JPS60152646A - Material for lead frame for semiconductor - Google Patents

Abstract

PURPOSE:To obtain the titled material having mechanical properties and heat resistance close to those of an iron-base material as well as superior electric conductivity by adding prescribed percentages of Fe, P, Ni and Sn to Cu. CONSTITUTION:This material for a lead frame for a semiconductor consists of, by weight, 0.05-0.15% Fe, 0.025-0.050% P, 0.002-0.20% Ni, 1.0-5.0% Sn and the balance Cu or further contains <=0.50% in total of 0.002-0.010% Mg and/or 0.002-0.50% Zn and/or <=0.05% in total of one or more among 0.002-0.05% each of Mn, Si and Al. The material has superior strength, repeated bendability and stiffness without deteriorating electric conductivity peculiar to a Cu alloy, and when the material is tinned, it has a superior wetting property to solder.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to lead frame materials for semiconductors such as TCs and LSIs, and more specifically, to lead frames for semiconductors that have excellent repeated bendability, stiffness strength, and solder wettability of tin-plated materials. It is related to materials.

Conventionally, iron-based materials such as Kovar and iron-nickel have been mainly used as lead frame materials for ICs, LSTs, etc., and copper-based materials have been used for transistor lead frames, etc. As pure copper and low tin copper, Cu-0,1u+t%Fe-0,03u+t%
There are copper alloys that are almost pure copper, such as P.

However, compared to iron-based materials such as Kovar and iron-nickel, these copper-based materials are inferior in repeated bendability and stiffness strength required for lead frames for semiconductors, so they are used as lead frames for ICs, LSIs, etc. cannot withstand use.

However, in recent years, as ICs and LSIs have rapidly become smaller, more densely packed, and have higher output, demands for increased pin count and improved heat dissipation have increased, and mechanical properties similar to those of iron-based materials have been developed. The development of a lead frame material for semiconductors made of a copper alloy that has heat resistance and excellent conductivity is currently in great demand.

As explained above, in view of the problems of conventional copper-based materials as lead frame materials for semiconductors and the demand for copper-based materials as preferred lead frame materials for semiconductors, the present inventor has conducted intensive research and found that copper or Lead frame materials for semiconductors such as ICs and LSIs made of copper alloys that have excellent strength, repeated bendability, and stiffness strength without impairing the inherent conductivity of copper alloys, as well as excellent solder wettability for tin-plated materials. It was developed.

The semiconductor lead frame material according to the present invention includes (1) Fe
O, 05-0,], 5u+t%, P 09025-0
．． 050u+t%, Ni 0.002-0.20wt
%, Sn 1,0-5.0+ut%, the balance being essentially Cu, (2) Fe O,05-0,1
5wt%, PO,025-0,050u+L%, N
i O,002-0,20u+t%, Sn 1,0-5
．． Ou+L%, -3=, and further includes MgO,002-0,0]Ou+L%, ZnO,0
02-0,50u+t%, one or two types in total 0
, 50wt% or less, and the remainder is essentially Cu, (3) FeO,05-0,15u+t%, P
O,025-0,050u+t%, Ni Q, QO2-
0.20wt%, Sn 1.0-5.0wt%,
Furthermore, Mn 0.002-0.05nt%, SiO,002
-0.05u+t%, AI 0.002-0.05u
One or more types selected from +L% for a total of 0
,0005-0.05u+t% or less, and the remainder is essentially Cu, (4) Fe 0005-0.15u+t%, P
Q, 025-0.050wt%, N i O, 002
-0.20wt%, Sn 1.0-5.0wt%, and further contains Ml? 0.002-0.010wt%, ZnO,0
02-0.50u+L% of one or two types in total of 0.
Contains 50u+t% or less, and Mn 00002 to 0.05111t%, Si 0.0
02~0.05u+t%4- A1 1 selected from 0.002~0.05iut%
Contains a total of 0.05...t% or less of a species or two or more species,
This invention consists of four inventions, with the fourth invention being a semiconductor lead frame material characterized in that the remainder is essentially Cu.

The semiconductor lead frame material according to the present invention will be described in detail below.

First, the components and component ratios in the semiconductor lead frame material according to the present invention will be explained.

Fe is an element that forms iron phosphide to improve strength, repeated bendability, and stiffness strength, and when the content is 0.
If it is less than 0.05 wt%, P (content 0.025 to 0.050
Even if it combines with O (u+t%) to form iron phosphide, no effect of improving strength can be expected, and if the content exceeds O, 15IIlt%, solid solution iron that cannot form iron phosphide increases. As a result, conductivity decreases. Therefore, the Fe content is set to 0.05-0.15u+t%.

P is an element that forms iron phosphide to improve strength, repeated bendability, and stiffness strength, and the content is 0.0
If the content is less than 25u+L%, iron phosphide will not be formed to the extent that it can contribute to strength improvement, and if the content exceeds 0.050u+1%, a low melting point eutectic of Cu and Cu3P will occur, making it impossible to obtain a healthy ingot. It disappears. Therefore, the P content is 0.0
25 to 0.050 t%.

N1 is an element that improves strength, repeated bendability, and stiffness strength when dissolved in solid solution, and also has the important effect of preventing deterioration of solder wettability of tin-plated materials. If it is less than 0,002u+t%, the effect of suppressing the deterioration of the solder wettability of the tin-plated material is small, and
The higher the content, the more effective it is to suppress the deterioration of the solder wettability of the tin-plated material, but if the content exceeds 0.20u+t%, the conductivity will decrease. Therefore, the Ni content is 0.
002 to 0.20+ut%.

Sn is an element that improves strength, repeated bendability and stiffness strength by solid solution, and the content is ], 0iu1
If it is less than 5.%, such an effect will be small. Ou+
If the content exceeds J%, hot workability deteriorates, making it difficult to commercialize the product and further leading to an increase in cost. Therefore, the Sn content is set to 1.0 to 5.0 IIlt%.

Mg is an element that forms a Mg5P2 compound with P, improves the tenacity strength, and deoxidizes and desulfurizes the molten metal. If the content is less than 0.0O2ILIL%, this effect will not occur, and if the content is less than 0.010ult% If the content exceeds this amount, the molten metal will oxidize and a healthy ingot will not be obtained.

Therefore, the Mg content is 0.002-0.010u+t%
shall be.

Zn is an element that degasses the molten metal, and the content is 0.0
This effect is absent at less than 0.02u+t%, and 0.50
If the content exceeds L%, solder wettability will deteriorate. Therefore, the Zn content is 0.002 to 0.50
111t%.

In addition, when containing two types of Mg and Zn at the same time, if the total content exceeds 0.50 LIIL%, the molten metal will oxidize or the solder wettability will deteriorate. The total content of the two types is 0.50u+t
% or less.

Mn, Si, and AI are elements that deoxidize the molten metal, and if the content of any element is less than 0.002u+t%, there is no effect, and if the content exceeds 0.05iuL%, Solder wettability deteriorates. Therefore, Mn content 1
10.002-0.05wt%, Si content! i0.
002-0.054L%, A1 content is 0.002-0
．． 05u+t%.

In addition, if two or more of Mn, Sl, and A1 are contained, the solder wettability will deteriorate if the total content exceeds 0.05u+t%, so select one from among Mn, Si, and AI. If it contains two or more types, the total amount is 0.05u+
L% or less.

In addition, Cr, Ti, Zr, etc. can be contained, and these elements have the effect of refining the crystal grains of the ingot and improve the repeat bendability and stiffness strength. If the content is less than 0.002u+t%, this effect will not occur, and if the content exceeds 0.031%, the solder wettability of the tin-plated material will decrease, and the molten metal will be more likely to be oxidized. Therefore, the content of Cr, Ti, and Zc is 0.002~
It is set to 0.03u+t%. Furthermore, B can be contained.B has a cleaning effect on the metal base material and improves solder wettability, but if the content is less than 0.002u+t%, this effect is small, and =8-0. If the content exceeds 03u+t%, Cu and the intermetallic compound CuB22 will precipitate, and if noble metal plating such as gold or silver is applied, it will easily become 7 Cr. Therefore, the B content is 0.00
2-0.03u+t%.

Next, examples of semiconductor lead frame materials according to the present invention will be described.

EXAMPLES Samples were prepared by processing lead frame materials for semiconductors made of copper alloys having the components and proportions shown in Table 1, respectively, through the steps described below.

Using electrolytic copper as a raw material, a copper alloy with the ingredients and proportions shown in Table 1 is melted in a Kryptor furnace under charcoal coating,
60mmtX 60 in cast iron Bunku mold
After casting an ingot of m1nWX 200 mmL, the front and back sides of the ingot were cast at 800°, 2.5 mm in front and back.
After hot rolling to a thickness of 15+nmt at a temperature of 600
Rapid cooling from a temperature of ℃ or above, descaling with acid, and then cold rolling to 0.33-0, 74m+n
Samples Nos. 1 to 8 according to the present invention shown in Table 2 were rolled to a thickness of 25 mm, subjected to intermediate annealing at 500° C. for 1 hour, and then cold-opened to a thickness of 25 mm. A semiconductor lead frame material and a comparative material of sample No. 10.12 were prepared.

In addition, as comparative material No. 9.11, a commercially available material was used.

Test pieces balanced in the rolling direction were prepared from these samples.

Table 2 shows the test results for lead frame materials for semiconductors.

The test method is as follows.

(1) The tensile test piece was a JTS No. 13 B test piece 1), and the electrical conductivity was measured according to JIS 1-0505.

(2) The repeated bending test was conducted with an internal lead width of 1.
5111m, external lead width 0.50mm I
After making the lead for C by punching, attach a 23mm mark to one end of the lead.
Attach a weight of 08 and perform one-way reciprocating bending.
The number of times it took to break was measured. In this case, the number of samples is 10 and the average value is shown.

(3) Stiffness strength is 0, 25 mmtX I
Grasp one end of the test piece of Q +nmW×L and press the grip part.
) A load was applied at a distance of 40 mm using a knife jig, and the strength was measured when forming an angle of 10' from the initial state.

(4) The solder wettability of the tin-plated material is determined by directly applying silver plating to a thickness of 8 μm and then holding it at IHr in water vapor for 5 to 1
After immersing in the flux for 0 seconds, it was placed in a solder bath of 60u+t%5n-40iut%PI) at 260℃=11-.
Solder wettability after second immersion was evaluated.

◎...95% or more, ○...91~94%, △...50~
90%, ×...50% or less, of which O and ◎ are passed.

12- As is clear from this Table 2, Nos. 1 to 8 of the lead frame materials for semiconductors according to the present invention are different from the comparative materials N.
It can be seen that it has overall superior performance compared to No. o, 9 to No. 12.

In other words, Comparative material No. 9 has good conductivity, but has poor repeat bendability and solder wettability of the tin-plated material, and has poor conductivity.
Comparison material No. 1 with inferior strength.

No. 10 is a tin-plated material with good solder wettability and electrical conductivity, but has poor repeated bending properties and poor tensile strength and elongation. Comparison material No. 11 has poor repeated bending properties and tensile strength. Although it is good, the solder wettability of the tin-plated material is extremely poor, and the conductivity and elongation are also very poor. Comparative material No. 1
Sample No. 2 has good repeated bendability, but is poor in tin plating solder wettability and stiffness strength, and has poor electrical conductivity.

In addition, No. of the semiconductor lead frame material according to the present invention,
Since No. 4 contains Zn and Mg, it has improved repeated bendability and stiffness strength compared to No. 1.
, 6 contains Mn and Si, and No. 8 contains Si and A1, so it has better repeat bendability and stiffness strength than No. 1, and No. 5 contains Zn. ,M
g, No. 7 contains Mn and AI, so comparative materials No. 1.2 and No. 11 to No. 4, No. 6,
It is superior in repeated bending property and stiffness strength compared to No. 8. This means that M[? ,7. n, M
This proves that the inclusion of Il, Si, and AI improves the bendability and stiffness strength.

As explained above, the semiconductor lead frame material according to the present invention has the above structure.
It is also a material that has excellent repeated bending properties, stiffness strength, and solder wettability for tin-plated materials as a lead frame material for LSI and the like.

Claims (4)

[Claims] (1) FeO, 05-0, 15wt%, P 0.02
5-0.050Illt%,NiO,0020,2
(A lead frame material for semiconductors characterized by containing 1.0 to 5.0 wt% of Sn and 1.0 to 5.0 wt% of Sn, with the remainder being essentially Cu. (2) Fe O,050,15u+t%, P O,02
5-0,05011 It%, N i O, 002-0,
20u+t%, Sn 1.0-5.0iuL%, further contains Mg 0.002-0.010ult,%, ZnO10
A lead frame material for a semiconductor, comprising a total of 0.50 wt % or less of one or two of the following: 0.02 to 0.50111 t %, and the remainder being essentially Cu. (3) FeO, 05-0, 15u+t%, P 000
25-0.050u+t%, Ni 0.002-0.
20u+t%, Sn 1.0-5.0wt%, and further contains Mn 000020,05u+t%, Si 0.00
2-0.05u+t%, AI 0.002-0.05...
A total of one or two or more types selected from t% is 0.
A lead frame material for a semiconductor, characterized in that it contains 05u+L% or less, and the remainder is essentially Cu. (4) FeO605-0,15wt%, PO,025
-0,050...L%, Ni O,002-0,20wt
%, Sn 1.0-5. Contains Ou+t%, and further contains Mg 0.002-0.010u+t%, Zll 0,
002-0.50u+L% one or two types in total 0
．． Contains 50111t% or less, and Mn 0.002-0.05u+t%, Si 0.00
2-0.05wt%A10.002~0.05u+t%
A total of 0.05 for one or more of the following
A lead frame material for a semiconductor, characterized in that it contains u+t% or less, and the remainder is essentially Cu.