CN-115910803-B - Low-temperature bonding method based on hydrophobic copper micron layer

CN115910803BCN 115910803 BCN115910803 BCN 115910803BCN-115910803-B

Abstract

The invention provides a low-temperature bonding method based on a hydrophobic copper micrometer layer, which comprises the steps of firstly electrodepositing a copper micrometer needle layer prepared on a copper substrate, adding a mixture into indium plating liquid, electroplating the copper micrometer needle layer in the indium plating liquid containing the mixture, forming a pine-shaped nanometer indium layer on the surface layer of the copper micrometer needle layer, obtaining a substrate with a pine-shaped copper indium second-level micro-nano layer, uniformly covering graphene on the pine-shaped copper indium second-level micro-nano layer, bonding the graphene with Sn-Ag-Cu alloy solder balls, adding the mixture to enable the indium plating liquid to form the pine-shaped nanometer indium layer on the surface layer of the copper micrometer needle layer, and enabling the shear strength after bonding with solder to be high.

Inventors

XIAO JIN
YAN JICHAO
QU FUKANG
LI WUCHU

Assignees

广州华立学院

Dates

Publication Date: 20260512
Application Date: 20221108

Claims (7)

1. A low-temperature bonding method based on a hydrophobic copper micron layer is characterized by comprising the following steps of: s1, electrodepositing a prepared copper micrometer needle layer on a copper substrate; s2, adding a mixture into the indium plating solution, wherein the mixture comprises electrolyte, polyethylene glycol, jianna green and CI ions; S3, placing the copper microneedle layer in indium plating solution containing the mixture for electroplating, and forming a pine-shaped micro-nano indium layer on the surface layer of the copper microneedle layer; s4, uniformly covering the graphene on the pine-shaped copper-indium second-level micro-nano indium layer; s5, oppositely arranging the pine-shaped copper indium secondary micro-nano indium layer coated with the graphene and the Sn-Ag-Cu alloy solder balls on an ultrasonic bonding instrument, and forming a contact area between the pine-shaped copper indium secondary micro-nano indium layer coated with the graphene and the Sn-Ag-Cu alloy solder balls; and S6, starting an ultrasonic bonding instrument and a loader, and bonding the pine-shaped copper indium second-level micro-nano indium layer coated with the graphene with the Sn-Ag-Cu alloy solder balls.
2. The method for bonding the hydrophobic copper micrometer layer based on S4 is characterized by further comprising the steps of preparing graphene, specifically, depositing synthetic graphene on a copper foil by low-pressure chemical vapor, spin-coating a polymer on the surface of the graphene, shaping, baking a graphene mixture containing the polymer, placing the graphene mixture containing the polymer into a copper etching agent to remove the copper foil, scooping the graphene mixture containing the polymer by using a pine-shaped copper indium secondary micro-nano indium layer substrate plated with the micro-nano indium layer, drying the pine-shaped copper indium secondary micro-nano indium layer substrate carrying the graphene mixture containing the polymer, immersing the pine-shaped copper indium secondary micro-nano indium layer substrate carrying the graphene mixture containing the polymer into xylene to remove the polymer, and transferring the shaped graphene to the pine-shaped copper indium secondary micro-nano indium layer, wherein the polymer is ethylene-vinyl acetate.
3. The method of claim 1, wherein the loading speed of the loader is set to 2.0 mm/min in S6.
4. The method of claim 1, wherein in S6, the bonding pressure of the ultrasonic bonding instrument is set to be 0.5 MPa-0.7 MPa, the bonding frequency is 10KHz-40 KHz, the bonding time is 2S-3S, and the bonding temperature is 100-130 ℃.
5. The method of claim 4, wherein in S6, the bonding pressure of the ultrasonic bonding instrument is set to be 0.6 MPa, the bonding frequency is 20KHz, the bonding time is 2.5S, and the bonding temperature is 120 ℃.
6. The low-temperature bonding method based on the hydrophobic copper micrometer layer, which is disclosed in claim 4, is characterized in that the copper micrometer needle is of a conical structure, the height of the copper micrometer needle is 3-5 μm, the diameter of the needle root is 1-2 μm, and the thickness of the pine-shaped micro-nano indium layer is 250-350 nm.
7. The method for bonding a copper micrometer layer at a low temperature according to claim 1, wherein the indium plating solution containing the mixture is electroplated for 15-20 min.

Description

Low-temperature bonding method based on hydrophobic copper micron layer Technical Field The invention relates to square bonding in three-dimensional packaging in the field of semiconductor devices, in particular to a low-temperature bonding method based on a hydrophobic copper micron layer. Background In electronic packaging, lead-free solder such as tin is generally used for connection with copper, and when the welding temperature of the tin and the copper is higher and the molten tin solder is in direct contact with a bonding pad, the copper and the tin can generate an intermetallic compound, and the higher the brittleness of the intermetallic compound is, the higher the thickness of the intermetallic compound is, the lower the strength of a welding spot is, the strength of a bonding position is reduced, and the packaging reliability is further affected. For example, chinese patent application No. CN202010942868.9, publication No. 2022.10.04, discloses a copper-copper low-temperature bonding method based on graphene/tin modified copper nanoparticles, which uses a composite of copper nanoparticles, tin nanoparticles and graphene micro-sheets as a bonding material, and bonds two copper plating substrates at low temperature. For nickel layers, if a thin pure nickel layer is inserted between copper and tin as a barrier layer, nickel reacts with tin to be rapidly consumed, the thin barrier layer is consumed to be invalid, if an excessively thick nickel layer is inserted between copper and tin, bonding welding reliability is reduced, for Ni-W nickel-based alloy barrier layers, nickel is taken as a main diffusion element, and formed Ni 3Sn4 enables the barrier layer to be subjected to tensile stress, so that the thin barrier layer is cracked, and further the barrier layer is invalid. Disclosure of Invention The invention provides a low-temperature bonding method based on a hydrophobic copper micrometer layer, which is characterized in that a compound agent is added to enable indium plating solution to form a pine-shaped nanometer indium layer on the surface layer of a copper micrometer needle layer, the shearing strength after bonding with solder is high, and graphene is added to avoid direct contact between copper and tin and delay the growth of copper-tin compounds. In order to achieve the aim, the technical scheme of the invention is that the low-temperature bonding method based on the hydrophobic copper micron layer comprises the following steps: s1, electrodepositing the prepared copper micro needle layer on a copper substrate. S2, adding a mixture into the indium plating solution, wherein the mixture comprises electrolyte, polyethylene glycol, jianna green and CI ions. And S3, placing the copper microneedle layer in indium plating solution containing the mixture for electroplating, and forming a pine-shaped micro-nano indium layer on the surface layer of the copper microneedle layer to obtain the copper indium secondary micro-nano indium layer substrate with the pine shape. And S4, uniformly covering the graphene on the pine-shaped copper-indium second-level micro-nano indium layer. S5, the pine-shaped copper indium secondary micro-nano indium layer coated with the graphene and the Sn-Ag-Cu alloy solder balls are oppositely arranged on an ultrasonic bonding instrument, and a contact area is formed between the pine-shaped copper indium secondary micro-nano indium layer coated with the graphene and the Sn-Ag-Cu alloy solder balls. And S6, starting an ultrasonic bonding instrument and a loader, and bonding the pine-shaped copper indium second-level micro-nano indium layer coated with the graphene with the Sn-Ag-Cu alloy solder balls. The method comprises the steps of mixing electrolyte, polyethylene glycol, The electrolyte contains H 2P02- , and as the copper microneedle layer is electroplated In the indium plating solution containing the mixture, H 2P02- is attached to the copper microneedle layer, and is firstly reacted with In 3+ through H 2P02- to enable In 3+ to be deposited on the copper microneedle layer, and meanwhile, the Jianna green is reacted with H 2P02- on the copper microneedle layer to enable H 2P02- to be reduced, excessive reaction between H 2P02- and In 3+ is inhibited, deposition of In 3+ on the copper microneedle layer is inhibited, H 2P02- is reacted with In 3+ to enable the copper microneedle layer to be deposited on the copper microneedle layer, And forming refined grains under the combined action of the reaction of the Jianna green and H 2P02- , and further forming the pine-shaped copper indium secondary micro-nano layer. And then, graphene is arranged on the Sn-Ag-Cu alloy solder ball and the pine-shaped copper indium second-level micro-nano indium layer substrate, so that direct contact between copper and tin is avoided, growth of copper-tin compounds is delayed, tissue aging effect is delayed, dislocation expansion in copper is prevented by adding the graphene, shear