 minutes in 850 ℃ of nitrogen, and tensile strength is not less than 1.8Kg/mm ², the braze ability 100% of copper laminar surface.

Adopt the present invention that ceramic substrate is metallized; owing to utilized the physical action of rivet and the chemical action of eutectic reaction simultaneously; so the metal layer that forms not only can go out the high accuracy figure with wet etching; and; metal layer has excellent adhesive strength and outstanding braze ability, good thermal endurance and good thermal shock resistance; in addition, low cost of manufacture is convenient to size of the organization production.Both being suitable for highdensity assembling circuit, and being suitable for the power circuit of big electric current again, is a kind of metallized method of ceramic substrate that has using value.

Claims

1. the manufacture method of metallized ceramic base plate is characterized in that:

At first with ceramic substrate alligatoring, ultrasonic waves for cleaning, sensitization processing, activation processing and electroless copper, its copper film 3 thickness ranges are 0.3 μ m～1.0 μ m;

Secondly with above-mentioned chemical plating copper film 3 usefulness electro-copperings thickening, its copper layer 4 thickness ranges are 5 μ m～100 μ m;

The 3rd, above-mentioned copper layer 4 usefulness wet etching are become metallization pattern;

At last, above-mentioned metal level and the ceramic substrate that has figure carried out the eutectic soldering, brazing temperature range is 1065 ℃～1083 ℃, and soldering atmosphere is nitrogen, and the concentration range of oxygen is 5ppm～50ppm in the nitrogen, and the holding time is 7～10 minutes.

2. according to the eutectic soldering described in the claim 1, its brazing device is characterised in that:

Body of heater is made up of 5 parts: import, preheating zoneofoxidation, brazing area, cooling zone, outlet.The temperature range of wherein preheating zoneofoxidation is 600 ℃～950 ℃, and the oxygen concentration scope is 100ppm～500ppm in the nitrogen; The temperature range of brazing area is 1000 ℃～1083 ℃, and the oxygen concentration scope is 5ppm～50ppm in the nitrogen; The cooling zone is divided into 3 parts: slow cooling district, natural cooling district and water cooling district, the oxygen concentration scope is below the 10ppm in the nitrogen.