Integrated welding material and welding method

Abstract

The invention relates to the technical field of welding materials, in particular to an integrated welding material and a welding method.The integrated welding material comprises a metal wire and a filling solder matrix, the metal wire comprises one or more of Ag, Au, Pb, Pt, Cu, Ni, Co, Fe, Mn, Mg, Ti, Zr, W and In and alloys of Ag, Au, Pb, Pt, Cu, Ni, Co, Fe, Mn, Mg, Ti, Zr, W and In, the filling solder matrix comprises one or more of Sn-based solder, Pb-based solder, In-based solder, Bi-based solder, Zn-based solder, Au-based solder, Cd-based solder and Ga-based solder, the wettability and voidage of the filling solder can be kept after the integrated solder is welded, meanwhile, due to the fact that the melting point of the filling material is high, good supporting force can be provided during welding, and after welding, the filling material is not prone to falling off. The metal wire with the high melting point and the filling solder form an IMC layer, so that the welded material has better mechanical performance and safety and reliability, tin overflow is avoided during welding, and the phenomenon of poor welding is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of welding materials, and in particular to an integrated welding material and a welding method. Background Art

[0002] Solders are widely used in the electronics industry to achieve electrical and mechanical connections within components and between components and printed circuit boards. With the miniaturization of components and the development of surface mounting technology, the requirements for the microstructural stability, mechanical properties and creep resistance of solders are becoming increasingly higher.

[0003] In the field of soldering, one or more materials are joined to each other by applying solder to the contact surfaces of the materials to be joined. However, when soldering some heavier modules, solder may overflow and cause poor soldering. Summary of the invention

[0004] The purpose of the present invention is to provide an integrated welding material and a welding method, aiming to solve the problem that when existing solder materials are used to weld some heavier modules, tin overflow will cause poor welding.

[0005] To achieve the above objectives, in a first aspect, the present invention provides an integrated welding material, comprising a metal wire and a filler solder matrix, wherein the metal wire comprises one or more of Ag, Au, Pb, Pt, Cu, Ni, Co, Fe, Mn, Mg, Ti, Zr, W and In and their alloys, and the filler solder matrix comprises one or more of Sn-based solder, Pb-based solder, In-based solder, Bi-based solder, Zn-based solder, Au-based solder, Cd-based solder and Ga-based solder.

[0006] In a second aspect, the present invention further provides an integrated welding material welding method, which is applied to the integrated welding material described in the first aspect, and comprises the following steps:

[0007] Placing the chip and the integrated welding material in a formic acid furnace, and sequentially performing vacuuming, nitrogen flushing and vacuuming operations on the formic acid furnace;

[0008] The formic acid furnace is heated to 180° C., vacuumed, filled with formic acid, heated again to 220° C., and the chip is welded to the integrated welding material;

[0009] The formic acid furnace is heated to 250° C., and then the formic acid furnace is evacuated, nitrogen is introduced, and the formic acid furnace is cooled to room temperature to complete the welding of the integrated welding material.

[0010] The specific method of placing the chip and the integrated welding material in a formic acid furnace, and sequentially performing vacuuming, nitrogen flushing and vacuuming operations on the formic acid furnace is as follows:

[0011] The chip and the integrated welding material are placed in a formic acid furnace, and the formic acid furnace is evacuated to 1 mbar and maintained for 30 seconds;

[0012] The formic acid furnace was charged with nitrogen at a charging rate of 50 L / min, the pressure was 1000 mbar, and the pressure was maintained for 2 s;

[0013] The formic acid furnace was continuously evacuated to 1 mbar, maintained for 2 seconds, and filled with nitrogen again, maintained for 2 seconds.

[0014] The specific method of heating the formic acid furnace to 180° C., performing a vacuum operation, filling the formic acid furnace with formic acid, heating the formic acid furnace to 220° C. again, and welding the chip to the integrated welding material is as follows:

[0015] The formic acid furnace is heated to 180° C. at a rate of 2° C. / s, and then the heated formic acid furnace is evacuated to 1 mbar;

[0016] Filling nitrogen at a filling rate of 8 L / min and introducing formic acid, when the vacuum degree in the formic acid furnace chamber reaches 600 mbar, filling nitrogen at a filling rate of 50 L / min to fill the vacuum degree to 1000 mbar;

[0017] The formic acid furnace is heated to 220° C. at a speed of 4° C. / min, and then the chip and the integrated welding material are welded.

[0018] The specific method of heating the formic acid furnace to 250° C., evacuating the formic acid furnace, introducing nitrogen, and cooling the formic acid furnace to room temperature to complete the welding of the integrated welding material is as follows:

[0019] The formic acid furnace was heated to 250° C. and maintained at this temperature for 30 seconds;

[0020] The formic acid furnace was evacuated to 1 mbar, and then nitrogen was introduced to fill it to 1000 mbar and maintained for 20 seconds;

[0021] The formic acid furnace is cooled to room temperature to complete the welding of the integrated welding material.

[0022] The specific method of placing the chip and the integrated welding material in the formic acid furnace is:

[0023] The chip and integrated welding material stack are placed on the welding station of the formic acid furnace;

[0024] The formic acid furnace welding temperature and welding time are set based on the chip and the integrated welding material characteristics.

[0025] The specific method of cooling the formic acid furnace to room temperature to complete the welding of the integrated welding material is as follows:

[0026] Cooling the formic acid furnace to room temperature;

[0027] Open the formic acid furnace and take out the chip and the integrated welding material welded at the welding station;

[0028] The weld between the chip and the integrated welding is detected, and the uncompleted integrated welding material is welded again to complete the welding of the integrated welding material.

[0029] The integrated welding material of the present invention, the size, number and length of the filling solder matrix material depend on the actual application situation, which can be one wire, or fill the inside of the filling solder matrix; or several metal wires of different sizes are filled into the solder to achieve the purpose of controlling different heights. The integrated solder can be made into sheets or strips. By adding the metal wires into the filling solder matrix, it is completely integrated into the solder without changing the shape of the solder. After welding, the integrated solder can maintain the wettability and void rate of the filling solder. At the same time, since the filling material has a high melting point, it can provide good supporting force during welding. After welding, the high-melting-point metal wire will form an IMC layer with the filling solder, so that the welded material has better mechanical properties and safety and reliability. There will be no tin overflow during welding, and thus no poor welding. The problem of tin overflow and poor welding caused by existing solder materials when welding some heavier modules is solved. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 It is a schematic diagram of an integrated welding material provided by the present invention.

[0032] Figure 2 It is a SAT diagram of an integrated welding material after welding provided by the present invention.

[0033] Figure 3 This is a cross-sectional morphology diagram of an integrated welding material after welding provided by the present invention.

[0034] Figure 4 This is a SAT diagram of an integrated welding material provided by the present invention under TC test.

[0035] Figure 5 The present invention provides a flow chart of an integrated welding material welding method.

[0036] Figure 6 The invention is a flow chart of a specific method of placing a chip and integrated welding materials in a formic acid furnace, and sequentially performing vacuuming, nitrogen flushing and vacuuming operations on the formic acid furnace.

[0037] Figure 7 It is a flow chart of a specific method of heating the formic acid furnace to 180° C., performing a vacuum operation, filling the formic acid into the formic acid furnace, heating the formic acid furnace to 220° C. again, and welding the chip to the integrated welding material.

[0038] Figure 8 The specific flow chart of the method of heating the formic acid furnace to 250° C., evacuating the formic acid furnace, introducing nitrogen, and cooling the formic acid furnace to room temperature to complete the welding of the integrated welding material. DETAILED DESCRIPTION

[0039] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present invention, and should not be construed as limiting the present invention.

[0040] See also Figure 1 In a first aspect, the present invention provides an integrated welding material, comprising a metal wire and a filler solder matrix, wherein the metal wire comprises one or more of Ag, Au, Pb, Pt, Cu, Ni, Co, Fe, Mn, Mg, Ti, Zr, W and In and alloys thereof, and the filler solder matrix comprises one or more of Sn-based solder, Pb-based solder, In-based solder, Bi-based solder, Zn-based solder, Au-based solder, Cd-based solder and Ga-based solder.

[0041] In the embodiment of the present invention, the size, number and length of the filling solder matrix depend on the actual application situation. It can be one wire, or fill the inside of the filling solder matrix; it can also be several metal wires of different sizes filled into the solder to achieve the purpose of controlling different heights. The integrated solder can be made into sheets or strips. By adding the metal wires into the filling solder matrix, it is completely integrated into the solder without changing the shape of the solder. After welding, the integrated solder can maintain the wettability and void rate of the filling solder. At the same time, due to the high melting point of the filling material, it can provide good support during welding. After welding, the high melting point metal wire will form an IMC layer with the filling solder, so that the welded material has better mechanical properties and safety and reliability. There will be no tin overflow during welding, and thus no poor welding. The problem of tin overflow and poor welding when welding some heavier modules with existing solder materials is solved.

[0042] Second aspect Figure 2-Figure 8 The present invention also provides an integrated welding material welding method, which is applied to the integrated welding material described in the first aspect above, comprising the following steps:

[0043] S1: placing the chip and the integrated welding material in a formic acid furnace, and sequentially performing vacuuming, nitrogen flushing and vacuuming operations on the formic acid furnace;

[0044] In the embodiment of the present invention, the integrated solder uses SnAg3.5 as the filling solder, and the metal wire uses pure copper. The thickness of the integrated solder is 0.2 mm, and a 20*20 mm long and wide solder sheet is formed by stamping. The chip is soldered through the integrated solder sheet and placed in a formic acid furnace for soldering. The formic acid furnace is selected from Beijing Jingfu Huakong Electronic Equipment Co., Ltd., model JFHK-HJL / 100. The oxygen content in the formic acid furnace chamber is greatly reduced by vacuuming and filling with nitrogen twice.

[0045] Specific method:

[0046] S11: placing the chip and the integrated welding material in a formic acid furnace, evacuating the formic acid furnace to 1 mbar, and maintaining the vacuum for 30 seconds;

[0047] Specific method:

[0048] S111: heating the formic acid furnace to 250°C and maintaining the temperature for 30 seconds;

[0049] S112 evacuates the formic acid furnace to 1 mbar, then introduces nitrogen to 1000 mbar, and maintains this for 20 seconds;

[0050] The formic acid furnace is cooled to room temperature to complete the welding of the integrated welding material.

[0051] S12: nitrogen is charged into the formic acid furnace at a charging rate of 50 L / min, the pressure is 1000 mbar, and the pressure is maintained for 2 seconds;

[0052] S13 continues to evacuate the formic acid furnace to 1 mbar, maintains for 2 seconds, and fills with nitrogen again, maintains for 2 seconds.

[0053] S2: heating the formic acid furnace to 180° C., performing a vacuum operation, filling the formic acid furnace with formic acid, heating the formic acid furnace to 220° C. again, and welding the chip to the integrated welding material;

[0054] Specific method:

[0055] S21: heating the formic acid furnace to 180° C. at a rate of 2° C. / s, and then evacuating the heated formic acid furnace to 1 mbar;

[0056] S22: nitrogen is charged at a charging rate of 8 L / min and formic acid is introduced. When the vacuum degree in the formic acid furnace chamber reaches 600 mbar, nitrogen is charged at a charging rate of 50 L / min to raise the vacuum degree to 1000 mbar.

[0057] S23: heating the formic acid furnace to 220° C. at a rate of 4° C. / min, and then welding the chip to the integrated welding material.

[0058] In the embodiment of the present invention, the surface temperature of the welding material is made uniform by slow heating, and the formic acid can better reduce the surface oxide layer under the action of temperature and time.

[0059] S3: heating the formic acid furnace to 250° C., evacuating the formic acid furnace, introducing nitrogen, and cooling the formic acid furnace to room temperature to complete the welding of the integrated welding material.

[0060] Specific method:

[0061] S31: heating the formic acid furnace to 250° C. and maintaining the temperature for 30 seconds;

[0062] S32 evacuates the formic acid furnace to 1 mbar, then introduces nitrogen to 1000 mbar, and maintains this for 20 seconds;

[0063] S33 cools the formic acid furnace to room temperature, completing the welding of the integrated welding material.

[0064] Specific method:

[0065] S331 cools the formic acid furnace to room temperature;

[0066] S332: Open the formic acid furnace and take out the chip and the integrated welding material welded at the welding station;

[0067] S333 detects the weld between the chip and the integrated welding, and re-welds the unfinished integrated welding material to complete the welding of the integrated welding material.

[0068] In the embodiment of the present invention, the SAT diagram after welding ( Figure 2 ), it can be seen that there is no poor wetting and voids, which is consistent with the conventional SnAg3.5 solder, indicating good welding performance. The cross-sectional picture after welding ( Figure 3 ), it can be seen that the filling solder and metal wire form an IMC layer, which is the guarantee for good mechanical properties and cycle reliability.

[0069] According to ECPE Guideline 324 (AQG 324), the power cycle test is carried out with a constant load current of about 250A for each IGBT, a junction temperature difference ΔTj = 100K, a turn-on time ton = 3s, a cooling time toff = 6s, a gate voltage VGE = 15V, and a temperature change from Tmin = 40°C to Tmax = 140°C (machine program control, which is the existing technology). Conventional SnAg3.5 will have voids after more than 1,000 cycles and will basically fail after more than 3,000 cycles, but Figure 4 It can be observed that the solder of the present invention can be cycled 30,000 times and still has good bonding strength.

[0070] What is disclosed above is only a preferred embodiment of an integrated welding material and a welding method of the present invention. Of course, this cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiments and equivalent changes made according to the claims of the present invention are still within the scope of the invention.

Claims

1. An integrated welding material, characterized in that ； It includes a metal wire and a filling solder matrix, wherein the metal wire includes one or more of Ag, Au, Pb, Pt, Cu, Ni, Co, Fe, Mn, Mg, Ti, Zr, W and In and alloys thereof, and the filling solder matrix includes one or more of Sn-based solder, Pb-based solder, In-based solder, Bi-based solder, Zn-based solder, Au-based solder, Cd-based solder and Ga-based solder.

2. A welding method for integrated welding materials, applied to the integrated welding material according to claim 1, characterized in that: The steps include: Placing the chip and the integrated welding material in a formic acid furnace, and sequentially performing vacuuming, nitrogen flushing and vacuuming operations on the formic acid furnace; The formic acid furnace is heated to 180° C., vacuumed, filled with formic acid, heated again to 220° C., and the chip is welded to the integrated welding material; The formic acid furnace is heated to 250° C., and then the formic acid furnace is evacuated, nitrogen is introduced, and the formic acid furnace is cooled to room temperature to complete the welding of the integrated welding material.

3. The integrated welding material welding method according to claim 2, characterized in that; The specific method of placing the chip and the integrated welding material in a formic acid furnace, and sequentially performing vacuuming, nitrogen flushing and vacuuming operations on the formic acid furnace is as follows: The chip and the integrated welding material are placed in a formic acid furnace, and the formic acid furnace is evacuated to 1 mbar and maintained for 30 seconds; The formic acid furnace was charged with nitrogen at a charging rate of 50 L / min, the pressure was 1000 mbar, and the pressure was maintained for 2 s; The formic acid furnace was continuously evacuated to 1 mbar, maintained for 2 seconds, and filled with nitrogen again, maintained for 2 seconds.

4. The integrated welding material welding method according to claim 2, It is characterized by: The specific method of heating the formic acid furnace to 180° C., performing a vacuum operation, filling the formic acid furnace with formic acid, heating the formic acid furnace to 220° C. again, and welding the chip to the integrated welding material is as follows: The formic acid furnace is heated to 180° C. at a rate of 2° C. / s, and then the heated formic acid furnace is evacuated to 1 mbar; Filling nitrogen at a filling rate of 8 L / min and introducing formic acid, when the vacuum degree in the formic acid furnace chamber reaches 600 mbar, filling nitrogen at a filling rate of 50 L / min to fill the vacuum degree to 1000 mbar; The formic acid furnace is heated to 220° C. at a speed of 4° C. / min, and then the chip and the integrated welding material are welded.

5. The integrated welding material welding method according to claim 2, It is characterized by: The specific method of heating the formic acid furnace to 250° C., evacuating the formic acid furnace, introducing nitrogen, and cooling the formic acid furnace to room temperature to complete the welding of the integrated welding material is as follows: The formic acid furnace was heated to 250° C. and maintained at this temperature for 30 seconds; The formic acid furnace was evacuated to 1 mbar, and then nitrogen was introduced to fill it to 1000 mbar and maintained for 20 seconds; The formic acid furnace is cooled to room temperature to complete the welding of the integrated welding material.

6. The integrated welding material welding method according to claim 3, It is characterized by: The specific method of placing the chip and the integrated welding material in the formic acid furnace is: The chip and integrated welding material stack are placed on the welding station of the formic acid furnace; The formic acid furnace welding temperature and welding time are set based on the chip and the integrated welding material characteristics.

7. The integrated welding material welding method according to claim 5, characterized in that; The specific method of cooling the formic acid furnace to room temperature and completing the welding of the integrated welding material is as follows: Cooling the formic acid furnace to room temperature; Open the formic acid furnace and take out the chip and the integrated welding material welded at the welding station; The weld between the chip and the integrated welding is detected, and the uncompleted integrated welding material is welded again to complete the welding of the integrated welding material.

Images