JPS6161003A - Method and instrument for measuring thickness of plating layer by x rays - Google Patents

Abstract

PURPOSE:To measure with a high accuracy and by on-line a thickness of a plating part formed on the surface of a basis material by bringing an X-ray tube bulb to pulse-driving while making it synchronize with the repeat pattern of an object to be measured, and detecting generated fluorescent X rays. CONSTITUTION:A measured part detector 1, an X-ray tube bulb 11, an X-ray detector 12, a multi-channel analyzer 15, a CPU16, etc. are provided on a part of an electric circuit. In this case, the plating layer and the basis material of an object to be measured which has received an irradiation of X rays emitted from the X-ray tube bulb 11, emit fluorescent X rays. This fluorescent X rays are converted to an electric signal by the X-ray detector 12, subjected to a synchronizing rectification by a switch 14, and inputted to the analyzer 15. The analyzer 15 discriminates a signal component based on the plating layer and outputs it to the CPU16. The CPU16 calculates the thickness of the plating layer based on the inputted signal. When the time corresponding to an X-ray tube driving pulse width elapses, the switch 10b of an electric power source 10 becomes off, and the radiation of X rays is stopped. When the object to be measured moves and the next base part is opposed to the detector 1, the signal is outputted again.

Description

Detailed Description of the Invention (Technical Field) The present invention relates to a fluorescent X-ray film thickness measuring method for measuring the thickness of a plating layer applied to a minute member having a repeated pattern;
and an apparatus for carrying out the same.

(Prior technology) To streamline the manufacturing process, connector bins and semiconductor lead frames are manufactured by continuously forming units by punching a band-shaped substrate into a predetermined shape using a press, plating the main parts, and then cutting into units. Produced by separating.

The quality of such electrical components is greatly influenced by the thickness and uniformity of the plating layer, so it is necessary to control the plating process.

For this purpose, a sample is taken by cutting a part of the continuously formed strip, and the plated area of this sample is irradiated with excitation X-rays, and then the plated layer is evaluated based on the intensity of the fluorescent X-rays emitted from the plated layer. , the thickness of the ki layer has been measured.

However, there was a problem in that the inspection results could not be fed back to the plating T-culm because there was a large time lag between the plating process and the inspection process.

To solve this problem, we continuously irradiate the object to be measured with excitation X-rays while it is running as a strip, detect the fluorescent X-rays from the plating layer, and measure the thickness of the plating layer continuously. A method of measuring the distance has also been proposed, but since the measurement area is extremely large, only average data can be obtained.
There was a problem that precise management was not possible.

(1) In view of these problems, an object of the present invention is to propose a method for online measuring with high accuracy the thickness of a plating layer at a plating site formed on the surface of a substrate having a repeated pattern. .

Another object of the invention is to provide a device for carrying out the method described above.

(Structure I &) In other words, the feature of the present invention is that the X-ray tube is driven in pulses in synchronization with the repeating pattern of the object to be measured, and the fluorescent X-rays generated thereby are detected. be.

Therefore, details of the present invention will be explained below based on illustrated embodiments.

FIG. 2 shows the external appearance of an apparatus showing an embodiment of the present invention, and the reference numeral 19 in the figure indicates an X-ray tube 11, an X-ray detector 12 such as a proportional counter, a tool scope 18, and The measuring head houses a shutter block, etc., and is connected vertically to a head lifting guide 21 set upright on a base 20 and a ball screw 23 for lowering the measuring head A, which is rotationally driven by a pulse motor 22 housed in the base 20. movably mounted. Reference numeral 24 denotes an object support rod installed on the base 20 so as to be located in front of the X-ray irradiation port of the measurement head 19, and includes, from the top, a sample guide 25, a standard sample holder 26, and a plating solution sample holder 27. is installed. The sample guide 25 is configured such that a pair of guide rolls 25a and 25a are disposed on a frame 25b and are spaced apart below, and are engaged with sprockets formed on both sides of the object to be measured to guide it in the horizontal direction. has been done.

These head elevation guides 21 and ball screws 23
A top plate 28 is attached to the second part of the object support rod 24, and shutter open/close indicator lamps 29a and 29b, which will be described later, are attached to indicate the open/closed state of the shutter block.

FIG. 3 shows an embodiment of the measuring head,
The reference numeral 11 in the figure is the aforementioned three-model X-ray tube that can be driven by pulses, and Xl! The radiation port 11a is arranged to face a measurement window 19b formed in the measurement head. Reference numeral 12 denotes an X-ray detector such as a proportional counter tube, which is arranged so that fluorescent X-rays emitted from the plating portion of the object to be measured enter the detection port.

Reference numeral 18 denotes a tool scope consisting of a television camera or the like, which is arranged so as to photograph the object to be measured through the optical path of a shutter block 30, which will be described later. Reference numeral 30 denotes the aforementioned shutter block, which slides between the protrusion 30a provided on the negative side and the two positioning pins 19a, 19a provided in the head in the direction perpendicular to the object transfer path X-x. then 1
- Provided to take the bottom two positions. The radiation of the X-ray tube 11 on the upper side of the shutter block 30 [111
An X-ray collimator 17 is placed on the axis connecting a and the irradiation area of the object to be measured.
In the axial direction perpendicular to the collimator axis, two mirrors 30b and 3 are attached so as to connect the tool scope 18 and the observation window 19c formed in the measurement head 19.
0c is arranged, and the first optical path from the observation window 19c to the tool scope is formed (Ib).
collimator 17 of shutter block 30 parallel to the optical path of
Two mirrors 30d and 30e are arranged to connect the lower side and the tool scope 18, and a second optical path is formed from the measurement window 19b drilled in the measurement radar 19 to the tool scope 18. In FIG. IIb), a strobe lamp 8.7 is provided in the measurement window 19b and the observation window 19c.

FIG. 1 shows an embodiment of an electric circuit for driving the apparatus of the present invention, and reference numeral l in the figure indicates a light emitting element 1a arranged in an oblique manner across the conveyance path x-x of the object to be measured T. and light receiving element 1
1 is a part-to-be-measured detector consisting of a part to be measured detector 1, which is configured to output a signal when the end of each pattern of the object to be measured crosses the optical axis of the detector 1. 2.3.4 is an observation point lamp light emission timing signal generator, a measurement point lamp light emission timing signal generator, and an X-ray tube, which are each composed of a delay circuit whose delay time can be adjusted by variable resistors 2a, 3a, and 4a. This is a drive timing signal generator. Reference numerals 5.6 and 5.6 each designate a strobe lamp drive circuit which outputs pulsed power to drive the strobe lamp 7.8 in a controlled manner using the signal from the lamp emission timing signal generator 2.3 as a trigger.

Reference numeral 9 denotes an X-ray tube drive circuit consisting of a monostable multivibrator whose pulse width can be adjusted by an external resistor 9a, which generates a pulse signal of a constant width in synchronization with the signal from the X-ray tube drive timing signal generator 4. The first output will be output and will be described later. Wg2
The switches 10a and 14 are turned ON-OFF. 10 is a power supply circuit for an X-ray tube, which includes a high-voltage power supply 10a connected between the anode and cathode of the X-ray tube 11 via a resistor 10d, and a first switch 10b connected to both ends of the resistor 10d. connected and superimposed on the high voltage power supply 10a,
It consists of a bias power supply 10c that drives the wire tube 11 at instantaneous rating. 12 is an X-ray detector such as a proportional counter that detects fluorescent X-rays from the object to be measured; the detection signal from this is amplified to a predetermined level by a preamplifier 13;
The signal is input to a multi-channel analyzer 15, which will be described later, via a second switch 14 that is synchronized with the intermittent operation of the X-ray tube 11. 15 is the multi-channel analyzer mentioned above, which distinguishes fluorescent X-rays from the target element such as the plating layer from the detection signal and measures the intensity thereof; 16 is the CPU, which measures the signal from the multi-channel analyzer. Based on this, the thickness of the plating layer is calculated and the operation of the entire device is controlled.

In the figure, reference numeral 17 indicates a collimator disposed in front of the X-ray tube, and 18 indicates a tool scope for detecting an optical image of the object to be measured at observation point M and measurement point A, respectively.

In this example, the standard sample is placed in the sample holder 26.
The measurement window 19b of the measurement head 19 is set to face the standard sample, and the device is operated to obtain the detection line.

Next, an object to be measured such as an elongated lead frame is set on the sample holder 25, and transfer of the object to be measured is started.

(i) Adjusting the emission timing of the observation point lamp To measure, move the shutter block 30 housed in the radar 19 to the first position to form a first optical path from the observation window 19C to the tool scope 18. In FIGS. Ia and Ib), while looking at the tool scope 18, the delay time of the observation point lamp light emission timing signal generator 2 is adjusted so that the object to be measured appears stationary. As a result, the strobe lamp 7 emits light every time the pattern base T of the object to be measured reaches the measurement window 19b, and the object to be measured is photographed by the tool scope 18 and displayed as a still image on a monitor cathode ray tube (not shown).

(11) Adjusting the light emission timing of the measurement point lamp Move the shutter block 30 to the second position to form a second optical path from the measurement window 19b to the tool scope 18.
2a, 11b), while looking at the tool scope 18, the delay time of the measurement point lamp emission timing signal generator 3 is adjusted so that the object to be measured appears stationary.

(iii) Adjustment of X-ray irradiation timing The shutter block was moved to the first position and the collimator 17 was arranged to face the irradiation port 11a of the X-ray tube 11, and was formed at the base T of the object to be measured. The delay time of the X-ray tube drive timing signal generation circuit 4 and the pulse width of the X-ray tube drive circuit 9 are adjusted so that the aiming light hits the plating layer.

After completing such preparations, the apparatus is operated and the object to be measured is transferred. As a result, when the end of the base T forming the pattern of the object to be measured crosses the optical axis of the object to be measured detector 1,
The measurement site detector l outputs a pulse signal to the X-ray tube drive timing signal generation circuit 4, the observation point lamp emission timing signal generation circuit 2, and the measurement point lamp emission timing signal generation circuit 3 (FIG. 4). As a result, the X-ray tube drive circuit 9 outputs a pulse signal to turn the switch 10b on.
Switching from FF to ON, the voltage from the bias power supply 10c is superimposed on the X-ray tube high-voltage power supply 10a, and an instantaneous rated drive voltage is applied to the X-ray tube 11. The X-rays emitted from the X@tube 11 are focused into a narrow beam by the collimator 17 and irradiate a part of the base T of the object to be measured. The plating layer and the base material in the area irradiated with this X-ray are excited, and the intensity of the fluorescent X-rays corresponds to the thickness of the plating layer and the constituent elements.
rays and fluorescent X-rays corresponding to the constituent elements of the substrate. Fluorescent X-rays emitted from the plating layer and the base material are converted into electrical signals by the X-ray detector 12, subjected to synchronous rectification by the switch 14, and sent to the multi-channel analyzer 1.
Enter 5. The multi-channel analyzer 15 is
A signal component based on the plating layer is discriminated from among the input signals and outputted to the CPU 16. The CPU 16 calculates the thickness of the coating layer based on the signal input from the multi-channel analyzer 15, outputs it to a display meter or printer (not shown), and further outputs it to a plating processing device (not shown) to determine the transfer speed of the plated member. Then, the current density of the plating bath, the concentration of the plating solution, etc. are adjusted so that the thickness of the plating layer becomes the set value.

In this way, the time corresponding to the X-ray tube driving pulse width is 1.
When , the switch tab of the X-ray tube power supply 10 is turned OFF, and the emission of X-rays is stopped. When the object to be measured moves and the next base faces the detector 1, a signal is output again, and the thickness of the plating layer is measured through the process described above.

Thereafter, while repeating such a process, the base portion is selectively irradiated with excitation X-rays to measure the thickness of the plating layer.

When the shutter block 30 is moved to the second position in order to observe the behavior of the object to be measured in the measurement area, the X-ray tube method power supply lO is turned off by a shutter changeover detection switch (not shown), and at the same time the shutter closed indicator lamp 29 is turned off.
b lights up.

In this example, the movement of the object to be measured is detected by detecting the part to be measured, but it is also possible to detect movement that is synchronized with the movement of the part to be measured, such as by detecting a sprocket formed for transportation. However, the same effect can be obtained even if the control is performed based on this signal.

(Effects) As explained in 1-1 below, according to the present invention, the driving voltage applied to the X-ray tube is intermittently pulse-driven in correspondence with the repetitive pattern formed on the long object to be measured. This not only makes it possible to obtain high X-ray output by operating a small X-ray tube at a high instantaneous rating with a high peak output, improving statistical accuracy and reducing the weight of the device, but also allows for more space in the measurement area. Since X-rays are selectively irradiated only when the object to be measured is present, the X-rays are blocked by the object to be measured, and leakage of X-rays to the external environment can be minimized.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of an apparatus showing an embodiment of the present invention;
FIG. 3 is a perspective view of the device showing an embodiment of the present invention, FIG. 3 is a plan view of the device showing an embodiment of the measuring head used in the same device, and FIG. 4 is a diagram showing the operation of the device. FIG. 3 is a waveform diagram for explanation. l...Measurement area detector 7.8...Strobe lamp lO...X-ray tube drive power supply 11...X-ray tube 1
2...X-ray detector 17...Collimator 1
8...Tool scope 19...Measuring head 2
5...Sample holder T...Base applicant
Seiko Electronic Industries Co., Ltd. Representative Patent Attorney Kei Nishikawa Katsuhiko Kimura) q) w&Φ ~ 81 rtsuru 1. ′(IC> η 1 \ 1 t1 -m-mi sa. /-ゝ8 to / s IX.

Claims (2)

[Claims] (1) While conveying a strip-shaped object to be measured that is continuously formed with a repeating pattern, an X-ray tube is operated intermittently in accordance with the pattern to detect fluorescent X-rays generated from the plating layer. How to measure the thickness of the plating layer. (2) A means for detecting the moving state of a strip-shaped object to be measured that is continuously formed with a repeating pattern, an X-ray tube that operates intermittently in synchronization with a signal from the means, and Thickness of a plating layer by X-rays, comprising an X-ray detection means for detecting fluorescent X-rays, and a means for calculating the thickness of the plating layer by discriminating a fluorescent X-ray signal based on the plating layer from the signal of the X-ray detection means. measuring device.