TWI688129B - Aluminum alloy lead frame and manufacturing method thereof - Google Patents

Abstract

The invention provides an aluminum alloy lead frame and a manufacturing method thereof. The lead frame provides an aluminum alloy substrate having opposite upper and lower surfaces; wherein, a reflective composite layer is disposed on the upper surface, and the reflective composite layer The sequence includes a first intermediate layer, a functional layer, and a reflective layer, the first intermediate layer is disposed between the aluminum alloy substrate and the functional layer; and a welded composite layer is disposed on the lower surface, the welded composite layer includes sequentially A second intermediate layer, a welding layer, and a second protective layer. The second intermediate layer is disposed between the aluminum alloy substrate and the welding layer to obtain an aluminum alloy lead frame. The invention improves the problems of poor adhesion of the film layers of the general aluminum alloy substrate and the poor reflectivity of the existing copper alloy lead frame by improving the bonding force of the functional layer and the welding layer with the aluminum alloy substrate, not only improves Its application value, in turn, provides a lead frame with advantages in price and weight.

Description

Aluminum alloy lead frame and manufacturing method thereof

The invention relates to a lead frame, especially an aluminum alloy lead frame.

Light Emitting Diode (LED: Light Emitting Diode) as the light source of light source, its high brightness, low energy consumption, small size, long life, and stable performance characteristics, making it extensive and rapid development. When the die is stuck on the lead frame to form various types of LEDs, the lead frame shoulders the requirements of high light extraction performance, better conductivity and thermal conductivity; the copper alloy lead frames commonly used in the market have the characteristics of good thermal conductivity and good conductivity. Furthermore, a metal layer with a reflective function is provided on the surface of the copper alloy lead frame, which can effectively extract the light source emitted from the LED element. For example, the copper alloy lead frame for LED of the Republic of China Invention Patent No. I564406 and its manufacturing method, that is, using copper alloy as the lead frame substrate, by improving the thermal conductivity, electrical conductivity and surface roughness of the copper alloy substrate, and A reflective layer of silver layer is formed on the surface to improve the light extraction efficiency of the LED element.

However, the price of raw materials of copper alloys is high, and with today's electronic products requiring light, thin and short characteristics, it is always the direction of the industry to use different materials to manufacture lead frames with the same or better performance.

Aluminum alloy not only has a price advantage over copper alloy, but also has a lower aluminum density (2.7g/cm ³ ) than copper density (8.9g/cm ³ ). Using aluminum alloy can achieve the purpose of reducing weight; in particular, the surface of aluminum alloy The roughness is better than copper alloy, which can produce a reflective layer with better reflectivity.

However, aluminum has a strong affinity for oxygen, and an oxide film is easily formed on the surface to weaken the binding force between the reflective layer and aluminum. Aluminum is an amphoteric metal with high chemical activity. Corrosion of the aluminum surface caused by pretreatment of the coating will reduce the bonding force of the coating; The coating film of the reflective function is peeled off, the welding layer is separated, or the welding wire is dropped, so the base material of the lead frame is still mostly copper and its alloy.

In view of the above technical defects of the existing aluminum alloy lead frame, the object of the present invention is to provide an aluminum alloy lead frame with good film adhesion and reflectivity, and its price and weight have advantages.

In order to achieve the foregoing object, the present invention provides an aluminum alloy lead frame which provides an aluminum alloy substrate having an upper surface and a lower surface opposite to each other; wherein, a reflective composite layer is provided on the upper surface, the reflection The composite layer includes a first intermediate layer, a functional layer and a reflective layer in sequence, the first intermediate layer is disposed between the aluminum alloy substrate and the functional layer; and a welding composite layer is disposed on the lower surface, the welding The composite layer includes a second intermediate layer, a welding layer, and a second protective layer in sequence. The second intermediate layer is disposed between the aluminum alloy substrate and the welding layer.

By the above-mentioned technical means, the aluminum alloy lead frame of the present invention uses an aluminum alloy as a substrate, its surface roughness is good to improve reflectivity, and its thermal conductivity is good to avoid the occurrence of heat peaks; in addition, a reflective composite is provided on the aluminum alloy substrate Layer and welding composite layer, and control the material and thickness of the first intermediate layer, functional layer, reflective layer, second intermediate layer, welding layer and second protective layer; wherein, the first intermediate layer and the second intermediate layer can Enhances the adhesion of the film layer formed thereon, and can reduce the peeling phenomenon caused by the thermal energy generated by the surface-mounted device (SMD); furthermore, the functional layer provided on the first intermediate layer It can make the reflective layer adhere well and improve the solderability of subsequent welding; the reflective layer has good adhesion, can highlight the low roughness of the aluminum alloy surface, improve the reflectivity, and then effectively extract the light source emitted from the LED element. Therefore, the above technical means not only improve the adhesion between the film layers on the aluminum alloy substrate, but also provide an aluminum alloy lead frame with higher reflectivity compared to the existing copper alloy lead frame, thereby enhancing the application of the aluminum alloy lead frame value.

According to the present invention, a first protective layer can be further provided on the reflective layer of the reflective composite layer, the first protective layer can maintain the film quality of the reflective layer, and thus the reflective layer can maintain its optimal reflectivity .

The present invention also provides a method for manufacturing an aluminum alloy lead frame, which includes the following steps: preparing an aluminum alloy substrate having an upper surface and a lower surface opposite to each other; a first order is provided on the upper surface of the aluminum alloy substrate in sequence An intermediate layer, a functional layer and a reflective layer, whereby a reflective composite layer is formed on the upper surface of the aluminum alloy substrate, the reflective composite layer includes the first intermediate layer, the functional layer and the reflective layer in sequence An intermediate layer is disposed between the aluminum alloy substrate and the functional layer; and a second intermediate layer, a soldering layer, and a second protective layer are sequentially disposed on the lower surface of the aluminum alloy substrate, thereby the aluminum alloy A welding composite layer is formed on the lower surface of the substrate, the welding composite layer includes the second intermediate layer, the welding layer and the second protective layer in sequence, the second intermediate layer is disposed between the aluminum alloy substrate and the welding layer To form the aluminum alloy lead frame.

According to the manufacturing method of the aluminum alloy lead frame of the present invention, the reflective composite layer further includes a first protective layer, and the first protective layer is disposed on the reflective layer.

According to the present invention, the aluminum alloy substrate used for the aluminum alloy lead frame may be a forged aluminum alloy, preferably, the purity of the forged aluminum alloy is higher than 99.0%, including aluminum alloy or aluminum magnesium alloy; the present invention is applicable Aluminum alloy substrate materials, such as forged aluminum alloy 1000, 3000 or 5000 series, but not limited to this; the thickness of the aluminum alloy substrate is between 0.1 millimeters (mm) to 1.5mm, preferably, the thickness is between 0.2mm to 0.8mm.

According to the present invention, the reflective composite layer and the welding composite layer are respectively provided with the first intermediate layer and the second intermediate layer. The first intermediate layer and the second intermediate layer may be made of the same or different materials. The material of the second intermediate layer may include aluminum, titanium, chromium, nickel, their metal alloys, their oxides, their nitrides, their nitrogen oxides, or a combination thereof, but not It is only limited to this; the first intermediate layer and the second intermediate layer applicable to the present invention may be, for example, a titanium metal layer, a titanium oxide layer, an aluminum-titanium alloy layer, or an aluminum titanium nitride layer, but it is not limited thereto.

According to the present invention, the thickness of the first intermediate layer and the second intermediate layer is between 2 nanometers (nm) and 1000 nm, preferably, the thickness is between 2 nm and 200 nm.

According to the present invention, the first intermediate layer and the second intermediate layer may use technical means including electroplating, vacuum coating technology, etc., but it is not limited to this. Among them, the vacuum coating technology has the characteristics of strong binding force between the film layer and the workpiece surface, fast film deposition rate, wide variety of coatable layers, and stable film performance; for example, using vacuum coating technology to attach titanium metal to an aluminum substrate The surface serves as a coating material for the first intermediate layer or the second intermediate layer, which can improve the adhesion of the film layer formed on the first intermediate layer and the second intermediate layer.

According to the present invention, the material of the functional layer includes a metal or a metal alloy, preferably a copper layer; the thickness of the functional layer is between 2 nm and 2500 nm, preferably, the thickness is between 100 nm and 1000 nm.

According to the present invention, the material of the reflective layer includes a metal or a metal alloy. Preferably, the reflective layer may be a silver layer or an aluminum layer. The thickness of the reflective layer is between 50 nm and 6000 nm, preferably, the thickness is between 100 nm and 4000 nm.

According to the present invention, the material of the first protective layer includes a non-metallic low absorption material. Preferably, the first protective layer may be a silicon oxide layer. The thickness of the protective layer is between 0.5 nm and 20 nm, preferably, the thickness is between 0.5 nm and 10 nm.

According to the present invention, the material of the soldering layer may include metals or metal alloys. Preferably, the soldering layer may be a copper layer. The thickness of the welding layer is between 100 nm and 5000 nm, preferably, the thickness is between 500 nm and 1000 nm; and the surface of the aluminum alloy substrate coated with the welding layer has no more than 1.2×10 ^-1 ohm at 25°C. The resistivity of square millimeter/meter (Ω mm ² /m).

According to the present invention, the material of the second protective layer includes a metal or a metal alloy. Preferably, the second protective layer may be a silver layer. The thickness of the protective layer is between 50 nm and 1000 nm, preferably, the thickness is between 50 nm and 200 nm.

According to the present invention, the lead frame can be applied not only to the products of diodes and light-emitting diodes, but also to integrated circuits, such as semiconductors, as connecting elements for chips and printed circuit board circuits, but it is not limited to this .

Therefore, the present invention improves the adhesion between the film layers of the aluminum alloy lead frame, and provides an aluminum alloy lead frame with better reflectivity than the existing copper alloy lead frame, which effectively reduces the product price, reduces the weight, and further Improve the application value of the aluminum alloy lead frame.

1. 1’, 1”: Aluminum alloy lead frame

2: copper alloy lead frame

11, 11’: upper surface

21: Reflective composite layer

L1: Aluminum alloy substrate

L1’: Copper alloy substrate

12, 12’: Lower surface

22: Welding composite layer

L2: the first middle layer

L3, L3’: functional layer

L4, L4’: reflective layer

L5: the first protective layer

L6: Second middle layer

L7: Welding layer

L8: second protective layer

1 is a cross-sectional view of the aluminum alloy lead frame of Example 1. FIG.

2 is a cross-sectional view of the aluminum alloy lead frame of Example 2. FIG.

3 is a cross-sectional view of the copper alloy lead frame of Comparative Example 1. FIG.

4 is a cross-sectional view of the aluminum alloy lead frame of Comparative Example 2. FIG.

Several examples and comparative examples are listed below to illustrate the implementation of the present invention. Those skilled in the art can easily understand the advantages and effects achieved by the present invention through the contents of this specification, and proceed without departing from the spirit of the present invention. Various modifications and changes to implement or apply the content of the present invention.

Example 1: Aluminum alloy lead frame

As shown in FIG. 1, the aluminum alloy lead frame of Example 1 is manufactured by the following method. First, the 5005 series of aluminum-magnesium alloy is selected as the aluminum alloy substrate L1, which has a thickness of 0.3mm; the substrate can be in the form of a roll material, which is manufactured in a continuous process. The first intermediate layer L2 is formed on the upper surface 11 of the aluminum alloy substrate L1 by vacuum coating technology. The first intermediate layer L2 is a titanium metal layer with a thickness of 20 nm; then, the first intermediate layer L2 is formed by vacuum coating technology A functional layer L3 is formed thereon. The functional layer L3 is a copper layer with a thickness of 800 nm. Then, a second intermediate layer L6 is formed on the lower surface 12 of the aluminum alloy substrate L1 by vacuum coating technology, and the second intermediate layer L6 is a titanium metal layer , Its thickness is 20nm; next, vacuum coating Technology, a solder layer L7 is formed on the second intermediate layer L6, the solder layer L7 is a copper layer, and its thickness is 800 nm; another plating layer is used to form a reflective layer L4 on the functional layer L3, and the reflective layer L4 is a silver layer, and its thickness is 2000 nm Finally, a second protective layer L8 is formed on the solder layer L7 by electroplating. The second protective layer L8 is a silver layer with a thickness of 1000 nm. The aluminum alloy substrate after the coating is formed by stamping to obtain an aluminum alloy lead frame 1.

As shown in FIG. 1, the aluminum alloy lead frame 1 has an aluminum alloy substrate L1, a reflective composite layer 21 and a welding composite layer 22. The aluminum alloy substrate L1 has an upper surface 11 and a lower surface 12 opposite to each other. The reflective composite layer 21 is disposed on the upper surface 11, the reflective composite layer 21 includes a first intermediate layer L2, a functional layer L3, and a reflective layer L4; and the lower surface 12 is provided with a welding composite layer 22, the welding composite layer 22 has a Two intermediate layers L6, welding layer L7 and second protective layer L8.

Example 2: Aluminum alloy lead frame

As shown in FIG. 2, the manufacturing process of the aluminum alloy lead frame of Example 2 is made by using the vacuum coating technology throughout the following method. First, the 1085 series aluminum alloy is selected as the aluminum alloy substrate L1, and its thickness is 0.2 mm; the base material can be in the form of a roll material and manufactured in a continuous process. A first intermediate layer L2 is formed on the upper surface 11 of the aluminum alloy substrate L1. The first intermediate layer L2 is a titanium oxide layer (TiO _x ) with a thickness of 10 nm; then, a functional layer L3 is formed on the first intermediate layer L2 , The functional layer L3 is a copper layer with a thickness of 800 nm; and a reflective layer L4 is formed on the functional layer L3, the reflective layer L4 is a silver layer with a thickness of 1000 nm; and then a first protective layer L5 is formed on the reflective layer L4, the first The protective layer L5 is a silicon oxide layer (SiO _x ) with a thickness of 10 nm; next, a second intermediate layer L6 is formed on the lower surface 12 of the aluminum alloy substrate L1, and the second intermediate layer L6 is a titanium oxide layer (TiO _x ) with a thickness of 10 nm; a solder layer L7 is formed on the second intermediate layer L6, and the solder layer L7 is a copper layer with a thickness of 400 nm; and finally, a second protective layer L8 is formed on the solder layer L7, the second protection Layer L8 is a silver layer with a thickness of 500 nm. After the coating, the aluminum alloy substrate is formed by stamping to obtain an aluminum alloy lead frame 1'.

As shown in FIG. 2, the aluminum alloy lead frame 1'has an aluminum alloy substrate L1, a reflective composite layer 21 and a welding composite layer 22. The aluminum alloy substrate L1 has an upper surface 11 and a lower surface 12 opposite to each other. The The reflective composite layer 21 is disposed on the upper surface 11. The reflective composite layer 21 includes a first intermediate layer L2, a functional layer L3 and a reflective layer L4, and a first protective layer L5; and the lower surface 12 is provided with a welding composite layer 22, which The welding composite layer 22 has a second intermediate layer L6, a welding layer L7, and a second protective layer L8.

Comparative Example 1: Copper alloy lead frame

In addition, in order to facilitate the comparison of the difference in adhesion and reflectivity between the lead frames of other materials and the aluminum alloy lead frames of the above examples 1 and 2, a copper alloy lead frame 2 is also prepared in the present invention, as shown in FIG. 3, Comparative Example 1 The copper alloy lead frame is made by the following method. First, the copper alloy substrate L1' is selected and its thickness is 0.2mm; a functional layer L3' is formed on the upper surface 11' of the copper alloy substrate L1' by electroplating, and the functional layer L3' is a copper layer with a thickness of 100nm to 200nm Next, a reflective layer L4' is formed on the functional layer L3' by electroplating, the reflective layer L4' is a silver layer, and its thickness is 2500 nm. The coated copper alloy substrate is formed by stamping and processing to obtain a copper alloy lead frame 2.

As shown in FIG. 3, the copper alloy lead frame 2 has a copper alloy substrate L1' having opposed upper and lower surfaces 11' and 12' on the copper alloy substrate L1'. The upper surface 11' is provided with a functional layer L3' and a reflective layer L4'.

Comparative Example 2: Aluminum alloy lead frame without first intermediate layer

In addition, in order to facilitate comparison of the difference in adhesion between the lead frame without the first intermediate layer and the aluminum alloy lead frame of the above examples 1 and 2, an aluminum alloy lead frame 1" is prepared in the present invention. As shown in FIG. 4, the comparative example The aluminum alloy lead frame of 2 is made by the following method: First, the aluminum alloy substrate L1 is selected, which has a thickness of 0.2 mm, and a functional layer L3 is formed on the upper surface 11 of the aluminum alloy substrate L1 by vacuum coating technology, and the functional layer L3 is The thickness of the copper layer is 1000 nm; then, a reflective layer L4 is formed on the functional layer L3 by electroplating, and the reflective layer L4 is a silver layer with a thickness of 2000 nm. The aluminum alloy substrate after the coating is formed by stamping to obtain an aluminum alloy Lead frame 1".

As shown in FIG. 4, the aluminum alloy lead frame 1" has an aluminum alloy substrate L1, and the aluminum alloy substrate L1 has an upper surface 11 and a lower surface 12 opposite to each other. The upper surface 11 is provided with a functional layer L3 and a reflective layer L4.

Test example: Characteristic analysis of lead frame

This test example analyzes the adhesion of the aluminum alloy lead frame test pieces of Examples 1 and 2 and the copper alloy lead frame test piece of Comparative Example 1 and the aluminum alloy lead frame test piece of Comparative Example 2 by the same test method as described below Sex test and total reflectance test.

experiment method:

1. Adhesion test: The test sample selected in this test example was tested on the alloy substrate (hereinafter referred to as the lead frame test piece) which had not been stamped but the film layer had been plated before the above examples and comparative examples. Bake 210 (mm) × 297 (mm) A4 size lead frame test pieces at 180°C for 1 hour and 4 hours respectively. After the lead frame test pieces are cooled to room temperature, use Japanese Michiban tape (Nichiban) for attachment Performance test; stick the tape to the film layer on the surface of the lead frame test piece, quickly pull the tape at a 45-degree angle, and observe whether there is a peeling condition between the film layer and the substrate of the sample after the tape is stuck to the film; if The strip of the conductive frame has a stripping of more than 1.0mm, or the stripping of the strip of the conductive frame from 0.3mm to 1.0mm is more than 7, indicating that the adhesion of the coating of the aluminum alloy is not good, and the film adhesion is judged Poor, expressed as "NG" in Table 1 below; if the stripping condition of the lead frame test strip after sticking and tearing the film is less than 0.3mm, or the stripping condition of the conductive frame test strip from 0.3mm to 1.0mm is 7 Below the limit, it is judged that the adhesion of the film layer is good, which is indicated as "OK" in Table 1 below.

2. Total reflectance test: According to the measurement method specified in DIN 5036 part 3, the lead frame test piece is placed in the measurement port of the reflection/transmittance measuring instrument (model: LMT RT-500), and the visible range of the light source The total reflectance is measured between 380nm and 780nm; the higher the total reflectance value, the better the reflectivity of the reflective layer of the lead frame test piece.

Table 1: Analysis results of the characteristics of the lead frame test pieces of Examples 1 and 2 and Comparative Examples 1 and 2.

As shown in Table 1 above, comparing the results of the adhesion test, the aluminum alloy lead frames of Examples 1 and 2 with the first intermediate layer were compared with the aluminum alloy lead frames without the first intermediate layer of Comparative Example 2, Examples 1, 2 The adhesion test of the aluminum alloy lead frame is good, and the test result of the aluminum alloy lead frame without the first intermediate layer of Comparative Example 2 is NG; it means that the first intermediate layer is applied to the aluminum alloy lead frame of Examples 1 and 2 It can effectively improve the adhesion between the aluminum alloy substrate and each film layer.

The total reflectivity test results of the aluminum alloy lead frames of Examples 1 and 2 are compared with the total reflectivity test results of the copper alloy lead frames of Comparative Example 1, and the total reflectivity of the aluminum alloy lead frames of Examples 1 and 2 are both Up to 97%, higher than the total reflectivity of the copper alloy lead frame of Comparative Example 1; it means that if the aluminum alloy lead frames of Examples 1 and 2 are applied to the light-emitting diode, they can have higher reflectivity , To achieve better light extraction efficiency.

Conductivity: The resistivity of the aluminum alloy substrate selected in Examples 1 and 2 does not exceed 1.2×10 ^-1 Ω mm ² /m at 25°C.

Based on the above analysis results, it can be seen that the technical means of the present invention can effectively improve the adhesion between the various layers of the aluminum alloy lead frame, and the aluminum alloy lead frame has good reflectivity, and reduces the production cost and weight of the lead frame. Enhance the application value of the present invention.

Claims (12)

An aluminum alloy lead frame includes: an aluminum alloy substrate having an upper surface and a lower surface opposite to each other; and a reflective composite layer disposed on the upper surface, the reflective composite layer sequentially including a first intermediate layer , A functional layer and a reflective layer, the first intermediate layer is disposed between the aluminum alloy substrate and the functional layer; and a welded composite layer is disposed on the lower surface, the welded composite layer is sequentially disposed including a first Two intermediate layers, a welding layer and a second protective layer, the second intermediate layer is disposed between the aluminum alloy substrate and the welding layer; wherein, the material of the first intermediate layer and the second intermediate layer includes aluminum, Titanium, chromium, nickel or their metal alloys, their oxides, their nitrides, or their nitrogen oxides. The aluminum alloy lead frame according to claim 1, wherein the reflective composite layer further includes a first protective layer, and the first protective layer is disposed on the reflective layer. The aluminum alloy lead frame according to claim 1, wherein the thickness of the aluminum alloy substrate is between 0.1 mm and 1.5 mm. The aluminum alloy lead frame of claim 3, wherein the first intermediate layer and the second intermediate layer are a titanium metal layer, a titanium oxide layer, an aluminum titanium alloy layer, or an aluminum titanium nitride layer. The aluminum alloy lead frame according to claim 1, wherein the material of the functional layer includes metal or metal alloy; the material of the reflective layer includes metal or metal alloy; the material of the welding layer includes metal or metal alloy; the second protection The material of the layer includes metal or metal alloy. The aluminum alloy lead frame according to claim 5, wherein the functional layer is a copper layer; the reflective layer is a silver layer or an aluminum layer; the solder layer is a copper layer; and the second protective layer is a silver layer . The aluminum alloy lead frame according to claim 2, wherein the material of the first protective layer includes a non-metallic low-absorption material. The aluminum alloy lead frame according to claim 7, wherein the first protective layer is a silicon oxide layer. The aluminum alloy lead frame according to claim 2, wherein the thickness of the first intermediate layer and the second intermediate layer is between 2 nm and 1000 nm; the thickness of the functional layer is between 2 nm and 2500 nm; and the thickness of the reflective layer is between 50 nm and 6000 nm The thickness of the solder layer is between 100 nm and 5000 nm; the thickness of the second protective layer is between 50 nm and 1000 nm; and the thickness of the first protective layer is between 0.5 nm and 20 nm. A method for manufacturing an aluminum alloy lead frame includes the following steps: preparing an aluminum alloy substrate having an upper surface and a lower surface opposite to each other; on the upper surface of the aluminum alloy substrate, a first intermediate layer, a A functional layer and a reflective layer, thereby forming a reflective composite layer on the upper surface of the aluminum alloy substrate, the reflective composite layer sequentially including the first intermediate layer, the functional layer and the reflective layer, the first intermediate layer is provided Between the aluminum alloy substrate and the functional layer; and a second intermediate layer, a soldering layer, and a second protective layer are sequentially arranged on the lower surface of the aluminum alloy substrate, so as to be under the aluminum alloy substrate A welding composite layer is formed on the surface, the welding composite layer includes the second intermediate layer, the welding layer and the second protective layer in sequence, the second intermediate layer is disposed between the aluminum alloy substrate and the welding layer to form An aluminum alloy lead frame. The manufacturing method according to claim 10, wherein the reflective composite layer manufactured by the manufacturing method further includes a first protective layer, and the first protective layer is disposed on the reflective layer. The manufacturing method according to claim 10 or 11, wherein the aluminum alloy lead frame produced by the manufacturing method is the aluminum alloy lead frame according to any one of claims 3 to 9.

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