Ceramic substrate copper cladding low-temperature connection method for power module

A technology for ceramic substrates and power modules, applied in welding media, welding equipment, welding/welding/cutting items, etc., can solve problems such as low yield, lower surface flatness requirements, narrow process window, etc., to improve service life, The effect of lowering the connection temperature and reducing the residual stress

Inactive Publication Date: 2017-01-11
HARBIN INST OF TECH AT WEIHAI
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

DBC technology has high requirements on the surface flatness of ceramic substrate and copper, and its process window is narrow, which ultimately leads to low yield
In view of the above deficiencies, in the patent CN104409425A, the active solder AgCuTi or AgCuZr is used to realize the bonding of the ceramic substrate and copper, and the use of active brazing to realize the bonding of the ceramic substrate and copper can reduce the surface flatness requirements of the sample , but the high-temperature brazing filler metal used often leads to large residual stress in the ceramic substrate, which leads to its fracture and affects the service life

Method used

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  • Ceramic substrate copper cladding low-temperature connection method for power module

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] (1) Grind the surface of AlN ceramics with 1000# and 1500# diamond sand discs in turn, and polish the surface of oxygen-free copper with 800#, 1000# and 2000# sandpaper in turn, and then put the polished samples into acetone Ultrasonic cleaning for 15 minutes;

[0020] (2) Put Ag powder, Cu powder, Sn powder, Ti powder, and organic binder into a ball mill tank for mechanical ball milling of active solder paste. The mass fraction of Ag is 10%, the mass fraction of Cu is 20%, the mass fraction of Sn is 65%, the mass fraction of Ti is 5%, the mass ratio of organic binder to metal powder is 1:6, and the mechanical ball milling time for 6 hours;

[0021] (3) Coat 50 μm of active solder paste on the surface of AlN ceramics, then attach 0.3 mm thick oxygen-free copper to AlN, with solder paste in the middle, and apply a pressure of 15 MPa above the oxygen-free copper. Put the assembled sample into the brazing furnace, evacuate to 5×10-3Pa, then heat to 750ºC at a rate of 15º...

Embodiment 2

[0023] (1) Use 1000# and 1500# diamond sand discs in sequence to Al 2 o 3 The ceramic surface is polished, and the oxygen-free copper surface is polished with 800#, 1000# and 2000# sandpaper in sequence, and then the polished sample is ultrasonically cleaned in acetone for 20 minutes;

[0024] (2) Put Ag powder, Cu powder, Sn powder, Ti powder, and organic binder into a ball mill tank for mechanical ball milling of active solder paste. The mass fraction of Ag is 5%, the mass fraction of Cu is 30%, the mass fraction of Sn is 61%, the mass fraction of Ti is 4%, the mass ratio of organic binder to metal powder is 1:4, and the mechanical ball milling time for 8 hours;

[0025] (3) Coat 100μm of active solder paste on the surface of Al2O3 ceramics, then attach 0.5mm thick oxygen-free copper to Al2O3, with solder paste in the middle, and apply 15MPa pressure above the oxygen-free copper. Put the assembled sample into the brazing furnace, evacuate to 2×10-3Pa, then heat to 720ºC a...

Embodiment 3

[0027] (1) Grind the surface of AlN ceramics with 1000# and 1500# diamond sand discs in turn, and polish the surface of oxygen-free copper with 800#, 1000# and 2000# sandpaper in turn, and then put the polished samples into acetone Ultrasonic cleaning for 20 minutes;

[0028] (2) Put Ag powder, Cu powder, Sn powder, Ti powder, and organic binder into a ball mill tank for mechanical ball milling of active solder paste. The mass fraction of Ag is 5%, the mass fraction of Cu is 30%, the mass fraction of Sn is 61%, the mass fraction of Ti is 4%, the mass ratio of organic binder to metal powder is 1:4, and the mechanical ball milling time for 8 hours;

[0029] (3) Coat 100 μm of active solder paste on the surface of AlN ceramics, then attach 0.3 mm thick oxygen-free copper to AlN, with solder paste in the middle, and apply a pressure of 15 MPa above the oxygen-free copper. Put the assembled sample into the brazing furnace, evacuate to 5×10-3Pa, then heat to 720ºC at a rate of 20º...

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Abstract

The invention discloses a ceramic substrate copper cladding low-temperature connection method for a power module. The method includes the following steps that firstly, a ceramic substrate and oxygen-free copper are subject to surface treatment, and then are subject to acetone washing; secondly, Ag powder, Cu powder, Sn powder and Ti powder or the Ag powder, the Cu powder, In powder and the Ti powder are mixed to form metal powder, an organic binder is added into the metal powder, and a mixture is placed into a ball milling tank for mechanical ball milling so as to prepare active brazing filler metal paste; and thirdly, samples are assembled from top to bottom according to the sequence of the oxygen-free copper/ active brazing filler metal /the ceramic substrate, and connection is achieved in a vacuum brazing furnace. According to the method, the manner that low-melting-point elements are added into the active brazing filler metal is adopted, the connection temperature of the oxygen-free copper and the ceramic substrate is reduced, residual stress in the substrate is reduced, and the service life is prolonged.

Description

technical field [0001] The invention belongs to the field of electronic packaging, and in particular relates to a low-temperature connection method for covering copper on a ceramic substrate for a power module. Background technique [0002] In the field of electronic packaging, direct copper clad technology (DBC) is generally used to connect ceramic substrates to oxygen-free copper. DBC technology is to place copper foil on Al 2 o 3 On the ceramic substrate, heat to 1065~1085ºC in an oxygen-containing atmosphere, so that the copper foil is directly covered on the Al 2 o 3 on a ceramic substrate. The principle is that, combined with the Cu-O binary phase diagram, it can be seen that under a certain oxygen content, when heated to 1063ºC, Cu and O form a eutectic liquid phase CuO, and the eutectic liquid phase and Al 2 o 3 Ceramic contacts and reacts CuO+Al 2 o 3 =CuAl 2 o 3 , form a good wetting to the ceramic substrate and realize the connection. For new AlN cerami...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B23K1/008B23K35/26B23K1/20C04B37/02
CPCB23K1/008B23K1/206B23K35/025B23K35/262B23K2103/52C04B37/026
Inventor 宋晓国付伟赵一璇李佳迅周志强刘多曹健
Owner HARBIN INST OF TECH AT WEIHAI
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