JP4792734B2 - Contact type film thickness measuring machine - Google Patents

Description

  The present invention relates to a contact-type film thickness measuring machine and a method of using the same, and more particularly to a contact-type film thickness measuring machine for measuring the thickness of a sheet-like electrode material coated with an electrode mixture layer and a method of using the same.

  As electronic devices such as mobile phones, laptop computers, and audiovisual devices have become more sophisticated in recent years, the power batteries used in these devices have become smaller, lighter, larger capacity, and higher energy. Densification is required. Therefore, various non-aqueous electrolyte batteries including lithium ion secondary batteries have been proposed in place of conventional alkaline storage batteries.

In general, a lithium ion secondary battery has terminal electrodes attached to a positive electrode current collector and a negative electrode current collector, wound with a separator for preventing a short circuit between both electrode plates, and filled with a non-aqueous electrolyte. The battery case container is hermetically sealed.
More specifically, the conventional method for manufacturing each current collector of a lithium ion secondary battery is roughly as follows:
a) preparing a long and wide sheet-like current collector metal plate;
b) adjusting the electrode mixture layer coating solution;
c) While periodically running the current collector metal plate in a predetermined direction in order to periodically form a region where the coating liquid (electrode mixture layer) is applied and a region where it is not applied on both sides of the current collector metal plate A step of intermittently applying an electrode mixture layer coating solution;
d) drying the current collector metal plate (simply referred to as web) on which the electrode mixture layer is formed;
e) rolling (pressing) the web;
f) slitting the web into strips in the running direction;
g) winding the current collector slit-cut into strips onto a take-up roll;
h) A part (outermost part) on the outermost side of the electrode material roll once wound on the take-up roll is cut from the entire electrode material roll, and the film thickness of the electrode mixture layer is reduced for the outermost part cut. And measuring.

  The film thickness of the electrode mixture layer applied and pressed on the current collector metal plate has a significant effect on the yield and characteristics of the final product battery, which can be accurately measured with submicron accuracy. Therefore, it is necessary to feed back in real time to the above-described processes, particularly the coating liquid adjustment process and the coating process.

  For example, a conventional apparatus for measuring the thickness of a sheet electrode material is disclosed in Japanese Patent Application Laid-Open No. 2001-126719. This contact-type thickness measuring device is configured as a pair of contact-type displacement sensors disposed to face each other so as to vertically contact both main surfaces of the sheet-like electrode material. Each contact-type displacement sensor has a support post mounted with a spring and a sensor contact having a roller shape fixed to a support plate supported by the support, and responds to movement of the contact position of the sensor contact. And outputs a signal corresponding to the film thickness.

However, according to the contact-type thickness measuring device having such a configuration, the spring is always compressed in order to give elasticity to the contact during use, and the measurement pressure by the spring decreases with time. The sensor contact having a roller shape tends to wear out and wear over time because the spring is easily deteriorated and the elasticity becomes weak. On the other hand, since the sheet-like electrode material travels in contact with the sensor contact, the electrode active material (electrode mixture layer) is damaged in the contact area with the sensor contact, and the product yield as a battery is remarkably increased. There was a problem of reduction.
JP 2001-126719 A

In other prior arts, Micro Fine (registered trademark) manufactured by Union Tool Co., Ltd. is widely used as an apparatus for measuring the film thickness with submicron order accuracy.
As an example, a contact-type film thickness measuring machine of model number S-2 of Micro Fine series manufactured by Union Tool Co., Ltd. will be described below with reference to FIG.

  As shown in FIG. 7, the contact-type film thickness measuring device 101 generally includes a surface plate 110 and a measuring element 120. The surface plate 110 includes a metal table 114 including a placement surface 112 and a predetermined position. The measuring element 120 has a contact surface 112 which faces the mounting surface 112 and is formed into a continuous curved surface (spherical surface) shape or a conical shape including a vertex. The film thickness measuring device 101 measures the thickness of the sheet-like electrode material 130 by sandwiching the sheet-like electrode material 130 between the mounting surface 112 of the surface plate 110 and the contact surface 112 of the measuring element 120.

  The probe 120 is fixed to the lower end of the shaft 124 and is urged downward toward the surface plate 110 by an urging member 126 such as a spring. Further, the shaft 124 is connected to the lever 128, and the shaft 124 and the measuring element 120 can be pulled up when the operator pushes the shaft 124 down. That is, as long as the lever 128 is released, the operator can measure the film thickness by sandwiching the sheet-like electrode material 130 between the surface plate 110 and the measuring element 120. After the thickness measurement is completed, the sandwiching of the sheet electrode material 130 can be released.

  As a preparation before the measurement, the measuring element 120 is gradually lowered to reset the monitor value when the measuring element 120 touches the surface plate 110 to 0, and then the monitor value becomes a predetermined value (for example, −0. 5 mm), the monitor value is reset again to 0 (this value is referred to as the reduction point). Thus, when the monitor value indicates 0, the film thickness measuring device 101 is initially set so that the biasing member 126 biases the shaft 124 and the probe 120 somewhat downward.

However, when the sheet-like electrode material 130 is viewed microscopically, as shown in FIGS. 8A and 8B, the electrode mixture layer 134 applied on the current collector metal plate 132 is not necessarily provided. It does not necessarily have a flat and uniform thickness, but rather may include a localized recess 135. When the measuring element 120 formed into a spherical shape or a conical shape including the apex contacts with the concave portion 135 of the electrode mixture layer 134, the measuring element 120 sinks into the concave portion 135 and has a certain area. The average thickness of the predetermined area cannot be measured.
Similarly, when the electrode mixture layer 134 is made of a soft material, the contact surface 112 of the probe 120 bites into the electrode mixture layer 134 and measures the average film thickness in a specific region. Was difficult.

  As another problem, the table 114 of the surface plate 110 is formed of a metal such as iron as described above, but the sheet-like electrode material 130 is sandwiched between the surface plate 110 and the measuring element 120 to form a sheet shape. While repeating the thickness measurement of the electrode material 130 (FIG. 9A), a part of the table 114 of the surface plate 110 facing the measuring element 120 is worn and worn as shown in FIG. A location 137 is formed. After the formation of the recess 137, when the film thickness measuring device 101 is reset at the position shown in FIG. 10A, the depth d of the recess 137 is set as shown in FIG. Only the thickness is displayed large, and the thickness cannot be measured accurately.

  Yet another problem is that, as described above, in order to measure the film thickness of the sheet-like electrode material 130, the operator only needs to release the lever 128. In some cases, the film thickness is not always accurately measured by pushing up 128 and applying a force more than necessary to the probe 120.

  In order to solve these problems, the present invention is a contact type that can always measure the average film thickness of a predetermined region with high accuracy regardless of the surface shape and constituent material of the electrode mixture layer on the sheet-like electrode material. It aims at providing a film thickness measuring machine.

  It is another object of the present invention to provide a contact-type film thickness measuring device capable of avoiding the formation of a recess due to wear of a part of a table on a surface plate with which a measuring element abuts.

  Furthermore, it is possible to prevent a sudden worker from applying an excessive force to the measuring element and sandwich the electrode mixture layer on the sheet-like electrode material with a stable force by the biasing member. It is an object of the present invention to provide a contact-type film thickness measuring device that can accurately measure the film thickness without causing variations.

The contact-type film thickness measuring machine of the present invention according to claim 1 is:
A contact-type film thickness measuring device for measuring the thickness of a sheet-shaped metal current collector formed of a soft material or having an electrode mixture layer locally having a recess,
A surface plate including a flat mounting surface, a measuring element including a flat contact surface extending in parallel to the mounting surface and having a predetermined contact area, and the mounting surface and the measuring surface of the surface plate. A biasing member that biases the measuring element so as to sandwich the sheet-shaped metal current collector between the contact surface, and a contact area of the contact surface of the measuring element is within the electrode mixture layer or large enough not bite into its local recess, and, rather small enough to eliminate the gap formed between the front according置表surface and the sheet-like metal current collector of the platen, said platen Is characterized in that at least the mounting surface is made of ceramic, and the contact surface of the measuring element has a circular shape with a diameter of 2 mm to 4 mm when viewed from the mounting surface .

According to a second aspect of the present invention, there is provided a contact-type film thickness measuring machine comprising: an actuator that operates to release the thin film member sandwiched between the mounting surface of the surface plate and the contact surface of the measuring element. Also have.

According to the method of using the contact-type film thickness measuring machine of the present invention described in claim 3, after the sheet-shaped metal current collector is rolled, the film thickness is measured before being wound on the winding core. The thickness of the sheet metal current collector is measured using a machine.

According to the method of using the contact-type film thickness measuring device of the present invention according to claim 4 , the sheet-like metal current collector is used by using a film thickness measuring device arranged adjacent to the downstream side of the press roller. Measure the thickness.

  Embodiments of a contact-type film thickness measuring device according to the present invention will be described below with reference to the accompanying drawings. As shown in FIG. 1, the contact-type film thickness measuring machine 1 according to the present invention generally includes a surface plate 10 and a measuring element 20. The surface plate 10 of the present invention includes a ceramic table 14 including a mounting surface 12 and further includes a fixing jig 16 that holds the ceramic table 14 in a predetermined position. On the other hand, the probe 20 of the present invention includes a flat contact surface 22 that faces the mounting surface 12 and has a predetermined contact area. The contact surface 22 of the probe 20 of the present invention preferably has a circular shape, but may have an arbitrary planar shape such as a circular shape or a rectangular shape. The film thickness measuring machine 1 sandwiches the sheet-like electrode material 30 between the mounting surface 12 of the ceramic table 14 of the surface plate 10 and the flat contact surface 22 of the measuring element 20, thereby providing a sheet-like electrode material. A thickness of 30 is measured. The sheet-like electrode material 30 includes a current collector metal plate 32 and an electrode mixture layer 34 coated thereon (see FIG. 2).

  Since the ceramic table 14 is much higher in rigidity than the iron table, even if the contact surface 22 of the probe 20 is repeatedly contacted, the mounting surface 12 of the ceramic table 14 is worn like a conventional iron table. There is nothing. Therefore, as described in the prior art, the thickness of the sheet-like electrode material 30 can be accurately measured without forming a recess in the mounting surface 12 of the ceramic table 14.

  On the other hand, the probe 20 is fixed to the lower end portion of the shaft 24, and a lever 28 is connected to the upper end portion of the shaft 24. The lever 28 is biased to the upper left in FIG. 1 by a biasing member 26 such as a spring. That is, the probe 20 is urged downward by the urging member 26 toward the surface plate 10 via the shaft 24 and the lever 28, and when the lever 28 is pushed down with a force larger than the urging force of the urging member 26, The shaft 24 and the probe 20 are pulled up. Furthermore, the film thickness measuring machine 1 of the present invention is provided with an actuator 40 for operating the lever 28 in the vertical direction. The actuator 40 is a rod 42 that can be vertically expanded and contracted in contact with the lever 28 and a cylinder for driving the rod 42. 44.

  The actuator 40 (rod 42 and cylinder 44) configured in this way can automatically operate the lever 28 in the vertical direction by an operator's switch operation or the like. Therefore, according to the present invention, the sheet-like electrode material 30 is placed between the contact surface 22 and the mounting surface 12 by a stable urging force by the urging member 26 such as a spring without the direct action of the operator. Since it can be pinched, it is possible to realize thickness measurement with little variation due to the work form of the operator.

  As described above, the flat contact surface 22 included in the probe 20 of the present invention can be molded using any technique such as a polishing technique and a cutting technique. Therefore, as shown in FIGS. 8A and 8B, when the electrode mixture layer 34 applied on the sheet-like electrode material 30 has a concave portion locally, or the electrode mixture layer 34 is a soft material. Even if it is comprised by this, since the contact surface 22 of the measuring element 20 of this invention is flat, as shown in FIG. 2, an electrode mixture layer does not dig into the electrode mixture layer 34, as shown in FIG. 34 is in contact with the surface, and the average thickness of a predetermined area area is accurately measured.

  In addition, as shown in FIGS. 3A and 3B, the sheet-like electrode material 30 has undulations (floats) 36, and a minute gap 38 may be formed between the plate-like electrode material 30 and the surface plate 10. Usually, when the probe 20 presses the sheet-like electrode material 30, the gap 38 between the surface plate 10 and the sheet-like electrode material 30 is eliminated as shown in FIG. However, if the contact area of the probe 20 is too large, the urging force per unit area by the urging member 26 becomes small (because the force is dispersed), so that the gap 38 is eliminated as shown in FIG. Not. If the thickness of the sheet-like electrode material 30 is measured in this state, it is displayed larger by the thickness of the gap 38, and the thickness of the sheet-like electrode material 30 cannot be measured accurately.

  That is, when the contact surface 22 of the probe 20 has a curved surface or a conical shape as in the prior art, the contact surface 22 bites into the electrode mixture layer 34, and thus cannot be measured accurately, while the contact surface 22 is too much. In the case of having a wide contact area, the sheet-like electrode material 30 is measured in a state where it floats from the contact surface 22, so that accurate measurement is similarly hindered. Accordingly, the contact surface 22 of the probe 20 will be described in more detail in the examples below, but preferably has a circular shape including a diameter of about 2 mm to about 4 mm, and more preferably includes a diameter of about 3 mm. It has a circular shape.

  By the way, the film thickness measuring machine is conventionally arranged in a quality inspection process independent of the production line, and as described above, the outermost part of the electrode material roll once wound on the winding roll is removed from the entire electrode material roll. It cut | disconnected and conveyed to the film thickness measuring machine in a quality inspection process, and measured the thickness of the cut | disconnected sheet-like electrode material. The sheet-like electrode material cut in this way was discarded after the thickness was measured, but it has a considerable length (for example, several meters), and the unit price per unit length is expensive. The cost was significantly increased.

  Therefore, the film thickness measuring device 1 of the present invention is disposed in the production line, that is, in the process until the sheet-shaped electrode material 30 is pressed and wound around the winding core. Improved to measure thickness inline. More preferably, the thickness of the sheet-like electrode material 30 is measured using the film thickness measuring device 1 disposed adjacent to the downstream side of a press roller (not shown). Note that when the thickness of the sheet electrode material 30 is measured, the travel of the sheet electrode material 30 is temporarily stopped.

Therefore, in order to measure the thickness of the sheet-like electrode material 30, it is not necessary to cut and measure a part of the wound electrode material roll once, and all the sheet-like electrode materials 30 are post-process battery assembly steps. Can be used effectively, and productivity can be significantly improved.
Moreover, since the thickness of the sheet-like electrode material 30 can be measured at any time and the measurement result can be fed back to the related previous process in real time, the thickness management can be realized with higher accuracy.

The following five kinds of measuring elements were prepared, and the thickness of the sheet-like electrode material was measured using a model number TH-R1 (with a ceramic table) of Micro Fine Series manufactured by Union Tool Co., Ltd.
Measuring element S1: It has a continuous spherical contact surface (unprocessed).
Measuring element S2: The contact surface was cut so as to have a circular planar shape with a diameter of 2 mm.
Measuring element S3: The contact surface was cut so as to have a circular planar shape with a diameter of 3 mm.
Measuring element S4: The contact surface was cut so as to have a circular planar shape with a diameter of 4 mm.
Measuring element S5: The contact surface was cut so as to have a circular planar shape with a diameter of 5 mm.

As a preparatory work before measurement by each of the measuring elements S1 to S5, the measuring value is gradually lowered, the monitor value when the measuring element touches the surface plate is reset to 0, and then the monitoring value is a predetermined value. When the value reached (for example, −0.5 mm), the monitor value was reset to 0 again.
As a sheet-like electrode material to be measured, a positive electrode-like sheet-like electrode material sample is prepared, and the thickness is continuously measured 10 times each for the same sample. As a result, the standard deviation of the measured value is as follows: Calculated as follows.

  The diameter of the contact surface of the probe is plotted on the horizontal axis, and the standard deviation (Table 1) of the measured values measured using the probe S1 to S5 is plotted on the vertical axis to obtain the graph shown in FIG.

  As described above, in the case where the contact surface of the probe has a continuous spherical shape (measurer S1), the electrode mixture layer 34 is caused by a local recess or a soft constituent material of the electrode mixture layer. However, the contact surface of the probe was cut into a circular flat shape with a diameter of 2 mm to 4 mm, whereas the variation (standard deviation) of the thickness measured repeatedly (standard deviation) was large (σ = 0.45 μm). (Measurement elements S2 to S4), the standard deviation was about half or less compared to the measurement element S1, and a measurement result with a small variation was obtained. In particular, when the contact surface of the probe has a circular plane shape with a diameter of 3 mm, it was possible to perform measurement with the least variation with respect to repeated measurement values.

  When the diameter of the contact surface of the probe becomes 5 mm or more, the urging force is dispersed as described above, and the thickness is measured with the gap 38 remaining as shown in FIG. Adversely affects variation.

  Therefore, according to Example 1 above, it is concluded that the contact surface 22 of the probe 20 preferably has a circular shape with a diameter of about 2 mm to about 4 mm, more preferably a circular shape with a diameter of about 3 mm. It was.

  Next, using a measuring element having a circular contact surface with a diameter of 3 mm and a surface plate with a ceramic table, the measurement results are less affected by fluctuations due to error factors using the quality engineering method by Taguchi Method. Demonstrated.

  Generally, as the film thickness measuring machine is used every day, the urging member (spring) deteriorates and its urging force becomes weaker, and the reduction point (when reset to -0.5 mm) gradually starts from -0.5 mm. There is a tendency to shift to 0 mm. Even if the urging force and the reduction point fluctuate in this way, it is preferable that the variation with respect to the thickness measurement value is kept small without being affected by this.

Therefore, in the case of using a raw measuring element and a surface plate without a ceramic table (A1), and in the case of using a measuring element having a circular contact surface of 3 mm diameter and a surface table with a ceramic table (A2), The following two conditions (N1, N2) that gave intentional fluctuations to the biasing force and the reduction point of the spring were evaluated for the magnitude of variation in the thickness measurement results.
Condition N1: An unused spring was used, and initial setting was performed so that the reduction point was -0.5 mm.
(Conditions for changing the biasing force and the reduction point so that the measured value is displayed smaller)
Condition N2: Using a deteriorated spring, initial setting was performed so that the reduction point was -0.1 mm.
(Conditions for changing the biasing force and the reduction point so that the measured value is displayed larger)

The following four types of samples (M1 to M4) were prepared as measurement samples, and the true value of the film thickness of each sample was obtained as follows using another standard measuring machine.
Sample M1: 142.8 μm
Sample M2: 147.4 μm
Sample M3: 152.5 μm
Sample M4: 156.4 μm

Then, using an unprocessed probe and a surface plate without a ceramic table (A1), the thickness of the samples M1 to M4 was measured a plurality of times under the condition N1, and the average value was obtained. Similarly, the thickness of the samples M1 to M4 was measured a plurality of times under the condition N2 using an unprocessed probe and a surface plate without a ceramic table (A1), and the average value was obtained.
Further, using a measuring element having a circular contact surface with a diameter of 3 mm and a surface plate with a ceramic table (A2), in conditions N1 and N2, the thicknesses of samples M1 to M4 are measured a plurality of times, and the average value is obtained. Asked.
Thus, the thickness measurement results shown in Table 2 were obtained.

Here, from the measurement results in Table 2, the signal variation (S _T ), effective divisor (r), linear format (L ₁ ), linear format (L ₂ ), proportional term variation (S _β ) for A 1 and A ₂ , The proportional term difference variation (S _{N × β} ), error variation (S _e ), error variance (V _e ), blending error variance (V _n ), and standard deviation (σ) were calculated.

  On the other hand, from the measurement results shown in Table 2, when using an unprocessed measuring element and a surface plate without a ceramic table (A1), a measuring element having a 3 mm diameter circular contact surface and a surface table with a ceramic table were used. In the case (A2), the relationship between the true value and the measured value under the above conditions N1 and N2 was plotted, and the graphs of FIGS. 5 and 6 were obtained. Here, the measurement value of the condition N1 is indicated by a one-dot chain line, the measurement value of the condition N2 is indicated by a straight line, and an ideal case where the true value and the measurement value match is indicated by a broken line.

  As shown in Table 3, the SN ratio in the case of using a measuring element having a circular contact surface with a diameter of 3 mm and a surface plate with a ceramic table (A2) is as follows. When used, the signal-to-noise ratio is significantly improved (−0.27 db to 5.59 db), and the variation (σ) of the measured value of A2 is also much smaller than that of A1. Yes. That is, as in the present invention, using a measuring element having a circular contact surface with a diameter of 3 mm and a surface plate with a ceramic table, even if there is a variation in the biasing force and the reduction point of the spring, it is not easily affected. This means that measurement with little variation is realized.

  Similarly, in the graphs shown in FIG. 5 and FIG. 6, in the case of A2 than in the case of A1, the straight line indicating the measured value and the one-dot chain line are closer to the broken line indicating the ideal case. It was demonstrated that the measurement results were less susceptible to fluctuations due to error factors (biasing force and reduction point) when using a probe with a circular contact surface and a surface plate with a ceramic table.

It is a schematic front view of the contact-type film thickness measuring machine of this invention. It is an enlarged front view which shows the state which measures the thickness of the sheet-like electrode material which has an electrode mixture layer containing a recessed part using the film thickness measuring machine shown in FIG. It is a front view which shows the state which measures the sheet-like electrode material which has a wave | undulation using the film thickness measuring device shown in FIG. It is a graph which shows the relationship between the diameter of the contact surface of a measuring element, and the standard deviation of a measured value. It is a graph which shows the relationship between the measurement result in two conditions which give an error factor, and a true value at the time of using an unprocessed measuring element and a surface plate without a ceramic table. It is a graph which shows the relationship between the measurement result in two conditions which give an error factor, and a true value at the time of using the measuring element which has a circular-shaped contact surface of 3 mm diameter, and a surface plate with a ceramic table. It is a schematic front view of the contact-type film thickness measuring machine by a prior art. It is an enlarged front view which shows the state which measures the thickness using the conventional film thickness measuring machine with the sheet-like electrode material which has an electrode mixture layer containing a recessed part. It is the schematic which shows the recess formed by abrasion when the conventional metal table contact | abuts repeatedly with a measuring element. It is the schematic which shows the sheet-like electrode material by which thickness measurement is performed after resetting in the state in which the recess was formed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Contact type film thickness measuring machine, 10 Surface plate, 12 Mounting surface, 14 Ceramic table, 16 Fixing jig, 20 Measuring element, 22 Contact surface, 24 Shaft, 26 Energizing member (spring), 28 Lever, 30 Sheet electrode material, 32 current collector metal plate, 34 electrode mixture layer, 36 swell (floating), 38 gap, 40 actuator, 42 rod, 44 cylinder 44.

Claims (4)

A contact-type film thickness measuring device for measuring the thickness of a sheet-shaped metal current collector formed of a soft material or having an electrode mixture layer locally having a recess,
A surface plate including a flat mounting surface;
A measuring element including a flat contact surface extending parallel to the mounting surface and having a predetermined contact area;
An urging member for urging the measuring element so as to sandwich the sheet metal collector between the mounting surface of the surface plate and the contact surface of the measuring element;
The contact area of the contact surface of the measuring element is large enough not to bite into the electrode mixture layer or a local recess thereof, and the mounting surface of the surface plate and the sheet-shaped metal current collector rather small enough to eliminate the gap formed between the,
The surface plate has at least the mounting surface made of ceramic,
The contact-type film thickness measuring machine , wherein the contact surface of the measuring element has a circular shape with a diameter of 2 mm to 4 mm when viewed from the mounting surface .   The film thickness measuring machine according to claim 1, further comprising an actuator that operates to release the thin film member sandwiched between the mounting surface of the surface plate and the contact surface of the measuring element. A method of using the film thickness measuring device according to claim 1,
A film characterized by measuring the thickness of the sheet-shaped metal current collector using a film thickness measuring machine after the sheet-shaped metal current collector has been rolled and before being wound around the winding core How to use the thickness measuring machine. The usage method according to claim 3 , wherein the thickness of the sheet-shaped metal current collector is measured using a film thickness measuring device arranged adjacent to the downstream side of the press roller. .

Images