Production process of tinned copper wire

Abstract

The invention discloses a production process of tinned copper wire, relating to the technical field of copper wire production. The tinned copper wire comprises a bare copper wire, a barrier layer and a plating layer. The bare copper wire is oxygen-free copper with a copper content of more than 99.99%. The production process comprises the following steps: pre-treating the bare copper wire, then placing it in a tin solution, fully immersing the copper wire through a tinning eyelet, vertically guiding the tinned copper wire upward, and drying the wire. The invention performs pre-treatment on the surface of the bare copper wire, forms a barrier layer on the surface due to the flaky structure of montmorillonite, thereby avoiding the diffusion problem of the tinning layer. In addition, the conductive gel matrix added therein has a good conductive network structure. Furthermore, the rare earth elements in the added organic rare earth compound can reduce the whisker problem generated in the subsequent tinning process.

Description

Technical Field

[0001] The invention relates to the technical field of copper wire production, in particular to a production process of tinned copper wire. Background Art

[0002] Tinned copper wire is widely used in the electronics industry due to its excellent solderability. During the production process, the amount of tin used is minimized to minimize the thickness of the tin layer, thereby lowering costs. However, this often results in a yellowing of the tin layer.

[0003] It's generally believed that electroplated tin coatings on copper substrates consist of a tin-rich layer, a copper-tin stabilized layer, and a pure tin layer. When the tin coating is too thin, diffusion causes the pure tin coating to become increasingly thinner and eventually disappear completely. The coating's color will also gradually change, appearing light yellow or bluish-yellow. Without a barrier layer between the tin coating and the copper substrate, this diffusion rate will be very rapid during high-temperature drying. Summary of the Invention

[0004] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a production process for tinned copper wire.

[0005] The technical solutions of the present invention are as follows:

[0006] A production process for tinned copper wire, comprising a bare copper wire, a barrier layer and a plating layer; the bare copper wire is oxygen-free copper with a copper content of more than 99.99%;

[0007] The production process includes the following steps:

[0008] The bare copper wire is pretreated and then placed in the tin solution. After being fully immersed, the copper wire is passed through a tinning eye mold, the tinned copper wire is guided vertically upward, and dried.

[0009] The pretreatment comprises: dipping the bare copper wire in a treatment solution and then sintering; the treatment solution comprises a conductive gel matrix and inorganic fillers dispersed in the conductive gel matrix.

[0010] As a preferred embodiment of the present invention, the inorganic filler includes montmorillonite.

[0011] As a preferred embodiment of the present invention, the particle size of the inorganic filler is 10-50 μm.

[0012] As a preferred embodiment of the present invention, the inorganic filler accounts for 1-10 wt % of the treatment liquid.

[0013] As a preferred embodiment of the present invention, the conductive gel matrix comprises a mixture of tyrosine-modified polypyrrole, polyacrylic acid and poly (N-isopropylacrylamide).

[0014] As a preferred embodiment of the present invention, the treatment solution further comprises a rare earth organic compound. As a preferred embodiment of the present invention, the sintering temperature is 400-600°C.

[0015] As a preferred embodiment of the present invention, a reflow treatment is further performed after the drying, the reflow temperature is 150-195° C., and the holding time is 10-20 minutes.

[0016] The beneficial effects of the present invention are:

[0017] (1) The present invention provides a production process for tinned copper wire. Pretreatment is performed on the surface of the bare copper wire. Due to the flaky structure of montmorillonite, a barrier layer is formed on the surface, thereby avoiding the diffusion problem of the tinned layer. In addition, the conductive gel matrix added thereto has a good conductive network structure. Furthermore, the rare earth elements in the organic rare earth compound added thereto can reduce the whisker problem generated during the subsequent tinning process.

[0018] (2) In the production process of tin-plated copper wire of the present invention, the melting point of tin is 232°C. If the reflow temperature is higher than this, tin beads will be produced and the porosity will increase. Therefore, reflow treatment at 150-190°C can reduce its stress, improve the bonding strength of the coating, and reduce the porosity. DETAILED DESCRIPTION

[0019] The technical solution of the present invention is further described below with reference to specific embodiments.

[0020] Example 1

[0021] A production process for tinned copper wire, comprising a bare copper wire, a barrier layer and a plating layer; the bare copper wire is oxygen-free copper with a copper content of more than 99.99%;

[0022] The production process includes the following steps:

[0023] The bare copper wire is pretreated and then placed in the tin solution. After being fully immersed, the copper wire is passed through a tinning eye mold, the tinned copper wire is guided vertically upward, and dried.

[0024] The pretreatment comprises: dipping the bare copper wire in a treatment solution and then sintering; the treatment solution comprises a conductive gel matrix and inorganic fillers dispersed in the conductive gel matrix.

[0025] The inorganic filler includes montmorillonite.

[0026] The particle size of the inorganic filler is 33 μm.

[0027] The inorganic filler accounts for 3 wt % of the treatment liquid.

[0028] The conductive gel matrix comprises a mixture of tyrosine-modified polypyrrole, polyacrylic acid and poly-N-isopropylacrylamide in a mass ratio of 1:1:4.

[0029] The treatment solution also includes rare earth organic compounds. Specifically (Ce 3+ )-isophthalic acid-o-phenanthroline.

[0030] The sintering temperature is 400°C.

[0031] After the drying, a reflow treatment is performed, with a reflow temperature of 155° C. and a holding time of 12 minutes.

[0032] Example 2

[0033] A production process for tinned copper wire, comprising a bare copper wire, a barrier layer and a plating layer; the bare copper wire is oxygen-free copper with a copper content of more than 99.99%;

[0034] The production process includes the following steps:

[0035] The bare copper wire is pretreated and then placed in the tin solution. After being fully immersed, the copper wire is passed through a tinning eye mold, the tinned copper wire is guided vertically upward, and dried.

[0036] The pretreatment comprises: dipping the bare copper wire in a treatment solution and then sintering; the treatment solution comprises a conductive gel matrix and inorganic fillers dispersed in the conductive gel matrix.

[0037] The inorganic filler includes montmorillonite.

[0038] The particle size of the inorganic filler is 40 μm.

[0039] The inorganic filler accounts for 3 wt % of the treatment liquid.

[0040] The conductive gel matrix comprises a mixture of tyrosine-modified polypyrrole, polyacrylic acid and poly-N-isopropylacrylamide in a mass ratio of 1:1:3.

[0041] The treatment solution also includes rare earth organic compounds. Specifically (Ce 3+ )-isophthalic acid-o-phenanthroline.

[0042] The sintering temperature is 450°C.

[0043] After the drying, a reflow treatment is performed, with a reflow temperature of 165° C. and a holding time of 19 minutes.

[0044] Example 3

[0045] A production process for tinned copper wire, comprising a bare copper wire, a barrier layer and a plating layer; the bare copper wire is oxygen-free copper with a copper content of more than 99.99%;

[0046] The production process includes the following steps:

[0047] The bare copper wire is pretreated and then placed in the tin solution. After being fully immersed, the copper wire is passed through a tinning eye mold, the tinned copper wire is guided vertically upward, and dried.

[0048] The pretreatment comprises: dipping the bare copper wire in a treatment solution and then sintering; the treatment solution comprises a conductive gel matrix and inorganic fillers dispersed in the conductive gel matrix.

[0049] The inorganic filler includes montmorillonite.

[0050] The particle size of the inorganic filler is 42 μm.

[0051] The inorganic filler accounts for 4 wt % of the treatment liquid.

[0052] The conductive gel matrix comprises a mixture of tyrosine-modified polypyrrole, polyacrylic acid and poly-N-isopropylacrylamide in a mass ratio of 1:3:1.

[0053] The treatment solution also includes rare earth organic compounds. Specifically (Ce 3+ )-isophthalic acid-o-phenanthroline.

[0054] The sintering temperature is 400°C.

[0055] After the drying, a reflow treatment is performed, the reflow temperature is 150-195° C., and the holding time is 15 minutes.

[0056] Example 4

[0057] A production process for tinned copper wire, comprising a bare copper wire, a barrier layer and a plating layer; the bare copper wire is oxygen-free copper with a copper content of more than 99.99%;

[0058] The production process includes the following steps:

[0059] The bare copper wire is pretreated and then placed in the tin solution. After being fully immersed, the copper wire is passed through a tinning eye mold, the tinned copper wire is guided vertically upward, and dried.

[0060] The pretreatment comprises: dipping the bare copper wire in a treatment solution and then sintering; the treatment solution comprises a conductive gel matrix and inorganic fillers dispersed in the conductive gel matrix.

[0061] The inorganic filler includes montmorillonite.

[0062] The particle size of the inorganic filler is 35 μm.

[0063] The inorganic filler accounts for 6 wt % of the treatment liquid.

[0064] The conductive gel matrix comprises a mixture of tyrosine-modified polypyrrole, polyacrylic acid and poly-N-isopropylacrylamide in a mass ratio of 1:2:1.

[0065] The treatment solution also includes rare earth organic compounds. Specifically (Ce 3+ )-isophthalic acid-o-phenanthroline.

[0066] The sintering temperature is 450°C.

[0067] After the drying, a reflow treatment is performed, with a reflow temperature of 185° C. and a holding time of 18 minutes.

[0068] Example 5

[0069] A production process for tinned copper wire, comprising a bare copper wire, a barrier layer and a plating layer; the bare copper wire is oxygen-free copper with a copper content of more than 99.99%;

[0070] The production process includes the following steps:

[0071] The bare copper wire is pretreated and then placed in the tin solution. After being fully immersed, the copper wire is passed through a tinning eye mold, the tinned copper wire is guided vertically upward, and dried.

[0072] The pretreatment comprises: dipping the bare copper wire in a treatment solution and then sintering; the treatment solution comprises a conductive gel matrix and inorganic fillers dispersed in the conductive gel matrix.

[0073] The inorganic filler includes montmorillonite.

[0074] The particle size of the inorganic filler is 40 μm.

[0075] The inorganic filler accounts for 8 wt % of the treatment liquid.

[0076] The conductive gel matrix comprises a mixture of tyrosine-modified polypyrrole, polyacrylic acid and poly-N-isopropylacrylamide in a mass ratio of 1:1:2.

[0077] The treatment solution also includes rare earth organic compounds. Specifically (Ce 3+ )-isophthalic acid-o-phenanthroline.

[0078] The sintering temperature is 550°C.

[0079] After the drying, a reflow treatment is performed, with a reflow temperature of 195° C. and a holding time of 20 minutes.

[0080] Comparative Example 1 (without pretreatment)

[0081] A production process for tinned copper wire, comprising a bare copper wire, a barrier layer and a plating layer; the bare copper wire is oxygen-free copper with a copper content of more than 99.99%;

[0082] The production process includes the following steps:

[0083] The bare copper wire is placed in tin liquid, fully immersed, passed through a tinning eyelet, and the tinned copper wire is guided vertically upward, and then dried. After drying, a soft flow treatment is performed, the soft flow temperature is 165° C., and the holding time is 19 minutes.

[0084] Comparative Example 2 (without rare earth organic compound)

[0085] A production process for tinned copper wire, comprising a bare copper wire, a barrier layer and a plating layer; the bare copper wire is oxygen-free copper with a copper content of more than 99.99%;

[0086] The production process includes the following steps:

[0087] The bare copper wire is pretreated and then placed in the tin solution. After being fully immersed, the copper wire is passed through a tinning eye mold, the tinned copper wire is guided vertically upward, and dried.

[0088] The pretreatment comprises: dipping the bare copper wire in a treatment solution and then sintering; the treatment solution comprises a conductive gel matrix and inorganic fillers dispersed in the conductive gel matrix.

[0089] The inorganic filler includes montmorillonite.

[0090] The particle size of the inorganic filler is 40 μm.

[0091] The inorganic filler accounts for 3 wt % of the treatment liquid.

[0092] The conductive gel matrix comprises a mixture of tyrosine-modified polypyrrole, polyacrylic acid and poly-N-isopropylacrylamide in a mass ratio of 1:1:3.

[0093] The sintering temperature is 450°C.

[0094] After the drying, a reflow treatment is performed, with a reflow temperature of 165° C. and a holding time of 19 minutes.

[0095] Comparative Example 3 (without reflow treatment)

[0096] A production process for tinned copper wire, comprising a bare copper wire, a barrier layer and a plating layer; the bare copper wire is oxygen-free copper with a copper content of more than 99.99%;

[0097] The production process includes the following steps:

[0098] The bare copper wire is pretreated and then placed in the tin solution. After being fully immersed, the copper wire is passed through a tinning eye mold, the tinned copper wire is guided vertically upward, and dried.

[0099] The pretreatment comprises: dipping the bare copper wire in a treatment solution and then sintering; the treatment solution comprises a conductive gel matrix and inorganic fillers dispersed in the conductive gel matrix.

[0100] The inorganic filler includes montmorillonite.

[0101] The particle size of the inorganic filler is 40 μm.

[0102] The inorganic filler accounts for 3 wt % of the treatment liquid.

[0103] The conductive gel matrix comprises a mixture of tyrosine-modified polypyrrole, polyacrylic acid and poly-N-isopropylacrylamide in a mass ratio of 1:1:3.

[0104] The treatment solution also includes rare earth organic compounds. Specifically (Ce 3+ )-isophthalic acid-o-phenanthroline.

[0105] The sintering temperature is 450°C.

[0106] The above examples and comparative examples were subjected to performance tests, and the test methods and results are as follows:

[0107] The test method for solderability of tinned copper wire refers to J-STD-002; the test results are shown in Table 1.

[0108]

[0109]

[0110] As can be seen from the table above, the performance of the embodiment is better than that of the comparative example. The main reasons may be as follows: the analysis of comparative example 1 shows that the embodiment performs pretreatment on the surface of the bare copper wire. Due to the flaky structure of montmorillonite, a barrier layer is formed on its surface, which avoids the diffusion problem of the tin plating layer. In addition, the conductive gel matrix added therein has a good conductive network structure. The analysis of comparative example 2 shows that the rare earth elements in the organic rare earth compound added in the embodiment can reduce the whisker problem generated in the subsequent tin plating process. The analysis of comparative example 3 shows that since the melting point of tin is 232°C, if the reflow temperature is higher than it, tin beads will be generated and the porosity will increase. Therefore, reflow treatment at 150-190°C can reduce its stress, improve the bonding strength of the coating, reduce the porosity, and improve.

[0111] Under the premise that no conflict occurs, those skilled in the art may freely combine and superimpose the above-mentioned additional technical features.

[0112] The above description is only a preferred embodiment of the present invention. Any technical solution that achieves the purpose of the present invention by substantially the same means shall fall within the protection scope of the present invention.

Claims

1. A production process for tinned copper wire, characterized in that: The tinned copper wire comprises a bare copper wire, a barrier layer and a plating layer; the bare copper wire is oxygen-free copper with a copper content of more than 99.99%. The production process includes the following steps: The bare copper wire is pretreated and then placed in the tin solution. After being fully immersed, the copper wire is passed through a tinning eye mold, the tinned copper wire is guided vertically upward, and dried. The pretreatment comprises: dipping the bare copper wire in a treatment solution and then sintering; the treatment solution comprises a conductive gel matrix and an inorganic filler dispersed in the conductive gel matrix; the inorganic filler comprises montmorillonite, and the treatment solution further comprises a rare earth organic compound, wherein the rare earth organic compound is (Ce 3+ )-isophthalic acid-o-phenanthroline; The conductive gel matrix comprises: a mixture of tyrosine-modified polypyrrole, polyacrylic acid and poly-N-isopropylacrylamide; After the drying, a reflow treatment is performed, wherein the reflow temperature is 150-195° C. and the holding time is 10-20 minutes.

2. The production process of tinned copper wire according to claim 1, characterized in that: The particle size of the inorganic filler is 10-50 μm.

3. The production process of tinned copper wire according to claim 1, characterized in that: The inorganic filler accounts for 1-10 wt % of the treatment liquid.

4. The production process of tinned copper wire according to claim 1, characterized in that: The sintering temperature is 400-600°C.

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