JPS6246066B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a silver or silver alloy coated diode lead wire with improved corrosion resistance and solderability, and a method for manufacturing the same. In addition to the characteristics of the core wire of silver or silver alloy coated wire, it has the excellent corrosion resistance and solderability peculiar to silver.
It is used for various purposes. For example, alloy wires such as Cu, Cu-Ag, Cu-Sn, and Cu-Zn coated with Ag have excellent corrosion resistance and solderability unique to silver, in addition to the mechanical properties and conductivity of the core wire. For this reason, it is widely used as lead wires for electronic components and conductors in electronic devices.
The thickness of the Ag coating is generally about 1 to 10 μm from the viewpoints of corrosion resistance, solderability, and economy. like this
When Ag-coated wire is exposed to a high-temperature environment, the appearance discolors due to the diffusion of Cu in the core wire, which significantly deteriorates solderability. To avoid this, between the core wire and the Ag coating,
Those provided with a Ni or Ni alloy layer have been put into practical use. The Ni or Ni alloy layer acts as a diffusion barrier and prevents the core wire Cu from diffusing into the Ag coating layer.
Even if the Ag coating thickness is thin, surface quality does not deteriorate and it is said to be economical. However, even in the case of diode lead wires that require a certain amount of solder build-up by soldering Ag-coated wires, the solder wets and penetrates actively and quickly spreads in a thin layer, making it difficult to build up the solder. Ta. Furthermore, when exposed to a high temperature environment, oxygen in the atmosphere actively penetrates into the Ag layer, resulting in oxidation of the surface of the Ni or Ni alloy layer, making the Ag layer more likely to peel off, reducing the reliability of the diode lead wire. Not only this, but also the solder strength is reduced. Therefore, the use of a Ni or Ni alloy layer is no longer used in diode lead wires, and those with a thick Ag coating are used instead. In view of this, and as a result of various studies, the present invention has excellent corrosion resistance and solderability, and is easy to apply solder overlay.
We have developed a silver or silver alloy coated diode lead wire and its manufacturing method that can save expensive Ag. The diode lead wire of the present invention has a
In wires with Ag or Ag alloy layer, oxygen-free Cu
Or, a layer of Ni, Co, or an alloy thereof, and a layer of Zn, Sn, In, Cd, or an alloy thereof are sequentially formed on a core wire made of a Cu alloy, and a layer of Ag or an Ag alloy is provided thereon. That is. Additionally, the manufacturing method for diode lead wires is oxygen-free.
After plating Ni, Co or these alloys on a core wire made of Cu or Cu alloy, Zn, Sn, In, Cd or these alloys are plated, and then Ag or Ag
It is characterized by plating the alloy. That is, as shown in FIG. 1, the diode lead wire of the present invention has a core wire 1 made of oxygen-free Cu or Cu alloy.
Ni, Co, or an alloy layer 2 of these is formed on the circumferential surface, a layer 3 of Zn, Sn, In, Cd, or an alloy thereof is formed thereon, and a layer 4 of Ag or an Ag alloy is provided thereon. It is. In addition to Ni and Co, Ni-Co, Ni-P, Ni-B, Ni-
It is made of Sn, Ni-Zn, Co-P, Co-Sn alloy, etc., and a thickness of about 0.1 to 5 μm is sufficient. Zn, Sn, In, Cd or an alloy layer thereof (hereinafter referred to as a second intermediate layer) may include Zn, In, or Cd, such as Zn-Cu, Zn-Cd, Sn-In, Sn-
Pb, Sn-Cu, Sn-Zn, etc., and the second intermediate layer may be formed by laminating any one or two or more of these metals or alloys, and its thickness may be Ag or
It is desirable to set it to 1/500 to 1/10 of the Ag alloy coating thickness. In addition, as an Ag or Ag alloy layer, in addition to Ag,
There are Ag-Cu, Ag-Sb alloys, etc., and the thickness is usually desirably 0.5μ or more. The coated wire of the present invention has the above-mentioned structure, and exhibits appropriate solder wetting and spreading properties without causing abnormal appearance such as discoloration or peeling even with a thin Ag or Ag alloy coating, and without deteriorating solderability. It is easy to apply a suitable amount of solder. These effects are that when soldering a Si chip to the header-processed tip of a lead wire at high temperature, the solder wetting and spreading properties are appropriate, and it is easy to build up solder to hold the chip.
Since the chip portion is then sealed with resin, the solderability of the lead wires will not deteriorate even if processed at high temperatures for a long time. The reason why such an effect is obtained is not necessarily clear, but a part of the second intermediate layer diffuses into Ag or an Ag alloy and becomes alloyed, and the first intermediate layer is absorbed by oxygen in the atmosphere.
It is thought that this prevents surface oxidation of the intermediate layer and also appropriately suppresses solder wetting and spreading. However, if the thickness of the second intermediate layer is less than 1/500 of the Ag or Ag alloy coating thickness, the surface oxidation prevention of the first intermediate layer will be insufficient, and if it exceeds 1/10, the solderability will decrease. become. Such a diode lead wire of the present invention is manufactured as follows. That is, after degreasing and activating the surface of the core wire made of oxygen-free Cu or Cu alloy by normal means, the first intermediate layer, the second intermediate layer, and the Ag or Ag alloy coating layer are successively applied by electroplating or chemical plating. It can be easily manufactured by sequentially forming them. Hereinafter, the present invention will be described in detail with reference to examples. Example 1 Cu wire with a diameter of 0.6 mm is continuously supplied, and the following treatment tank is installed continuously on the line that winds it, and an oxygen-free
A diode lead wire of the present invention was manufactured by successively applying Ni plating to a thickness of 1.0μ, Zn plating to a thickness of 0.05μ, and Ag plating to a thickness of 1.5μ to a Cu wire. (1) Cathode degreasing NaOH 20g/, 10A/dm ² , 10sec (2) Water washing Clear water, 5sec (3) Pickling H ₂ SO ₄ 100g/, 5sec (4) Water washing Clear water, 5sec (5) Ni plating NiSO ₄ 240g/ , NiCl ₂ 50g/, H ₃ BO ₃ 30
g/, bath temperature 40℃, 5A/dm ² , 60sec (6) Water washing Clear water, 5sec (7) Zn plating ZnCN60g/, NaCN40g/, NaOH80
g/, bath temperature RT, 1A/dm ² , 20sec (8) water washing clear water, 5sec (9) Ag Suirikemetsuki AgCN3g/, KCN40g/, bath temperature RT,
10A/dm ² , 3sec (10) Ag plating AgCN50g/, KCN100g/, bath temperature R.
T, 3A/dm ² , 55sec (11) Water washing Fresh water, 10sec (12) Drying example 2 In Example 1, the following treatment tank was installed in place of (5) Ni plating and (7) Zn plating. Approximately 10% Co-Ni alloy plating with a thickness of 0.25μ is applied to the oxygen Cu wire, and the thickness
Approximately 30% Zn-Cu alloy plating of 0.1μ and thickness of 1.5μ
A diode lead wire of the present invention was manufactured by continuously performing Ag plating. (5) Ni-Co alloy plating NiSo ₄ 240g/, CoSo ₄ 15g/, NiCl ₂ 20
g/, H ₃ BO ₄ 30g/, bath temperature 40℃, 0.4A/
dm ² , 30sec (7) Cu-Zn alloy plating CuCN30g/, Zn(CN) ₂ 10g/,
NaCN50g/, NA ₂ CO ₃ 30g/, bath temperature 40
℃, 0.4A/cm ² , 30sec Example 3 In Example 2, the following treatment bath was provided in place of the Cu-Zn alloy plating in (7), and the oxygen-free Cu wire was coated with a thickness of
Approximately 10% Co-Ni alloy plating of 0.25μ and thickness 0.1μ
A diode lead wire of the present invention was manufactured by sequentially performing Sn plating of 1.5 μm and Ag plating of 1.5 μm thick. (7) Sn plating SnSO ₄ 100g/, H ₂ SO ₄ 50g/, β-naphthol 1g/, glue 2g/, bath temperature R.
T, 1A/dm ² , 15sec Example 4 In Example 1, the following treatment bath was installed in place of the Ni plating in (5) and the Zn plating in (7), and the oxygen-free Cu wire was coated with approximately 5% of the thickness of 1.5μ. P-Ni alloy plating and thickness 0.5μ
A diode lead wire of the present invention was manufactured by successively performing In plating and Ag plating to a thickness of 1.5 μm. (5) Ni-P alloy plating NiSO ₄ 180g/, NiCl ₂ 30g/, H ₃ BO ₃ 30
g/, H ₃ PO ₃ 10g/, bath temperature 45℃, 5A/d
m ² , 90sec (7) In (BF ₄ ) ₃ 250g/, H ₃ BO ₄ 15g/,
NH ₄ BF ₄ 50g/, bath temperature RT, 5A/dm ² ,
20sec Example 5 In Example 4, the following treatment tank was installed in place of the In plating in (7), and the oxygen-free Cu wire was coated with approximately 5% of the thickness of 1.5μ.
P-Ni alloy plating and 0.1μ thick Cd plating and thickness
A diode lead wire of the present invention was manufactured by continuously performing 1.5μ Ag plating. (7) Cd Mekki CdCN35g/, NaCN70g/, Na ₂ CO ₃ 40
g/, bath temperature 30℃, 2.5A/dm ² , 6sec Example 6 In Example 4, the following treatment tank was installed in place of the In plating in (7), and the oxygen-free Cu wire was coated with approximately 1.5μ thick %
A diode lead wire of the present invention was manufactured by sequentially performing P--Ni alloy plating, approximately 10% Sn--Cu alloy plating with a thickness of 0.1 .mu.m, and Ag plating with a thickness of 1.5 .mu.m. (7) Cu-Sn alloy plating CuCN30g/, K ₂ SnO ₃ 35g/, KCN70
g/, KOH12g/, Lotsiel salt 30g/
, bath temperature 60℃, 5A/dm ² , 5sec Example 7 In Example 2, the following treatment bath was provided in place of the Ni-Co alloy plating in (5), and the oxygen-free Cu wire was coated with a thickness of 0.3μ.
A diode lead wire of the present invention was manufactured by sequentially performing Co plating of 100%, approximately 30% Zn--Cu alloy plating with a thickness of 0.1μ, and Ag plating with a thickness of 1.5μ. (5) Co-metsuki CoSO ₄ 400g/, NaCl 20g/, H ₃ BO ₃ 45
g/, bath temperature RT, 5 A/dm ² , 18 sec Example 8 In Example 7, the following treatment bath was installed in place of the Ag plating in (10), and the oxygen-free Cu wire was coated with Co plating with a thickness of 0.3μ and A diode lead wire of the present invention was manufactured by successively plating a 3% Zn--Cu alloy with a thickness of 0.1 .mu.m and plating a 2% Sb--Ag alloy with a thickness of 1.5 .mu.m. (10) Ag-Sb alloy plating AgCN12g/, KCN40g/, antimol potassium tartrate 25g/, potassium sodium tartrate 25g/, KOH15g/, bath temperature RT,
4A/dm ² , 40sec Comparative Example 1 In Example 1, Ni plating in (5) and Zn plating in (7) were omitted, and Ag plating with a thickness of 1.5μ was performed on the oxygen-free Cu wire, and the Ag-coated Cu wire was Manufactured. Comparative Example 2 In Comparative Example 1, the Ag plating time in (10) was doubled, and the oxygen-free Cu wire was plated with Ag to a thickness of 3.0 μm to produce an Ag-coated Cu wire. Comparative Example 3 In Comparative Example 1, the Zn plating in (7) was omitted, and the oxygen-free Cu wire was coated with 1.0μ thick Ni plating and 1.5μ thick Ni plating.
Ag-coated Cu wire was manufactured by continuously performing Ag plating. Comparative Example 4 In Comparative Example 3, the Ag plating time in (10) was doubled, and 1.0 μ thick Ni plating and 3.0 μ thick Ag plating were sequentially performed on the oxygen-free Cu wire to coat Ag.
Manufactured Cu wire. For the various diode lead wires manufactured in this way, H ₂
After heat treatment at a temperature of 310℃ in air flow for 15 minutes, heat treatment at a temperature of 250℃ in air for 10 hours, and after each heat treatment, the diode lead wire was placed in a eutectic solder bath heated to a temperature of 240℃ for 2 seconds. The solder adhesion area on the surface was visually compared. In addition, the diode lead wire after both heat treatments was twisted 80 times with a gauge length of 160 mm, and the peeling state of the Ag coating was compared. These results are shown in Table 1.

【table】

[Table] Processing for 15 minutes at a temperature of 310°C in a _H2 gas flow corresponds to soldering of Si chips, and as can be seen from Table 1, all of the products of the present invention had moderate solder adhesion of around 90%. showed his sexuality. In contrast, comparative example products 1 and 2
Samples 3 and 4 have poor solderability, and samples 3 and 4 have excessive solderability and are difficult to build up with solder. Also in the atmosphere
Processing at a temperature of 250℃ for 10 hours corresponds to resin sealing,
This corresponds to the solderability after resin sealing, and all of the products of the present invention are excellent with a score of 80% or more. On the other hand, the solderability of all comparative example products was drastically reduced. In addition, when peeling by twisting after treatment at a temperature of 250° C. in the atmosphere for 10 hours, the samples of the examples of the present invention peeled off only slightly, whereas the samples of the comparative examples all peeled off significantly. Especially comparative example products 3 and 4 with Ni intermediate layer.
The reason why the peeling was significant even in this case is that the surface of the Ni layer was oxidized. Ag with conventional Ni interlayer
Or, even if Ag alloy-coated Cu wire has excellent solderability, it is difficult to build up solder in chip soldering, and furthermore, a thick Ag or alloy coating with a thickness of 5μ or more is required to withstand resin encapsulation. Ta. In contrast, according to the present invention, much thinner Ag
Alternatively, the Ag alloy coating facilitates chip soldering and is resistant to resin sealing, making it easy to assemble the diode, significantly improving productivity, and also having a significant effect in terms of silver savings.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a diode lead wire according to the present invention. 1... Core wire, 2... First intermediate layer, 3... Second intermediate layer, 4... Ag or Ag alloy layer.

Claims (1)

[Claims] 1. A wire in which an Ag or Ag alloy layer is provided on the outermost periphery of the core wire, and a core wire made of oxygen-free Cu or Cu alloy is coated with Ni, Co or an alloy layer thereof, and Zn, Sn, In,
A silver or silver alloy coated diode lead wire, characterized in that a layer of Cd or an alloy thereof is sequentially formed, and a layer of Ag or an Ag alloy is provided thereon. 2. The silver or silver alloy coated diode according to claim 1, wherein the thickness of the Zn, Sn, In, Cd or alloy layer thereof is 1/500 to 1/10 of the thickness of the Ag or Ag alloy layer. Lead. 3 Ni on the core wire made of oxygen-free Cu or Cu alloy,
After plating Co or these alloys, Zn, Sn,
Plating In, Cd or their alloys, and then
A method for producing a silver or silver alloy coated diode lead wire, which comprises plating Ag or an Ag alloy.