JP4276195B2 - Substrate storage method and coil component manufacturing method - Google Patents

Description

  The present invention relates to a substrate storage method and a coil component manufacturing method in the process of manufacturing, for example, a coil component and the like.

One electronic component having a metal film on the surface of a substrate is a coil component. The coil component includes a substrate and a metal coil formed on the surface of the substrate. As a method for manufacturing such a coil component, for example, as described in Patent Document 1, after a coil pattern is formed on the surface of an insulating substrate via a conductive layer, the conductive portions other than the portion corresponding to the coil pattern are electrically conductive. It is known to remove layers by etching.
JP-A-7-142254

  By the way, depending on the manufacturing process of the coil component, the substrate on which the coil is formed may be stored for a while (for example, several days), and thereafter the conductive layer may be etched. In this case, if the surface state of the substrate deteriorates during storage of the substrate on which the coil is formed, the etching process in the next process may be affected, leading to a decrease in product reliability.

  An object of the present invention is to provide a substrate storage method and a coil component manufacturing method capable of stably storing a substrate on which a metal film is formed.

  In recent years, with the reduction of process rules, etc., in order to stabilize the surface state of a substrate after processing, it is considered that storage of the substrate by a wet method is suitable. However, for example, when the substrate is stored by immersing it in water, there is a problem that the processing variation in the next process (for example, etching or plating) increases depending on the state of the water used. Therefore, as a result of intensive studies, the present inventors have found that the specific resistance of water used for substrate storage and the dissolved oxygen concentration affect the stability of the surface state of the substrate and completed the present invention. I came to let you.

That is, the present invention provides a method for storing a substrate having a metal film formed on the surface, the specific resistance is at 17MΩ · cm or more and the dissolved oxygen concentration is prepared following storage water 50 [mu] g / liter, a metal film The substrate on which the metal film is formed is stored so that the impurity ions contained in the storage water are not adsorbed on the metal film and the metal film is not oxidized before the subsequent processing of the formed substrate is performed. It is characterized by being immersed in water for storage.

  In this way, by using storage water having a specific resistance of 17 MΩ · cm or more and a dissolved oxygen concentration of 50 μg / liter or less, when storing a substrate on which a metal film is formed (hereinafter simply referred to as a substrate), Impurity ions contained are less likely to be adsorbed on the metal surface on the substrate, and the metal surface on the substrate is less likely to be oxidized. This stabilizes the surface state of the substrate even after the substrate is stored.

  Preferably, the storage water is irradiated with ultraviolet light in a state where the storage water is put in the container, and then the substrate on which the metal film is formed is immersed in the storage water. For example, when the substrate is stored in a place other than a clean room, bacteria in the air may enter the storage water and algae may be generated. On the other hand, by irradiating the storage water with ultraviolet light, generation of algae in the storage water is suppressed even when the substrate is stored in the storage water for a long period of time. Thereby, since the deterioration of the water for storage is prevented, the surface state of the substrate can be further stabilized.

  At this time, it is preferable to use a container having a mirror-finished inner wall surface. Thereby, since the ultraviolet rays irradiated to the storage water in the container are easily reflected on the inner wall surface of the container, the ultraviolet rays are sufficiently scattered in the storage water, and the efficiency of the ultraviolet irradiation is increased. Therefore, the generation of algae in the storage water is further suppressed.

The present invention also relates to a method for manufacturing a coil component having a metal coil formed on the surface of a substrate, the step of forming a coil on the surface of the substrate via a conductive layer, and a specific resistance of 17 MΩ · cm. Prepare a storage water having a dissolved oxygen concentration of 50 μg / liter or less and a coil-formed substrate so that impurity ions contained in the storage water are not adsorbed on the conductive layer and the conductive layer is not oxidized. The method includes a step of immersing and storing in a storage water for a predetermined time, and a step of etching a part of the conductive layer after storing the substrate on which the coil is formed for a predetermined time. .

  Thus, in the method of manufacturing a coil component according to the present invention, when storing a substrate on which a coil is formed (hereinafter simply referred to as a substrate), the specific resistance is 17 MΩ · cm or more and the dissolved oxygen concentration is 50 μg / cm 2. By using liters or less of storage water, impurity ions contained in the storage water are less likely to be adsorbed on the conductive layer, and the conductive layer is less likely to be oxidized. This stabilizes the surface state of the substrate even after the substrate is stored. As a result, variations in etching time and the like can be reduced in the conductive layer etching process as the next step.

  According to the present invention, the substrate on which the metal film is formed can be stably stored. As a result, it is possible to reduce variations in processing such as etching processing and plating processing in the subsequent process, so that the reliability of the product can be improved.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a substrate storage method and a coil component manufacturing method according to the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a coil wafer manufactured by an embodiment of a method of manufacturing a coil component according to the present invention. In FIG. 1, a coil wafer 1 includes a disk-shaped insulating substrate 2 and a coil 4 formed in a spiral shape on the surface of the insulating substrate 2 with a conductive layer 3 interposed therebetween. Both the conductive layer 3 and the coil 4 are made of, for example, copper. In FIG. 1, the coil 4 is formed only on one surface of the insulating substrate 2, but the coil 4 may be formed on both surfaces of the insulating substrate 2.

  A method for manufacturing such a coil wafer 1 will be described. First, as shown in FIG. 2, the conductive layer 3 is formed on the surface of the insulating substrate 2 by electroless plating. Then, the coil 4 is formed on the conductive layer 3. Specifically, the coil 4 is formed as follows.

  That is, after a photoresist is formed on the conductive layer 3 by electrodeposition, a coil pattern is formed on the photoresist by photolithography. Subsequently, the coil 4 is formed in a portion where the conductive layer 3 is exposed by electroplating. And after removing a photoresist using a solvent, it wash | cleans. Thereby, as shown in FIG. 2, the board | substrate (henceforth a board | substrate with a coil) 5 with which the conductive layer 3 and the coil 4 were formed in the surface is obtained.

  Thereafter, for a while, the plurality of substrates 5 with coils are stored (stored) together. The temporary storage of the coiled substrate 5 is due to the actual process steps. The procedure for storing the coiled substrate 5 is as follows.

  That is, as shown in FIG. 3, a rectangular container 6 for storing the storage water W is prepared in advance. The container 6 is made of stainless steel, quartz, Pyrex (registered trademark), or the like. The inner wall surface 6a of the container 6 is preferably coated with a reflective film such as Cr. In the container 6, a substrate carrier 7 is disposed for supporting a plurality of substrates with coils 5 in an upright state. The means for supporting the coiled substrate 5 is not particularly limited to this, and for example, the coiled substrate 5 may be supported in a laid state.

  When storing the coiled substrate 5 using such a container 6, first, storage water W is put into the container 6 as shown in FIG. 3. At this time, the storage water W is introduced to such a height that the whole of the substrate with coil 5 is immersed when the substrate with coil 5 is set up on the substrate carrier 7 disposed in the container 6 (see FIG. 4). .

  As the storage water W, ultrapure water having a specific resistance of 17 MΩ · cm or more and a dissolved oxygen concentration of 50 μg / liter or less is used. The reason why the specific resistance of the storage water W is set to 17 MΩ · cm or more is to prevent the impurity ions contained in the storage water W from adsorbing to the conductive layer 3 of the substrate 5 with the coil. The reason why the dissolved oxygen concentration of the storage water W is set to 50 μg / liter or less is to prevent the conductive layer 3 of the coiled substrate 5 from being oxidized. The specific resistance value of the storage water W is set, for example, by passing ultrapure water through an ion exchange tower. The dissolved oxygen concentration of the storage water W is set by removing excess oxygen by applying ultrasonic waves to ultrapure water, for example.

  After pouring such storage water W to a predetermined position in the container 6, as shown in FIG. 3, the storage water W is irradiated with ultraviolet rays (UV) by the ultraviolet irradiation device 8. The reason why the storage water W is irradiated with ultraviolet rays is to prevent the generation of algae in the storage water W. Here, when the inner wall surface 6a of the container 6 is mirror-finished such as a reflection film, the ultraviolet light irradiated to the storage water W is easily reflected by the inner wall surface 6a. For this reason, since ultraviolet rays come to scatter in the storage water W, generation of algae in the storage water W is sufficiently suppressed. Further, since the storage water W is irradiated with ultraviolet rays before the coiled substrate 5 is put into the storage water, the coiled substrate 5 is not damaged.

  Subsequently, as shown in FIG. 4, each of the coil-attached substrates 5 is immersed in the storage water W by supporting the plurality of substrates 5 with the coils on the substrate carrier 7 disposed in the container 6. In addition, you may put the board | substrate carrier 7 of the state in which the board | substrate 5 with a plurality of coils was supported in the container 6 in which the storage water W was stored beforehand.

  Subsequently, as shown in FIG. 5, the inside of the container 6 is sealed by attaching a lid 10 to the upper part of the container 6 via an O-ring 9. In this state, each coil-equipped substrate 5 is stored in the storage water W for a while.

  Thereafter, the substrate 5 with a coil is taken out from the container 6, and the conductive layer 3 located in a portion (coil space portion) S where the coil 4 is not present in the substrate 5 with a coil is removed by etching. Thereby, the coil wafer 1 as shown in FIG. 1 is obtained.

  In the present embodiment as described above, the coiled substrate 5 is stored in a state of being immersed in storage water W having a specific resistance of 17 MΩ · cm or more and a dissolved oxygen concentration of 50 μg / liter or less. Therefore, as described above, when the substrate with coil 5 is stored, the impurity ions in the storage water W are prevented from being adsorbed on the conductive layer 3 and the conductive layer 3 is oxidized. In addition, since the storage water W is irradiated with ultraviolet rays before the coiled substrate 5 is stored in the storage water W, generation of algae in the storage water W is suppressed as described above. Deterioration is prevented. Therefore, since the state of the storage water W is well maintained, the surface state of the coiled substrate 5 is stabilized even after storage.

  As a result, in the subsequent etching process of the conductive layer 3, a decrease in the etching rate is suppressed, so that variations in the etching time and the like for each substrate 5 with a coil are reduced, and the etching processing capability is stabilized. . Moreover, the electrical insulation of the coil wafer 1 can be improved, and a short circuit between the coils 4 can be prevented. As a result, the reliability of the electrical characteristics of the coil wafer 1 can be improved.

  The present invention is not limited to the above embodiment. For example, in the above-described embodiment, the method includes the step of etching the conductive layer 3 provided on the coiled substrate 5 after the coiled substrate 5 is stored. The present invention can also be applied to a case where, for example, the surface of a substrate with a coil is plated after the substrate is stored. In this case, since the substrate with the coil is stored by immersing it in the storage water W as described above, variations in the subsequent plating process can be reduced.

  Further, the substrate storage method according to the present invention is not limited to storage of a substrate with a coil as in the above embodiment, but can be applied to storage of a substrate having a metal film formed on the surface thereof. Further, the present invention can be applied not only to storage of a substrate but also to storage for transporting the substrate.

  Embodiments of the substrate storage method according to the present invention will be described below.

First, a sample of a substrate having a metal film formed on the surface was prepared. Specifically, first, a Cu-laminated glass cloth substrate was prepared. Then, after Cu was etched on the entire surface of the Cu-laminated glass cloth substrate, Cu was formed to a thickness of 0.5 μm on the surface of the glass cloth substrate by electroless plating, and further resisted on the electroless Cu layer by electrodeposition. Was formed to a thickness of 10 μm. Subsequently, a comb electrode pattern of 20 μm × 10 μm was formed by exposure and development, and degreasing cleaning, dilute sulfuric acid cleaning, and pure cleaning were performed on the pattern. Subsequently, electroplating was performed for 30 minutes at a current density of 2 A / dm ² or less to form a 10 μm thick Ni film on the resist. Then, after removing the resist with 1% sodium hydroxide, ultrasonic cleaning and bubble cleaning were sufficiently performed with ultrapure water. This obtained the sample of the board | substrate with which the metal film was formed.

  A plurality (six) of water tanks containing storage water were prepared. The specific resistance and the dissolved oxygen concentration of the storage water contained in each water tank have a combination as shown in FIG. And the board | substrate sample (BG in a table | surface) was immersed in each storage water, and was left to stand in air | atmosphere for 48 hours. One substrate sample (A in the table) was not immersed in storage water but left for 48 hours in the state exposed to the air as it was.

  After elapse of a predetermined time, each sample was taken out and etched using 100 g / liter sodium persulfate (30 ° C.) until the electroless Cu layer in the comb electrode space portion disappeared, and the variation in etching time at that time was examined. . The result is shown in FIG. Note that the variation in etching time here is a variation with respect to 60 seconds. As can be seen from the figure, when storage water having a specific resistance of 17.5 MΩ · cm and a dissolved oxygen concentration of 20 μg / liter was used, the variation in etching time was the smallest (see Sample C).

  Also, each sample was taken out and etched using 100 g / liter sodium persulfate (30 ° C.) for 80 seconds at a level at which the electroless Cu layer in the comb-shaped electrode space was judged to be removed by 40-fold microscopic inspection. Went. Then, a PCT test at 121 ° C., 95% RH, and 120 Hr was performed, and the insulation between the comb electrode patterns was examined. The result is shown in FIG. As can be seen from the figure, the insulation failure occurrence rate between the comb electrode patterns was 0% only when storage water having a specific resistance of 17.5 MΩ · cm and a dissolved oxygen concentration of 20 μg / liter was used ( See sample C).

It is sectional drawing which shows the coil wafer manufactured by one Embodiment of the manufacturing method of the coil components concerning this invention. It is sectional drawing which shows the board | substrate with a coil temporarily stored in the manufacture process of the coil wafer shown in FIG. It is sectional drawing which shows a mode that an ultraviolet-ray is irradiated to the water for storage in a container, before storing the board | substrate with a coil shown in FIG. It is sectional drawing which shows the state which immersed the board | substrate with a coil shown in FIG. 2 in the water for storage in a container. It is sectional drawing which shows the state which has immersed the board | substrate with a coil shown in FIG. 2 in storage water, and is storing it. In an Example, it is a table | surface which shows the method of storing the sample of a board | substrate, and the specific resistance and dissolved oxygen concentration of the water for storage used for storage of the sample of a board | substrate. It is a table | surface which shows the dispersion | variation in the etching time when each sample of the board | substrate shown in FIG. 6 is etched. It is a table | surface which shows the insulation defect incidence rate when each sample of the board | substrate shown in FIG. 6 is etched.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Coil wafer (coil component), 2 ... Insulating substrate, 3 ... Conductive layer, 4 ... Coil (metal film), 5 ... Substrate with a coil, 6 ... Container, 6a ... Inner wall surface, 8 ... Ultraviolet irradiation apparatus, W ... Storage Water.

Claims (4)

A method for storing a substrate having a metal film formed on a surface thereof,
Storage water having a specific resistance of 17 MΩ · cm or more and a dissolved oxygen concentration of 50 μg / liter or less is prepared, and the storage water is used until the post-processing of the substrate on which the metal film is formed. A substrate storage method, wherein the substrate on which the metal film is formed is immersed and stored in the storage water so that the contained impurity ions are not adsorbed on the metal film and the metal film is not oxidized. .   2. The substrate according to claim 1, wherein the storage water is irradiated with ultraviolet light in a state where the storage water is put in a container, and then the substrate on which the metal film is formed is immersed in the storage water. Storage method.   The substrate storage method according to claim 2, wherein the container has a mirror-finished inner wall surface. A method of manufacturing a coil component having a metal coil formed on a surface of a substrate,
Forming the coil on the surface of the substrate via a conductive layer;
Storage water having a specific resistance of 17 MΩ · cm or more and a dissolved oxygen concentration of 50 μg / liter or less is prepared, so that impurity ions contained in the storage water are not adsorbed on the conductive layer and the conductive layer is not oxidized. in a step storing substrate on which the coil is formed is immersed for a predetermined time to the storage water,
And a step of etching a part of the conductive layer after storing the substrate on which the coil is formed for a predetermined time.

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