A one-step process for chip welding of stacked products

Abstract

The present invention relates to a one-step chip welding process for stacked products, the method comprising the following steps: 1) inserting a wire into a welding boat hole to complete the wire arrangement operation on the welding boat; 2) placing a platform fixture at the lower end of the wire, the platform fixture lifts the wire to ensure that the reserved depth of the welding boat hole is 3±1mm; 3) directly implanting the chip into the welding boat with the wire arranged behind; 4) sending the welding boat with the chip arranged into a sintering furnace for welding; 5) the chip after welding is successively packaged, electroplated, tested, packaged, and finally shipped. The process method of the present invention changes the practice of pre-welding in the traditional stacked chip product welding process, omits the pre-welding boat, does not need to stack two chips before formal welding, reduces the process of entering the sintering furnace once, avoids the risk of oxidation of the upper and lower surfaces of the stacked chip, and avoids the risk of material breaking, saves processes, and improves production efficiency.

Description

Technical Field

[0001] The invention relates to a one-step process method for chip welding of a stacked product, belonging to the technical field of chip packaging. Background Art

[0002] In the packaging process of electronic products, if the chip of the stacked product is directly implanted into the welding boat hole, the chip will tilt due to the hole depth, resulting in the upper and lower chips being out of center, so the chip needs to be pre-welded first.

[0003] For example, Chinese patent document CN111739812A discloses a production process for a high-power axial bidirectional diode, which includes the following steps: copper particle pre-soldering: square copper particles and copper particles are welded by welding pieces to form pre-welded copper particles; chip pre-soldering: copper particles and square chips are welded by welding pieces to form pre-welded chips; lower mold filling: first fill the lower lead in the lower mold, and then fill the square chip, pre-welded chip, and pre-welded copper particles in a positive or reverse order, and separate them with welding pieces; upper mold filling: fill the upper lead in the upper mold, and there is a welding piece between the upper lead and the square chip or pre-welded copper particle in the lower mold; mold closing and welding: close the upper mold and the lower mold, press them tightly, and send them into a welding furnace for welding.

[0004] Chinese patent document CN201979244U discloses an SMA one-time welding graphite boat, which includes a graphite plate, a limiting block is set on the long side edge of the graphite plate, and a limiting groove matching the chip is provided between adjacent limiting blocks, and the limiting groove and the limiting block form a serrated shape. Countersunk holes are provided on the graphite plate. The utility model only needs to weld the chip once, which reduces production costs and improves work efficiency; the chip is not offset during welding, and the chip is not offset after welding, the welding state is good, and the quality of the product is guaranteed. The utility model is mainly used for electronic equipment encapsulated with semiconductor power devices.

[0005] The traditional method is to pre-implant two or more chips into a pre-welding boat, and then send the chips and the pre-welding boat to a welding furnace for pre-welding of the chips. The purpose is to ensure that the two stacked chips are concentric, and then assemble the pre-welded chip products, and then send the assembled products to a welding furnace for welding. After welding, they are packaged, electroplated, tested, packaged, and shipped in sequence. Because this traditional method requires an additional step in the welding furnace for pre-welding of the chips before formal welding, and because the upper surface of the upper chip and the lower surface of the lower chip are exposed when the two chips are stacked, the metal layers of the upper and lower surfaces are inevitably oxidized after passing through the high temperature zone of the sintering furnace when entering the welding furnace for pre-welding. This oxidation layer directly affects the quality of the product after assembly and welding, and the risk of material breakage is uncontrollable and the production efficiency is low. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention provides a one-step process method for chip welding of stacked products. The process method does not require pre-welding of two or more chips, thus avoiding the problem of oxidation of the metal layers on the upper and lower surfaces of the chips after pre-welding. At the same time, it avoids the risk of material breakage, saves process steps, and improves production efficiency.

[0007] The technical solution of the present invention is as follows:

[0008] A one-step process for chip welding of a stacked product comprises the following steps:

[0009] 1) Insert the wire into the hole of the welding boat to complete the wire arrangement operation on the welding boat;

[0010] 2) Place a platform fixture at the lower end of the wire, and the platform fixture will lift the wire to ensure that the reserved depth of the welding boat hole is 3±1mm;

[0011] 3) Implant the chip directly into the soldering boat with the wires facing backwards;

[0012] 4) Send the soldering boat with the chips arranged into the sintering furnace for soldering;

[0013] 5) After welding, the chip is packaged, electroplated, tested, packaged and finally shipped.

[0014] Preferably, in step 1), the conductor is an oxygen-free copper wire specially used for matching laminations, with a wire diameter of 0.60 mm.

[0015] Preferably, in step 1), when the wire is inserted into the welding boat hole, it is required that: the end of the wire with the nail head is at the top, and the end without the nail head is at the bottom.

[0016] Preferably, in step 1), the welding boat is made of graphite, and a welding boat with a positioning function is selected.

[0017] Preferably, in step 2), the platform jig is a flat plate with a length of 205 mm, a width of 97 mm, and a height of 28 mm. The platform jig is placed between the legs at both ends of the welding boat, and the wire is lifted up by the platform jig.

[0018] Preferably, in step 3), the chip is implanted into the soldering boat using a suction cup in an environment with a temperature of 25±5° C. and a humidity of ≤60%.

[0019] Technical features and beneficial effects of the present invention:

[0020] 1. The process method of the present invention changes the practice of pre-welding in the traditional welding process of stacked chip products, omits the pre-welding boat, and does not need to perform stacking and pre-welding of two chips before formal welding, thereby reducing the process of entering the sintering furnace once, avoiding the risk of oxidation of the upper and lower surfaces of the stacked chips, and avoiding the risk of material breakage, saving processes, and improving production efficiency.

[0021] 2. The process method of the present invention uses the cooperation of the welding boat and the platform fixture. The platform fixture lifts the lower end of the wire to keep the welding boat hole at a reasonable depth to avoid the two stacked chips being out of center when stacked. This process method can save steps and improve production efficiency, and can also improve the yield rate of chip welding, with obvious effects and remarkable results. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the process flow chart of the traditional process method;

[0023] Figure 2 This is a process flow chart of the one-step chip welding method of the present invention;

[0024] Figure 3 Schematic diagram of the welding boat structure used in the present invention;

[0025] Figure 4 It is a schematic diagram of the structure of the platform fixture used in the present invention;

[0026] Figure 5 It is a structural schematic diagram of the cooperation between the platform fixture and the welding boat in the present invention;

[0027] In the figure: 1-graphite body, 2-welding boat hole, 3-positioning hole, 4-positioning pin, 5-support foot, 6-platform fixture, 7-wire. DETAILED DESCRIPTION

[0028] The present invention will be further described below by way of embodiments in conjunction with the accompanying drawings, but is not limited thereto.

[0029] Embodiment 1:

[0030] like Figure 2 As shown, this embodiment provides a one-step process method for chip welding of stacked products, and the specific operation process includes the following steps:

[0031] 1) Insert the wire into the welding boat hole 2 to complete the wire arrangement operation on the welding boat;

[0032] The conductor 7 is oxygen-free copper wire specially used for lamination, with a wire diameter of 0.60mm, and a special conductor arrangement machine is used to complete the conductor arrangement operation. When the conductor is inserted into the welding boat hole, the requirement is: the end of the conductor with the nail head is on the top, and the end without the nail head is on the bottom.

[0033] The welding boat is made of graphite and is equipped with a positioning function. Figure 3 As shown, it comprises a graphite body 1 and two side legs 5 , and four positioning holes 3 are symmetrically arranged on two sides of the graphite body 1 , wherein positioning pins 4 are installed in the positioning holes on the diagonal lines.

[0034] 2) Place a platform fixture 6 at the lower end of the wire, and the platform fixture 6 lifts the wire to ensure that the reserved depth of the welding boat hole 2 is 3±1mm;

[0035] According to the depth of the reserved boat hole 2, different heights of the platform jig 6 are placed. In this embodiment, the platform jig 6 is a flat plate with a length of 205 mm, a width of 97 mm, and a height of 28 mm. The platform jig 6 is placed between the legs 5 at both ends of the welding boat, and the wire 7 is lifted by the platform jig 6.

[0036] 3) Directly implant the chip into the soldering boat with the wires arranged backwards; during the implantation process, implant the chip into the soldering boat with the help of a suction cup, which can be used for daily production. In an environment with a temperature of 25±5°C and a humidity of ≤60%, implant the chip into the soldering boat with the suction cup.

[0037] 4) Send the soldering boat with the chips arranged into the sintering furnace for soldering;

[0038] 5) After welding, the chip is packaged, electroplated, tested, packaged and finally shipped.

[0039] Compared with the traditional process, the entire operation process of this process does not need to pre-weld the two chips before the formal welding, which reduces the process of entering the sintering furnace once, avoids the risk of oxidation of the upper and lower surfaces of the stacked chips, and avoids the risk of material breakage, saving processes and improving production efficiency.

[0040] The above description is only a specific implementation mode of the present invention, and the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by any technician familiar with the technical field within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention.

Claims

1. A one-step process for chip welding of stacked products, characterized in that: The following steps are involved: 1) Insert the wire into the hole of the welding boat and complete the wire alignment operation on the welding boat; when inserting the wire into the hole of the welding boat, the requirements are: the end of the wire with the nail head is on the top, and the end without the nail head is on the bottom; the welding boat is made of graphite, and a welding boat with positioning function is selected; 2) Place a platform fixture at the lower end of the wire, and the platform fixture will lift the wire to ensure that the reserved depth of the welding boat hole is 3±1mm; The platform fixture uses a flat plate with a length of 205mm, a width of 97mm, and a height of 28mm. The platform fixture is placed between the legs at both ends of the welding boat, and the wire is lifted up by the platform fixture. 3) Implant the chip directly into the soldering boat with the wires facing backwards; 4) Send the soldering boat with arranged chips into the sintering furnace for soldering operation; 5) After welding, the chip is packaged, electroplated, tested, packaged and finally shipped.

2. The one-step chip welding process of the stacked product according to claim 1, characterized in that: In step 1), the conductor is an oxygen-free copper wire specially used for lamination, with a wire diameter of 0.60 mm.

3. The one-step chip welding process of the stacked product according to claim 1, characterized in that: In step 3), the chip is implanted into the soldering boat using a suction cup in an environment with a temperature of 25±5°C and a humidity of ≤60%.

Images