JPH04220179A - Inspecting method for clad band - Google Patents

Abstract

PURPOSE:To continuously inspect a clad state of clad material while being manufactured by a variation of the reflected beam quantity of a laser beam with which an edge of stripe material is irradiated. CONSTITUTION:In the inspection of the clad band used for lead frame material, etc., of a semiconductor integrated circuit, the edge of the stripe material 2 with good electric conductivity is irradiated with the laser beam 5 while passing through the clad band 3 formed by cladding band-shaped base metal 1 and the stripe material 2. The reflected beam is then detected by a photodetector 6. The clad state of the clad band 3 is detected by the variation of a detection symbol for this reflected light quantity. An unclad part 8 of clad band steel thus can be continuously detected in a manufacturing process and the clad band with high reliability can be supplied.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting unpressed portions of cladding bands used in electronic components such as IC packages.

0002

BACKGROUND OF THE INVENTION Materials used for lead frames of semiconductors or semiconductor integrated circuits are composite materials in which two or more metals, one for mechanical strength and the other for electrical conductivity, are combined and clad in a band shape. An example is shown in FIG. FIG. 2 shows the surface of a strip-shaped base material 1 made of a high-strength and corrosion-resistant alloy, such as an Fe alloy such as an Fe-Ni alloy or a Fe-Ni-Co alloy whose coefficient of thermal expansion is close to that of glass, or a Cu alloy. A stripe material 2 having good conductivity, such as Al, which is different from these, is bonded under pressure.

As a method for producing such a clad band, for example, as shown in FIG. 4, as described in Japanese Patent Application Laid-open No. 62-296978, a band-shaped base material 1 is unwound from a base material reel 19, and a similar process is performed. A striped material 2 with good conductivity is fed out from a reel 20 and overlaid on the strip-shaped base material 1, and both are passed through rolling rolls 17 such as 2 to 4 stages of rolls to be cold-pressed and then further rolled. There is a method in which the clad band 3 is obtained by finishing it to a predetermined thickness and winding it. The surface of the strip-shaped base material 1 is generally cleaned by polishing it with a wire brush 16 or the like before being pressure-bonded, and then it is pressure-bonded with a rolling roll 17, and further rolled. The desired plate thickness is obtained, and the cladding band 3 is obtained.

0004

When a cladding band is manufactured by the method using the above-mentioned rolling rolls, poor crimping may sometimes occur at the edge portions of the clad striped material with good conductivity. This poor crimping is mainly caused by poor lubricity between the roll and the material during the process of pressurizing and crimping the materials, which causes the striped material with good conductivity to adhere to the rolling roll and be pulled in the rotational direction of the roll after crimping. It is thought that it has peeled off.

[0005] The cladding band used for lead frames of semiconductor devices and semiconductor integrated circuits is punched into the shape of a lead pin as shown in FIG. 3(a), and then the lead pin 14 is punched out as shown in FIG. An aluminum wire (bonding wire 11) that electrically connects the IC chip 15 to the lead pin 14 is bonded to the good conductive portion 13 at the tip of the lead pin 14 to which the good conductive stripe material 2 is crimped. after that,
The ceramic base 12 and the ceramic cap 10 are sealed with a low melting point glass 19 to form an IC.

[0006] In the bonding process, if there is a partially unpressed portion in the cladding band due to the above-mentioned crimping failure, the bonding will be defective and the function of the IC will be impaired. In order to ensure the high reliability of ICs, it is strongly required to provide materials that are free of defects. Therefore, the uncrimped portion must be detected and removed during inspection.

However, since rolling is further performed after the pressure crimping process, the appearance of the uncrimped part looks no different from the normal crimped part. For this purpose, in the pressure bonding process,
Although it is necessary to detect the unpressed portion, the size of the unpressed portion is very small, 10 to 30 mm on average, and it was impossible to detect it visually.

[0008] For this reason, conventionally, during inspection, adhesive tape was pasted on the stripe material pressure bonding surface of the cladding band.
Then, by peeling off the adhesive tape, the unpressed portion was peeled off and raised, and visually inspected. With this method, it is impossible to inspect the entire length due to efficiency issues, and it has been desired to carry out continuous inspection during the pressure bonding process. An object of the present invention is to provide a method for inspecting a cladding band that performs continuous inspection in a pressure bonding process.

[0009]

[Means for Solving the Problems] The present invention irradiates the edge of the stripe material with a laser beam while passing a clad strip formed by crimping a stripe material onto a stripe base material, and uses an optical sensor to detect the reflected light. This is a method for inspecting a cladding band, which is characterized in that the crimped state of the cladding band is inspected based on the amount of change in the detection signal with respect to the amount of reflected light.

0010

[Operation] The most important feature of the present invention is that the edge of the stripe material is irradiated with a laser beam, and the reflected light is detected by an optical sensor to detect the unpressed portion of the stripe material. This detection method shows that if the stripe material is sufficiently crimped to the base material, the surface near the edge of the stripe material is smooth, and if it is not crimped, the surface is rough and the reflectance of the surface is different. If it is a crimped part,
The amount of change in the detection signal of the sensor is small, and the amount of change in the detection signal of the sensor is large in the uncrimped portion. The crimped state of the stripe material of the cladding band can be inspected based on the difference in the amount of change in the detection signal.

[0011]

[Example] Next, according to FIG. 1, an example of the present invention will be
An explanation will be given by taking as an example a case where an Al foil, which is a good conductive stripe material 2 and having a thickness of 10 μm and a width of 10 mm, is pressure-bonded to a 42% Ni--Fe strip base material having a thickness of 0.2 mm and a width of 40 mm. A sensor main body 7 is disposed 50 mm above the cladding band 3 after pressure bonding, a laser beam 5 is irradiated from the light projecting element 4 to the edge of the Al foil 2, and the reflected light is received by the light receiving element 6.

At this time, if the laser beam 5 is irradiated to the normal part (crimped part), the output 18 of the sensor will be as shown in FIG.
If the uncrimped portion 8 is irradiated as shown in a), the sensor output 18 will be as shown in FIG. 5(b). in this way,
The sensor output is different between the normal part and the uncrimped part. These different outputs make it possible to detect the unpressed portion of the striped material 2 with good conductivity.

Furthermore, due to the difference in reflectance between the strip-shaped base material 1 and the good conductive stripe material 2, the laser beam may be irradiated onto the strip-like base material 1 or the stripe material 2 with good conductivity. The output of the sensor will be different depending on the case. Using this fact, while watching the output 18, the laser beam 5 is
It is possible to irradiate the edges of the striped material 2 with good conductivity. Moreover, by utilizing the difference in the same output, it becomes possible to grasp the positional deviation of the good conductive stripe material 2 in an analog manner, and it also becomes possible to control the position of the good conductivity stripe material 2. In addition, in this example, the maximum feeding speed is 30 m/min, and the laser spot diameter is φ50 ~
φ1000 μm, irradiation angle of laser beam 5 is 45° to 9
At 0°, it was possible to detect the uncrimped portion.

[0014]

According to the present invention, it is possible to continuously detect the uncrimped portion of the clad strip steel during the manufacturing process, and it is possible to supply a highly reliable clad strip.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing an example of detecting an uncrimped portion of a cladding material.

FIG. 2 is a perspective view of a cladding material.

FIGS. 3(a) and 3(b) are a perspective view and a sectional view showing a state in which the clad material is used as a lead frame of an IC.

FIG. 4 is a schematic diagram of an apparatus used for manufacturing cladding material.

FIGS. 5(a) and 5(b) show an example of an output signal of a sensor according to the present invention.

[Explanation of symbols]

1 Band-shaped base material 2 Good conductive stripe material 3 Clad band 4 Light emitting element 5 Laser beam 6 Light receiving element 7 Sensor main body 8 Unpressed area 9 Low melting point glass 10 Ceramic cap 11 Bonding wire 12 Ceramic base 13 Good conductivity at the tip of the lead pin Part 14 Lead pin 15 IC chip 16 Wire brush 17 Roll roll 18 Output signal 19 Base material reel 20 Reel

Claims (1)

[Claims] 1. While passing a clad strip formed by crimping a strip base material and a stripe material, a laser beam is irradiated onto the edge of the stripe material, the reflected light is detected by an optical sensor, and a detection signal corresponding to the amount of reflected light is generated. Depending on the amount of change in
A cladding band inspection method characterized by inspecting the crimped state of the cladding band.