CN103208473B

CN103208473B - Adopt the power model of laser welding terminal

Info

Publication number: CN103208473B
Application number: CN201210542721.6A
Authority: CN
Inventors: 余传武; 庄伟东
Original assignee: NANJING YINMAO MICROELECTRONIC MANUFACTURING CO LTD
Current assignee: NANJING YINMAO MICROELECTRONIC MANUFACTURING CO LTD
Priority date: 2012-12-15
Filing date: 2012-12-15
Publication date: 2016-01-20
Anticipated expiration: 2032-12-15
Also published as: CN103208473A

Abstract

The invention provides the power model adopting laser welding terminal, it comprises and covers copper ceramic substrate, and the first bronze medal covering copper ceramic substrate is provided with semiconductor chip and terminal on the surface; Described terminal is connected to the first bronze medal surface covering copper ceramic substrate by laser welding.Adopt laser welding terminal in the present invention, avoid because terminal soldering point is tired and cause Module Fail, and the resistance to elevated temperatures of module can be improved.

Description

Adopt the power model of laser welding terminal

Technical field

The present invention relates to a kind of power model using laser welding terminal.

Background technology

Existing power model, its terminal passes through braze soldering on DBC substrate, braze mainly contains tin lead, the plumbous silver of tin, Xi Yin and SAC, their melting range at 179-221 DEG C, due to the difference of material thermal expansion coefficient, because the change of temperature can cause thermal stress in the process that module uses, braze can produce plastic deformation under thermal stress repeated action.Also there is mechanical stress between terminal and outside connecting plate in module in addition in the process installed and used.Soldering point meeting under the effect of stress is tired and then cause crackle and cause losing efficacy.Laser welding utilizes high-octane laser pulse to carry out the localized heating in tiny area to material, and the energy of laser emission, by the diffusion inside of heat transfer to material, forms specific molten bath by after material fusing.It is a kind of novel welding manner, and can realize spot welding, butt welding, stitch welding, seal weld etc., depth-to-width ratio is high, weld width is little, and heat affected area is little, it is little to be out of shape, and speed of welding is fast, smooth welded seam, attractive in appearance, postwelding is without the need to process or only need simple process, and weldquality is high, pore-free, can accurately control, focal spot is little, and positioning precision is high, easily realizes automation.Welding characteristic belongs to melting and contactless welding, and operation process does not need pressurization.At present, laser welding is widely used in following field.

1. manufacturing application.Laser assembly solder technology is at home and abroad widely used in car manufacturing, and according to statistics, in global ranges in 2000, tailored plate Laser Tailor-welded Production Line is more than 100, produces car component welding blanket 7,000 ten thousand per year, and continues to increase at a relatively high speed.

2. field of powder metallurgy.Along with the development of science and technology, to material particular/special requirement in many industrial technologies, the material that application smelts method manufacture can not be satisfied the demand.Laser welding enters powdered metallurgical material manufacture field with the advantage of its uniqueness, application for powdered metallurgical material opens new prospect, the method welding diamond of soldering conventional in connecting as adopted powdered metallurgical material, because bond strength is low, heat affected area is wide particularly can not adapt to high temperature and requirement of strength high and cause brazing filler metal melts to come off, adopt laser welding can improve weld strength and heat-resisting quantity.

3. auto industry.In the later stage eighties 20th century, multikilowatt laser is successfully applied to industrial production, and laser welding production line appears at auto manufacturing on a large scale now, becomes one of outstanding achievement of auto manufacturing.

4. electronics industry.Laser welding in the electronics industry, is particularly widely used in microelectronics industry.Because laser welding heat affected area is little and heating is concentrated rapidly, thermal stress is low, thus in the encapsulation of integrated circuit and semiconductor device, demonstrate unique superiority, as the welding of the elastic thin-wall corrugated plate in transducer or thermostat, because its thickness is at 0.05-0.1mm, traditional welding method is adopted to be difficult to solve, TIG welds easy burn-through, plasma poor stability, influencing factor is many and adopt laser welding effect fine, is widely used.

5. biomedical.The various biological tissue of laser welding, method for laser welding compares with traditional sewing method, has identical speed fast, foreign body reaction is not had in agglutination, keep the engineering properties of welding position, be repaired tissue by advantages such as its protozoa Mechanical Characters of Composite Ground growths, thus obtain applying very widely.

6. other field.In other industry, laser welding also increases gradually, particularly in special material welding, as the laser welding to lithium ion battery, and the laser welding of plate glass.

Laser is at welding highly reflective and high thermal conductivity material such as aluminium, and when copper and alloy thereof, weldability can Stimulated Light change.Aluminium is the good conductor of heat and electricity, highdensity free electron makes it become the good reflection body of light, initial sheet reflectivity is more than 90%, this power density required when just exigent input power starts to ensure to weld, and once aperture generates, it improves rapidly the absorptivity of light beam, even can reach 90%, thus welding process is carried out smoothly.The material behavior of copper makes it very be suitable as conductor, is material first-selected in electronics industry.Material reflectance is also hinder the main cause of its good welds.When optical maser wavelength becomes 532nm from 1064nm, the reflectivity of copper and other materials just reduces greatly.Welding copper and copper alloy easily produces incomplete fusion and lack of penetration, therefore generally adopts concentration of energy, powerful thermal source coordinate the ancillary methods such as preheating.

Previously described braze welding, be by braze fusing being coupled together by workpiece, and when laser welding metal such as copper, be the fusion weld parent metal fusings such as copper being formed copper-copper, both have significant difference.

Summary of the invention

The object of this invention is to provide a kind of power model without soldering terminal, by laser welding terminal, avoid because terminal soldering point is tired and cause Module Fail, and the resistance to elevated temperatures of module can be improved.

The technical scheme realizing the object of the invention is: the power model adopting laser welding terminal, and it comprises and covers copper ceramic substrate (DBC), and the first bronze medal covering copper ceramic substrate (DBC) is provided with semiconductor chip and terminal on the surface; Described terminal is connected to the first bronze medal surface covering copper ceramic substrate by laser welding.

As a further improvement on the present invention, described terminal comprise top in order to be connected with external circuit and in order to the bottom covering the welding of copper ceramic substrate first bronze medal surface laser, the cross-sectional area of bottom be the 2-4 on top doubly.Top is generally square column or cylindrical.In order to the bottom pref. cylindrical covering copper ceramic substrate first bronze medal surface soldered.

As a further improvement on the present invention, described bottom is around its axis, have the groove that cross section is V-arrangement or U-shaped downwards, laser beam irradiation is to groove fusing groove and the metal covered on copper ceramic substrate (DBC) first bronze medal surface, metal crystallisation by cooling forms solder joint, forms terminal and the connection covering copper ceramic substrate (DBC) first bronze medal surface.

Accompanying drawing explanation

Fig. 1 is module 100 schematic diagram of embodiment 1.

Fig. 2 is the global shape figure of the terminal 3 of embodiment 1.

Fig. 3 A is the structural representation of the bottom 32 of embodiment 1.

Fig. 3 B is the profile that the bottom 32 of embodiment 1 arranges v-depression.

Fig. 3 C is the profile arranging U-shaped groove of the bottom 32 of embodiment 1.

Fig. 4 A is the profile that the terminal 3 of embodiment 1 arranges v-depression.

Fig. 4 B is the vertical view that the terminal 3 of embodiment 1 arranges v-depression.

Fig. 5 is that the laser beam of embodiment 1 is around terminal operating path schematic diagram.

Fig. 6 A is a kind of mode schematic diagram of laser beam around terminal work of embodiment 1.

Fig. 6 B is the another kind of mode schematic diagram of laser beam around terminal work of embodiment 1.

Fig. 7 is the solder joint schematic diagram of the laser welding terminal of embodiment 1.

Embodiment

Fig. 1 is power model 100 structural representation adopting laser welding terminal.It comprises covers copper ceramic substrate (DBC) 1, is welded on the chip 2 covered on copper ceramic substrate (DBC) first bronze medal surface with solder, and is covering the terminal 3 on copper ceramic substrate (DBC) first bronze medal surface by laser welding.The material of terminal 3 is copper, copper alloy or copper surface gold-plating, nickel, silver.Center distance between adjacent 3 terminals is greater than 5 millimeters, and the minimum spacing between terminals of adjacent 3 need ensure the minimum workplace distance of electric clearance and laser beam.

Fig. 2 shows the global shape figure of terminal 3.It comprises top 31 in order to be connected with external circuit and in order to the bottom 32 covering the welding of copper ceramic substrate first bronze medal surface laser.The cross-sectional area of bottom 32 is generally 2-4 times of top 31.Top 31 is generally square column or cylindrical.In order to bottom 32 pref. cylindrical covering copper ceramic substrate first bronze medal surface soldered.

Fig. 3 A, 3B and 3C show the structural representation of bottom 32 and the cutaway view of terminal of terminal 3.Terminal lower portion 32 has circle shape groove 321 around its axis A.V-shaped or the U-shaped of channel section.This two kinds of opening shapes are shown in Fig. 3 B and 3C respectively.

Specifically describe with v-depression in Fig. 4.V-depression represents with 321.Around axis A in the form of a ring, its external diameter R321 and internal diameter R322 is between cylinder 32 external diameter R320 and cylinder 31 external diameter R310 for groove 321.Cylinder 32 external diameter R320 is at 0.7-1.5 millimeter, and cylinder 31 external diameter R310 is at 0.4-0.7 millimeter.Groove 321 width is at 0.1-0.5 millimeter, and depth of groove D1 is at 0.1-0.8 millimeter, and the distance D2 of groove 321 lowest part distance terminal bottom surface is at 0.1-0.5 millimeter.

Fig. 5 is working laser beam path profile.Laser beam along the v-depression 321 of terminal lower portion 32 center line and move in a circle around terminal axis A, the operating path 4 of laser beam represents with arrow indication dotted line in figure.

Two kinds of typical way of working laser beam have been shown in Fig. 6 A and Fig. 6 B.Radiation modality is that laser beam continuous print to move in a circle an irradiation weld along the center line of v-depression 321 around terminal axis A, and operating path forms continuous print solid line circle, see the schematic diagram of Fig. 6 A; Another kind of mode is discrete, and laser beam is to move in a circle around terminal axis A along the center line of v-depression 321 every certain time interval and distance, and its operating path represents with the broken circle of a determining deviation, sees the schematic diagram of Fig. 6 B.

Fig. 7 is the solder joint schematic diagram of laser welding terminal.Laser beam irradiation termination recess 321 place and the metallic copper covered on copper ceramic substrate (DBC) 1 first bronze medal surface or copper alloy, laser beam irradiation is when weld welds, termination recess place and the metal covered on copper ceramic substrate (DBC) 1 first bronze medal surface all must reach molten condition, belong to the fusion weld of copper-copper.In this and common soldering, just braze melts and parent metal is non-fusible basic difference.Form solder joint 5 after metal crystallisation by cooling terminal is connected with DBC first bronze medal surface.In figure, black shaded area represents termination recess place and covers the solder joint schematic diagram of copper ceramic substrate (DBC) first bronze medal on the surface after metal molten crystallization.

Diagram herein also describes specific embodiment of the present invention; but the interest field of application claims protection is not limited to this; make use of basic conception of the present invention, the various distortion that person of ordinary skill in the field carries out and improvement, still belong to the interest field of request of the present invention.

Claims

1. adopt the power model of laser welding terminal, comprise and cover copper ceramic substrate (DBC), the first bronze medal covering copper ceramic substrate (DBC) is provided with semiconductor chip and terminal on the surface; It is characterized in that, described terminal is connected to the first bronze medal surface covering copper ceramic substrate by laser welding; Described terminal global shape is cylindricality, is smooth planar shaped bottom terminal; Described terminal comprise top in order to be connected with external circuit and in order to the bottom covering the welding of copper ceramic substrate first bronze medal surface laser, the cross-sectional area of bottom be the 2-4 on top doubly; Described top is square column or cylindrical ,described bottom is cylindrical; Described bottom, around its axis, has the groove that cross section is V-arrangement or U-shaped downwards.

2. power model according to claim 1, is characterized in that, described bottom welding face area is between 0.5-2 square millimeter, and bottom thickness is between 0.2-2 millimeter.

3. power model according to claim 1, is characterized in that, the center distance between terminals of adjacent is greater than 5 millimeters.

4. power model according to claim 1, is characterized in that, the material of described terminal is copper, copper alloy or copper surface gold-plating or nickel plating or silver-plated.

5. power model according to claim 1, is characterized in that, described recess width is at 0.1-0.5 millimeter, and the degree of depth is at 0.1-0.8 millimeter, and the distance of groove lowest part distance terminal bottom surface is at 0.1-0.5 millimeter.