JPH10261754A - Blank sheet for terminal and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain high corrosion resistance by covering the surface of a board composed of Fe based alloy with a surface layer of Pd or the like, regarding a blank sheet plate becoming a terminal member of a lead frame or the like. SOLUTION: In blank sheets 8, 10 for terminals, at least one surface of a board 1 composed of Fe-Ni based alloy or Fe-Cr based alloy is covered with a surface layer 6 for bonding which is composed of Pd or the like via substratum layers 2, 4 composed of Cu, Ni, etc. For obtaining the blank sheet plate 8 or the like, a manufacturing method is contained wherein the surfaces of the board 1 are covered with the substratum layers 2, 4 by using plating, the obtained intermediate blank sheet 3 is subject to cold rolling, and the surfaces of the substratum layers 2, 4 are covered with the surface layers 6 for bonding by using plating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to corrosion resistance used to obtain various electronic and electric parts and terminal materials for connection of electronic and electric equipment, such as lead frames in integrated circuits and wiring boards using semiconductor elements. The present invention relates to an excellent terminal plate and a method of manufacturing the same.

[0002]

2. Description of the Related Art Generally, an Fe-Ni alloy containing 42% of Ni (nickel) or a Cu (copper) alloy is used as a material of a lead frame as a terminal material. Then, when mounting on a wiring board or connecting to a motherboard such as a printed circuit board, a lead frame protruding from the integrated circuit or the like and a connection terminal on the motherboard or the like are soldered when mounted on an integrated circuit or the like. Are electrically connected to each other. in this case,
The surface of the outer lead to be soldered in the lead frame is previously coated with solder by plating or the like.

On the other hand, recently, from the viewpoint of environmental protection, Pb
There has been a movement to restrict the use of (lead), and soldering including such Pb may be avoided. For this reason, coating of a brazing material other than solder on the surface of the outer lead in the lead frame has been studied. For example, by forming a bonding surface layer in which Pd (palladium) is thinly coated by plating or the like on the surface of a lead frame made of a Cu-based or Ni-based alloy, the connection on the motherboard side using various brazing materials. It has been attempted to braze the terminal for use.

However, Fe-30 to 50% Ni
When Pd is plated on the surface of a lead frame made of an Fe-based alloy or an Fe-based alloy such as Fe-6 to 16% Cr,
Since the plating layer of d has a porous structure, corrosion may occur. This corrosion is caused by the Fe
The cause is a corrosion battery formed due to a large potential difference between the base alloy and the Pd plating layer. That is, the potential of Fe
Is base and Pd is noble, and if there is a conductor such as moisture in the porous structure of the Pd plating layer that conducts the two, a so-called corrosion battery is formed between these three members. Hydrogen gas is generated from Pd
Fe ²⁺ is eluted from the surface of the alloy and the Fe alloy is corroded.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the prior art and provides a joining surface layer made of Pd or the like on the surface of a terminal plate such as a lead frame made of an Fe-based alloy. It is an object of the present invention to provide a coated terminal plate excellent in corrosion resistance and a method for producing the same.

[0006]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method for joining Pd or the like to the surface of a terminal material such as a lead frame made of an Fe-based alloy via an underlayer of Cu or the like. This was made with the idea of coating the surface layer. That is, the terminal plate of the present invention is a Fe-Ni-based
Or a substrate made of an Fe—Cr alloy, and Cu, Ni, Sn, Au, or Ag on at least one surface of the substrate.
And a bonding surface layer made of a metal belonging to the platinum group such as Pd or an alloy based on these metals, via an underlayer made of at least one of the above.

[0007] The thickness of the underlayer may be at least 0.1 mm.
A terminal plate having a thickness of 3 μm or more, or a terminal plate having a thickness of the bonding surface layer of at least 0.03 μm is also included. If the underlayer is less than 0.3 μm, it is difficult to prevent the formation of the corrosion battery, and if the surface layer is less than 0.03 μm, the bonding (wetting) property with the brazing material may be insufficient. According to these structures, the Fe-based substrate and the P
Since the corrosion battery between the bonding surface layer such as d and the like is eliminated, a terminal plate having excellent corrosion resistance can be provided. In addition, since the bonding surface layer is coated uniformly and thinly, the bonding surface layer can be easily and reliably bonded to the mating connection terminal using various brazing materials. The upper limit of the thickness of the underlayer is 5 μm or less, preferably 3 μm or less. Further, it is desirable that the structure of the underlayer is dense,
The proportion occupied by pores and the like inside the tissue is 10% or less in area ratio, and more preferably 5% or less. Further, the upper limit of the thickness of the surface layer is 0.5 μm or less, preferably 0.3 μm.
It is as follows. The overall thickness of the terminal plate is 0.1 mm.
Within a range of 0.5 mm to 0.5 mm.

[0008] Further, in order to obtain the terminal plate, the Fe-
Cu, Ni, Sn, Au, or Ag is formed on at least one surface of a substrate made of a Ni-based or Fe-Cr-based alloy.
And then subjecting the obtained intermediate base plate to cold rolling at a rolling reduction of 5% or more, and then forming a platinum group such as Pd on the surface of the base layer. And a method for producing a base plate for a terminal, wherein the surface layer for joining is coated by plating a metal belonging to the above or an alloy based on these metals. According to such a configuration,
The porous underlayer formed by plating presses the internal pores, and covers the surface with a bonding surface layer in a state of a dense and uniform thickness. For this reason, since the underlayer is thinly and uniformly and densely coated between the substrate and the bonding surface layer, it is possible to reliably prevent or suppress the formation of the conventional corrosion battery.

The reason why the rolling reduction of the cold rolling is set to 5% or more is that if the rolling reduction is less than 5%, pores remain in the underlayer and the corrosion cell can be formed between the substrate and the surface layer. This is to prevent this. Therefore, the desired rolling reduction is 10% or more, more preferably 20% or more, and most preferably 50%.
That is all. In addition, although electroplating is mainly used for the plating, hot dipping plating and vapor phase plating are also included. In addition, a manufacturing method in which after the above-mentioned cold rolling, diffusion annealing is further performed in a vacuum or in an inert gas such as Ar is included. According to this, the underlayer and the substrate are mutually diffused at the contact surface between them, and Cu or the like of the underlayer penetrates into the substrate to reduce the potential difference between the two, and the corrosion resistance is further improved, and the surface layer is also improved. A stable coating state can be obtained. The annealing is performed at about 700 to 1100 ° C. for about 1 to 30 minutes.

[0010]

Preferred embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a production process for obtaining a terminal plate of the present invention. As shown in FIG. 1A, an Fe-Ni-based or Fe-Cr-based alloy adjusted to a predetermined composition is melted by vacuum melting or the like to obtain an ingot of a predetermined shape (Step 1, hereinafter referred to as S1). ). Then 1
Approximately 20mm
(S2). The scale formed on the surface of the thick plate is removed by a glander, pickling, or the like (S3), and then heated again to 1000 ° C. or higher and subjected to hot rolling to form a thin plate having a thickness of several mm (S4). After the scale on the surface of the thin plate is removed again (S5), cold rolling (S6) and annealing (S7) for removing the internal strain due to the rolling are repeated for a required number of times, as shown in FIG. 2 (A). Substrate 1 with a thickness of about 0.5mm
Get.

On one or both surfaces of the substrate 1, Cu, N
An underlayer made of at least one of i, Sn, Au, and Ag is coated, for example, by electrolytic plating (S8) to form an underlayer 2 (see FIG. 2B). Intermediate blank 3 obtained
Is subjected to cold rolling (S9) with a rolling reduction of 5% or more, and the porous underlying layer 2 formed by the plating is pressed while pressing the internal holes.
Thin and dense. Next, Pd is applied to the surface of the underlayer 2.
By plating a metal belonging to the platinum group or an alloy based on such a metal, for example, by electrolytic plating (S10), the joining surface layer 6 is covered to obtain the base plate 8 for a terminal.
(See FIG. 2 (C)). Alternatively, as shown in FIG. 1 (B), after the cold rolling (S9) is performed, a vacuum or Ar, N ₂ , H ₄
Diffusion annealing (S11) in an inert gas such as
Are diffused with each other at the contact surface between the substrate and the substrate 1 to moderate the gradient concentration of the composition between the two, and then the surface of the underlayer 2 is plated with Pd or the like (S12) to form the bonding surface layer 6 By coating, the base plate for terminal 8 can be obtained.

As described above, the terminal base plate 8 of the present invention comprises:
Since the underlayer 2 having a dense structure made of Cu or the like is interposed between the substrate 1 made of an Fe-Ni or Fe-Cr alloy and the bonding surface layer 6 made of Pd or the like, The potential difference between the layers 6 is reduced in two stages, and the formation of a conventional corrosion battery can be reliably prevented. Therefore, it is possible to provide a terminal material having excellent corrosion resistance over a long period of time even under various environments. Further, as shown in FIG. 2 (D), after further plating an underlayer 4 of a different metal or alloy on the surface of the underlayer 2, cold rolling (S9) as described above, and After annealing (S11), as shown in FIG. 2 (E), it is also possible to obtain the terminal plate 10 in which the joining surface layer 6 is covered by plating (S10, 12) of Pd or the like. A terminal material having more excellent corrosion resistance by coating the two underlayers 2 and 4 or more underlayers in such an order as to gradually relax the underlayer according to the potential difference between the substrate 1 and the surface layer 6. Can also be provided.

[0013]

EXAMPLES In the following, specific examples of the present invention will be described, and corrosion resistance and the like will be compared with comparative examples. First, as an Fe-Ni alloy, C: 0.014
%, Si: 0.24%, Mn: 0.51%, P: 0.00
An alloy material adjusted to a composition of 2%, Ni: 41.8%, balance: Fe was vacuum melted (S1) to form an ingot of a predetermined shape. This ingot was heated to 1100 ° C. and subjected to hot forging (S2) to form a thick plate having a thickness of 20 mm and a width of 50 mm. Next, the oxide scale adhering to the surface of the thick plate was removed by a grinder (S3), and then heated to 1100 ° C. and subjected to hot rolling (S4) with a reduction of about 90% to form a thin plate having a thickness of 2 mm. did. After the oxide scale on the surface of the thin plate is removed again by a grinder (S5), cold rolling (S6) and annealing (S7) for removing the distortion caused by the rolling are repeated by a required number of times to obtain a thickness of 0.1 mm. A substrate 1 of 5 mm was obtained.

Next, the substrate 1 is sized to a predetermined size (50 ×
(100 mm), and both surfaces were subjected to electrolytic plating (S8) to cover an underlayer 2 of Cu or Ni having a thickness of about 3 μm. In addition, Ni is plated first,
The upper surface was further provided with two layers of underlayers 2 and 4 plated with Cu. Next, these intermediate blanks 3 were cold-rolled (S9) at a rolling reduction of about 70% to a thickness of 0.15 mm. Electrolytic plating is further performed on the surface of each of the base layers 2 and 4 of this plate (S10), and Pd having a thickness of about 3 μm is formed.
The terminal blanks 8 and 10 of the present invention covered with the joining surface layer 6 made of the following three types (Cu; Invention Example 1, Ni; Invention Examples 2, Ni and Cu; Invention) Example 3) obtained.
Further, for each invention example, after the cold rolling (S9), diffusion annealing (S11) was performed at about 1000 ° C. for 5 minutes in a vacuum, and electrolytic plating (S12) was applied to each of them to obtain a thickness of about The terminal blanks 8 and 10 covered with the joining surface layer 6 made of 3 μm Pd were also obtained.

On the other hand, as an Fe—Cr alloy, C:
0.028%, Si; 0.34%, Mn; 0.54%,
P: 0.004%, S: 0.005%, Cr: 8.5%,
Rest: vacuum melting of alloy material adjusted to Fe composition
(S1) to form an ingot of a predetermined shape. The ingot was heated to 1100 ° C. and subjected to hot forging (S2) to obtain a thick plate having a thickness of 20 mm and a width of 100 mm. Next, the oxide scale adhering to the surface of this thick plate is removed with a grinder (S
3) After that, it was heated to 1100 ° C. and subjected to hot rolling (S4) with a reduction of about 90% to obtain a thin plate having a thickness of 2 mm. The oxide scale on the surface of this thin plate is removed again by a grinder (S5).
Then, cold rolling (S6) and A for removing internal strain due to the cold rolling (S6)
The substrate 1 having a thickness of 0.5 mm was obtained by repeatedly performing the strain removal annealing (S7) in r gas for a required number of times.

Further, the substrate 1 has a predetermined size (50 ×
(100 mm), and both surfaces were subjected to electrolytic plating (S8) to cover an underlayer 2 of Cu or Ni having a thickness of about 3 μm. In addition, Ni is plated first,
The upper surface was further provided with two layers of underlayers 2 and 4 plated with Cu. Next, these intermediate blanks 3 were cold-rolled (S9) at a rolling reduction of about 70% to a thickness of 0.15 mm. Electrolytic plating is further performed on the surface of each of the base layers 2 and 4 of this plate (S10), and Pd having a thickness of about 3 μm is formed.
The terminal blanks 8 and 10 of the present invention coated with the joining surface layer 6 made of the following three types (Cu; Invention Example 4, Ni; Invention Examples 5, Ni and Cu; Invention) Example 6) obtained.
Further, for each invention example, after the cold rolling (S9), diffusion annealing at about 750 ° C. for 2 minutes is performed in a vacuum (S11), and electrolytic plating (S12) is applied to each of them to obtain a thickness of about 3 mm.
A terminal plate 8 and the like coated with a bonding surface layer 6 of Pd having a thickness of μm were also obtained.

As a comparative example, the same Fe—Ni system as described above,
And a substrate 1 made of an Fe-Cr alloy and prepared by the same process, and plating the underlayers 2 and 4
(S8) and a raw plate for terminal coated with a bonding surface layer 6 made of Pd having a thickness of about 3 μm by performing electrolytic plating (S10) directly on the surface of each substrate 1 without performing cold rolling (S9). Was prepared. The substrate 1 was made of a Fe—Ni alloy, and Comparative Example 1
An Fe-Cr alloy was used as Comparative Example 2. Then, each test piece of each of Invention Examples 1 to 6 and Comparative Examples 1 and 2 was
Sheets were prepared one by one, ten of which were used for the salt spray test and the remaining ten were used for the brazing test.

The salt spray test (JIS-Z2371) was performed as follows. Sprayed over a 24-hour period so that the amount of the sprayed liquid from which the 5% concentration of salt water was collected was 1 to 2 liters per hour on an average of 1 to 2 liters per hour on a horizontal sampling area of 80 cm ² of each test piece. The area of the rust was measured, and this was represented by the area ratio. Invention Examples 1 to 6 and Comparative Examples 1 and 2
Table 1 shows the results of calculating the average value of each of the ten test pieces. In addition, each right column of the invention examples 1-6 shows what performed the electrolytic plating (S12) which obtains a surface layer after performing the said diffusion annealing (S11) about each.

[0019]

[Table 1]

From the results shown in Table 1, it can be seen that the area ratio of rust is much lower in each of the invention examples than in comparative examples 1 and 2, and among the invention examples, the invention examples using the underlayer 2 consisting solely of Cu or Ni. Inventive Examples 3 and 6, in which two underlayers 2, 4 were interposed between the substrate 1 and the bonding surface layer 6 in the order of Ni and Cu, in the order of Ni and Cu, in comparison with 1, 2, 4, and 5, the area of rust was larger. It turns out that the rate is low. Also, in each of the invention examples, it can be seen that the area ratio is slightly lower when the Pd plating (S12) is performed after the diffusion annealing (S11) on the right column side. From these results, in each of the invention examples, the formation of the corrosion battery between the two was significantly reduced by interposing the dense underlayer 2 or 2, 4 between the substrate 1 and the bonding surface layer 6. It is easy to understand what has been done. Further, as in Invention Examples 3 and 6, the two layers of the underlayers 2 and 4 are interposed, and the potential difference between the substrate 1 and the bonding surface layer 6 is more gradually inclined, thereby further improving the corrosion resistance. It is also understood that it becomes easier to obtain. Further, it is understood that the corrosion resistance can be further improved by performing diffusion annealing (S11) between the substrate 1 and the surface layer 6 in advance.

On the other hand, in the brazing test, Sn
-20% Ag was melted, and the test pieces of Invention Examples 1 to 6 and Comparative Examples 1 and 2 were immersed in a molten metal of the brazing material for 10 seconds each for 5 seconds, and the brazing material was wet on each surface. The area that was adhered to the substrate was measured, and this was represented by the area ratio. Table 2 shows the result of calculating the average value for each invention example and comparative example.

[0022]

[Table 2]

From the results shown in Table 2, it can be seen that all of the invention examples have the same or higher wet area ratio as the comparative example. Therefore, the base layer 2 is provided between the substrate 1 and the bonding surface layer 6.
It is easily understood that the interposition of No. 4 does not affect the brazing property at all. Furthermore, when the results of Tables 1 and 2 are combined, each of the base plates of the invention example has excellent corrosion resistance according to the material of the underlayer and the lamination form, and is used as a terminal material in electronic components such as semiconductor elements. However, it is clear that such an electronic component can be easily mounted or joined to a terminal material such as a motherboard on which the electronic component is mounted by brazing.

It should be noted that the present invention is not limited to the above embodiments and examples. As the Fe-Ni-based alloy serving as the substrate, one containing mainly 30 to 50 wt% Ni is used, for example, Fe-36% Ni (Invar), Fe-45% Ni (Permalloy), Fe-32% Ni, etc. Or Cu, C
What added at least 1 type of r, Mo, W, Nb, etc. to 1-4% is used. In addition, Fe-Cr serving as a substrate
As the system alloys, those containing mainly 6 to 18 wt% Cr are used. For example, Fe-13% Cr, Fe-16% Cr, etc., or about 1-3% Ni, etc. are added to these alloys. Is used. Further, the material of the underlayer is also Cu,
In addition to Ni, it is also possible to use alloys thereof, Sn, Au, or Ag, or alloys based on these. Also, the material of the bonding surface layer is Pd in addition to Pd.
A base alloy, a metal belonging to the platinum group consisting of Pt, Ru, Os, Rh, and Ir, and an alloy based on these metals can also be used.

Further, the underlayer and the bonding surface layer may be coated on only one surface of the substrate, or may be used, for example, as a lead frame, depending on the bonding form with the terminal material to be brazed. It is also possible to cover only a part of one or both surfaces of the substrate, for example, to cover only the surface of the part which becomes the outer lead after being punched by a press. In addition, it is also possible to use the terminal plate for an external terminal material in an electronic component such as a diode, a capacitor, or a resistive chip, or a terminal material including the internal terminal portion, in addition to the lead frame. is there.

[0026]

According to the terminal blank of the present invention described above, the bonding of Pd or the like to the surface of a substrate made of an Fe-Ni or Fe-Cr alloy through an underlayer made of Cu or the like. Since the surface layer is coated with the surface layer for use, it is possible to provide a terminal material having excellent corrosion resistance in which formation of a corrosion cell between the surface layer and the substrate is significantly suppressed. In addition, according to the method for manufacturing a terminal element plate of the present invention, the terminal element sheet in which the bonding surface layer is coated on the substrate via the dense base layer with a dense structure is reliably and in accordance with a required amount. It can be easily provided.

[Brief description of the drawings]

1 (A) and 1 (B) are schematic flow charts showing a production method of the present invention.

FIGS. 2A to 2C are cross-sectional views showing respective steps of one manufacturing method of the present invention, and FIGS. 2D and 2E are cross-sectional views showing respective steps of another manufacturing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Board | substrate 2, 4 ... Underlayer 3 ... Intermediate base plate 6 ... Bonding surface layer 8, 10 ... Terminal Base plate

[Table 1]

[Table 2]

Claims (5)

[Claims] 1. A substrate made of an Fe--Ni-based or Fe--Cr-based alloy, and at least one surface of the substrate
A bonding surface layer made of a metal belonging to the platinum group, such as Pd, or an alloy based on these metals is coated via an underlayer made of at least one of u, Ni, Sn, Au, and Ag. A terminal plate for a terminal. 2. The thickness of the underlayer is at least 0.3 μm.
2. The terminal plate according to claim 1, wherein: 3. The bonding surface layer has a thickness of at least 0.5.
3. The terminal plate according to claim 1, wherein the terminal plate has a thickness of 03 μm or more. 4. 4. A substrate made of an Fe—Ni-based or Fe—Cr-based alloy, wherein Cu, Ni, S
An underlayer consisting of at least one of n, Au, and Ag is coated by plating, and the obtained intermediate base plate is subjected to cold rolling at a rolling reduction of 5% or more, and then the surface of the underlayer is coated. Plating a metal belonging to the platinum group such as Pd or an alloy based on these metals to cover the joining surface layer. 5. The method according to claim 4, wherein after the cold rolling, diffusion annealing is further performed in a vacuum or an inert gas.