JPH02181995A - Dust prevention and dust removal methods for electronic circuit boards, and protective materials - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to the protection of objects that dislike dust, and in particular, a dust prevention method, a dust removal method, and a dust removal method suitable for protecting high-density electronic circuit boards.
and regarding protective materials.

[Prior Art] When dust adheres to electronic circuit boards, especially high-density electronic circuit boards such as Tama wiring boards, during the manufacturing process, this dust is removed during the formation of circuit patterns, through-holes, etc. This causes a problem in that it becomes a failure and causes a defect in one circuit pattern or through hole.

For example, in the case of ceramic green sheets forming a ceramic multilayer wiring board used for mounting LSI etc., each of the plurality of green sheets.

A multilayer wiring board is formed by forming circuit patterns, through holes, etc., and stacking them. Therefore, if dust adheres to the green sheet, the inner layer may peel off during lamination, or
rFr wire, causing short circuits, etc.

Therefore, for this type of electronic circuit board.

Countermeasures against dust are being considered.

Conventionally, as such a countermeasure, a
Cover the surfaces that need to be protected from dust with a protective sheet.
This prevents dust from adhering. For example, in the case of a ceramic green sheet, it is necessary to protect both sides, so by sandwiching the green sheet with a protective sheet, it is possible to prevent dust from adhering to it. Even if dust is floating in the area where the electronic circuit board is exposed, it is covered with a protective sheet.

No dust attached.

Conventionally, as such a protective sheet, electric
For example, materials with excellent toughness, heat resistance, cold resistance, and chemical resistance that do not generate dust are selected and used6.

Polyester film is used.

[Problems to be Solved by the Invention] The above-mentioned conventional techniques are good as long as the electronic circuit board is covered with a protective sheet.

When removing the protective sheet, f! There is a problem in that the electronic circuit board is charged and the floating dust is electrostatically attracted to it, causing t1 dust to adhere to it.

This will be explained with reference to FIG.

That is, when the ceramic green sheet 3 is sandwiched between the protective sheets 2 as shown in FIG. At this time, when the ceramic green sheet 3 is subjected to shaking or the like, friction is generated between the ceramic green sheet 3 and the protective sheet 2, and as a result, an electric charge 7 is induced. Furthermore, when the protective sheet 2 is peeled off from the ceramic green sheet 1-3, friction occurs and the protective sheet 2 is similarly charged. If such a charge 7 exists, as shown in the same figure (Q),
The fli field 6 is generated, and the floating dust 8 is attracted by Coulomb force and adheres to the ceramic green sheet 3.

Therefore, with regard to dustproofing electronic circuit boards, the conventional dustproofing method has had the problem of preventing dust from adhering to it due to -JiFm when the protective sheet is removed.

On the other hand, as mentioned above, ceramic green sheets
Processing waste is generated to make through-hole holes. Some of this processing waste adheres to the ceramic green sheet, causing problems such as inner layer peeling, disconnection, and short circuits, similar to the case of foreign dust adhesion.

In the case of such dust, since it is not foreign, it cannot be prevented by the above-mentioned protective sheet. Similarly, the above-mentioned protective sheet cannot prevent dust that has already adhered, and therefore, it may be necessary to take measures to protect against such dust.

However, conventional measures to prevent such dust have not been considered at all. Therefore, in addition to the dust prevention mentioned above,
Dust removal to remove such dust has also become a problem to be solved.

An object of the present invention is to prevent the generation of static electricity and the adhesion of floating dust. An object of the present invention is to provide a dustproof method for electronic circuit boards.

Another object of the present invention is to provide a method for removing dust from an electronic circuit board, which can capture and remove dust that has already adhered.

Still another object of the present invention is to provide a protective material suitable for carrying out the dust prevention method and dust removal method.

[Means to solve the problem] Mokumon is used as a means to solve the above problems.

The following invention is provided.

The first invention is an invention of a dustproof method for an electronic circuit board, which includes covering a surface of the electronic circuit board that needs to be protected from dust with a protective material made of a material that does not easily charge the electronic circuit board. It is characterized by

The second invention is fl! An invention of a method for removing dust from a sub-circuit board, comprising: covering a surface of an electronic circuit board that needs to be protected from dust with a flexible protective material having a large number of recesses on one surface; The present invention is characterized in that the dust on the surface of the electronic circuit board is removed by relatively displacing the protective material and trapping the dust.

The third invention is an invention of a method for preventing and removing dust from an electronic circuit board.

A surface of an electronic circuit board that needs to be protected from dust is covered with a protective material that is made of a material that is flexible and does not easily flood the electronic circuit board, and has a large number of recesses on one surface. By relatively displacing the and electronic circuit board, and capturing dust by the protective material, ? ! It is characterized by removing dust from the surface of electronic circuit boards.

The fourth invention is an invention of a protective material.

It is characterized by having a large number of recesses on its surface and being made of a flexible material that, when covered with an object, adheres closely to the surface of the object and easily captures dust on the object.

The fifth invention is an invention of a protective material.

Made of a material that has many recesses on its surface, is flexible, and when covered with an object, it adheres closely to the surface of the object, easily traps dust on the object, and does not easily charge the object. It is characterized by becoming.

A sixth invention is an invention of a dust prevention/dust removal method for an electronic circuit board, which protects the electronic circuit board from a material that is flexible and difficult to charge, and has a large number of recesses on the surface. It is characterized by being sandwiched between materials for transportation, storage, and other handling.

The material for the protective material is preferably a material that does not itself generate dust, whether for dust prevention or Δ removal, and also because it adheres closely to the surface of the object so as not to create a gap between the protective material and the object. A flexible material with low rigidity is preferable. For example, a sheet-like material can be mentioned. The area is preferably larger than the area of the surface of the object to be covered.

In addition, when using a seamill-shaped material, the peripheral portion tends to generate chips, etc., so it is preferable to use this portion by folding it to the side that does not come into contact with the object.

In addition, in the case of dustproofing, a material whose triboelectric ranking is equal to or similar to that of the object is used as a material that is difficult to charge an object such as an electronic circuit board. It is also conceivable to use a material that has conductivity. In these cases, the material.

Conditions for selection include not damaging the surface of the green sheet, etc., and not forming streaks.

When cleaning, it is necessary that the protective material be able to capture dust. For this purpose, it is preferable to use a material that has concave portions on its surface and can capture Im dust due to the concave and convex portions. Examples of materials that form such a surface shape include mesh,
Pores, etc. may be considered.

Examples of the material include woven fabric, nonwoven fabric, and porous sheet. More specifically, long fiber nonwoven fabrics of cotton may be mentioned. The reason for using long fibers is that they are less likely to generate dust.

Note that the protective material of the present invention is fl! Child circuit boards, especially
Suitable for removing Δ and dustproofing ceramic green sheets, but can also be applied to other objects! [Function] The present invention provides an electronic circuit board! The surface of the electronic circuit board that needs to be protected from alkaline dust must be heated to 1 iF? ! By coating with a protective material made of a material that is difficult to charge, it is difficult to charge electricity even when the protective material and the electronic circuit board rub against each other, not only during the coating but also when the protective material is peeled off. It is possible to prevent floating dust from adhering to the circuit board.

Another aspect of the present invention is that the electronic circuit board is 1g! 1. Covering a surface that needs to be protected from dust with a flexible protective material having a large number of recesses on one surface, displacing the protective material and the electronic circuit board relative to each other, and capturing dust with the protective material, Removes dust on the surface of electronic circuit boards.

leave

The mechanism by which dust is captured by the protective material is not necessarily clear, and it is thought that various actions are at work. Here, the following effects will be explained.

In other words, due to the relative displacement between the protective material and the electronic circuit board,
Is the opening wall of the recess in the protective material ′? It acts to scrape away the dust adhering to the surface of the r1 child circuit board, and in the process, the dust is thought to be captured by penetrating the flexible protective material, embedding in the recesses, etc. .

In addition, even if you just cover it with a protective material, dust can get onto the protective material.
It may also stick or fit into a recess. Therefore, although displacement is not necessarily required, in order to remove dust more reliably, it is preferable to include displacement.

When there are many recesses, the relative displacement may be such that the opening wall surface of the recesses rubs the surface of the electronic circuit board almost evenly. Therefore, the amount of displacement can be extremely small. Moreover, the displacement may be unidirectional, reciprocating, or the like.

Therefore, it is practically not necessary to move the protective material. Therefore, when the electronic circuit board is covered with the protective material, the protective material is not displaced.

A slight displacement when peeling off the protective material is sufficient.

By using a flexible material as the protective material, the protective material can be brought into close contact with the surface of an object such as an electronic circuit board. Due to this.

Since no gap is created between the surface of the object and the protective material,
It is possible to prevent dust from entering through the gap. Further, by coming into close contact with the surface of an object such as an electronic circuit board, the dust removal effect of the protective material functions effectively.

In addition, it is preferable to use a long-fiber material because it reduces bleeding of the material and also ensures flexibility. Particularly, in the case of ceramic green sheets, it is preferable to use long-fiber nonwoven fabric of cotton. green sheet,
without any damage.

Moreover, it is preferable because the drilling process H can be easily captured.

[Example] Hereinafter, nine examples of the present invention will be described in detail with reference to one drawing.

FIG. 1 and FIG. 2 show an example of dust prevention during conveyance and storage of ceramic green sheets.

In FIG. 1, a ceramic green sheet 3 is a sheet-like protective material 9 placed on an aluminum tray 1.
8, and another protective material 9a is placed on top of this.
't'l gets hit. That is, the ceramic green sheet 3 is sandwiched between two protective members 98, and the receiver is placed on the plate 1.

In this embodiment, cotton cloth is used as the protected forest 9a.

This protective material 9a is larger than the outer shape of the ceramic green sheet 3, and completely covers the ceramic green sheet 3 up to its periphery, thereby preventing dust from entering from the periphery.

This tray 1 is inserted into the guide rail 5 of the transport box 4 shown in FIG. 2, and is stored in the transport box 4.

Then, while stored in the transport box 4, it is subjected to handling such as movement, transportation, storage, etc. For example, thick film printing,! t
W! J, and are sequentially sent to each process such as firing.

Then, in each step, the product is taken out from the transport box 4, the protective sheet 9a is removed, and the product is subjected to necessary processing.

In the state up to this point, the ceramic green sheet 3 is
Since the green sheet 3 is covered with the protective material 9a, foreign dust is blocked by the protective material 9a and does not adhere to the green sheet 3.

Dust-proof.

In addition, the ceramic green sheets 3 are sandwiched between the protective materials 9a and undergo relative displacement and friction with each other during movement, etc. However, the protective materials 9a made of cotton cloth are difficult to charge the ceramic green sheets 3. So it doesn't induce a charge, and therefore after.

Even when the protected forest 9a is peeled off from the ceramic green sheet 3, the protected forest 9a does not charge the ceramic green sheet 3.

This will be compared with the case where the polyethylene film 2a shown in FIG. 4 is used as a protective sheet.

The dustproofing shown in Figure 4 is W! , the load is induced and f! ! 6 is occurring. On the other hand, in the fifth embodiment, as shown in FIG. 5, no electric charge is induced and therefore no electric field is generated.Therefore, according to the first embodiment, dust is not electrostatically attracted. Therefore, IIM J/A is prevented from adhering to the surface of the ceramic green sheet 3.

Next, other embodiments of the present invention will be described.

This example shows an example of a dust removal method and a protective material therefor.

According to the embodiments described above, adhesion of foreign dust can be almost completely prevented. However, dust 1 from processing H etc. generated during drilling of ceramic green sea 1-
0 is attached from the beginning, as shown in FIG. Therefore, even if it is later covered with the protective sheet 211, this cannot be removed as shown in FIG. 7. Therefore, in this embodiment, it is possible to remove the already attached dust. An example of a protective material and method thereof is shown.

Although not shown in the drawings, in this example, as shown in FIG. 1, the ceramic green sea 1-3 is stored between the sheet-shaped protected forests 9b, 9b, and then the ceramic green sea is stored as shown in FIG. Next, dust is removed by tearing up the protected forest 9b.

The protected forest 9b used in this example is as shown in FIG.
In this embodiment, a sheet-like material made of a flexible material and having a large number of recesses on its surface is used, and a long fiber nonwoven cotton fabric is used.

This protective material 9b has a mesh made of cotton fibers, and has a large number of recesses 9c as shown in an enlarged view in FIG. 9(b).
have.

Further, this protected forest 9b can be used by cutting a long sheet wound into a roll according to the ceramic green sheet 3 to be protected. In this case, the cutting dimension is made larger than the outer diameter of the ceramic green sheet 3.

In addition, when using the cut protective material 9b as described above, there is a risk that cut eyebrows may appear from the cut portion, so it is preferable that the 5 meridian portions be coated with ceramic green as shown in FIG. The ceramic green sheet 3 is folded back to the side that does not touch the sheet 3, that is, the ceramic green sheet 3 is covered by the area indicated by diagonal lines in the figure.

If such a protective material 9b is used to cover the ceramic green sheets 1 and 3, the protected forest 9b will sway due to vibrations during storage, and the protected forest 9b and the ceramic green sheets 3 will be separated. be relatively displaced. As a result, the recess 9
It is thought that the wall surface of the opening c acts to scrape off dust adhering to the surface of the ceramic green sheet 3. As a result of this action, dust is trapped by penetrating the flexible protective material 9b or being embedded in the recess 9c as shown in FIG. 9(b).

Therefore, when the protected forest 9b is peeled off, the captured dust 10 is peeled off from the surface of the ceramic green sheet 3 together with the protective material 9b, as shown in FIG.

When the surface of the protective material 9b that has been peeled off in this way is observed under a microscope, it can be seen that the dust 10 is captured in various ways. FIG. 13 shows this typical embodiment.

FIG. 13 shows a cross section of a part of the protected forest 9b.

In the same figure, the aspect indicated by Q is the imaged part of the m-fiber.

This is a state in which dust 10 is captured. Moreover, the aspect shown by b is a state in which dust 10 is captured in the recessed portions of the fibers. Furthermore, in the embodiment shown by C, the dust 10 is
It is in a state where it is captured in the hole that exists in c.

In addition, the protected forest 9b and the ceramic green sheet 3 are
Even if there is no relative displacement during transportation or storage, when the protective material 9b is peeled off from the ceramic green sheet 3, the protective material 9b is made to slide slightly on the ceramic green sheet 1-3. Then, as in the case due to vibrations, etc., as described above, relative displacement occurs, so that a similar dust removal effect can be obtained.

Note that even if the protective material is simply covered, dust may pierce the protective material or fit into the recess and be trapped. Therefore, although displacement is not necessarily required, it is preferable to include displacement in order to remove dust more reliably.

Further, in the protected forest 9b of this embodiment, since the concave portions 9c exist in the form of a mesh, it is only necessary to displace the recesses 9c by the opening diameter of the net.
Therefore, an extremely small amount of displacement is sufficient.

Note that even if the protective material 9b is relatively displaced on the green sheet 3, the protected forest 9b of this embodiment is highly flexible, so that the ceramic green sheet 3 will not be damaged, as will be described later.

Furthermore, since the protective material 9b of this embodiment is in the form of a sheet and is made of a fastened long-fiber nonwoven fabric, it has the advantage that it generates little dust. Moreover, it is highly flexible and easily adheres to the surface of the ceramic green sheet 3.

Therefore, since no gap is formed between the protective material 9b and the ceramic green sheet 3, it is possible to prevent dust from entering there. Moreover, due to close contact, even minute dust can be removed.
can be easily captured.

Furthermore, since it is made of fiber, it has uneven surfaces, which makes it easier to trap dust.

In addition, since the protective material 9b of this embodiment is made of cotton, as in the other embodiments described above, it is difficult to charge the ceramic green sheet 3.

Therefore, it has a dust-proofing effect as well as a dust-removing effect.

Next, a specific experimental example to which this embodiment is applied will be shown.

This experiment was conducted as follows.

First, a large number of ceramic green sheets are divided into two groups, one group is covered with a polyethylene film, and the other group is covered with the protective material 9b of the above embodiment.
The ceramic green sheets were covered with a ceramic green sheet, and then these were peeled off, and the number of dust adhering to the surface of each ceramic green sheet was counted. In Figures 11 and 12,
The results are shown below.

FIG. 11 shows the number of dust particles attached to each green sheet in the conventional product, that is, the case covered with polyethylene film, and FIG. 12 shows the countermeasure product.

That is, in the case of covering with the protected forest 9b of the above-mentioned embodiment, as is clear from a comparison of 1 indicating the number of dust adhering to each green sheet, the former is.

The total average number of adhered dust particles is 7.2, while the total average number of the latter is 2.1.

Therefore, it was demonstrated that dust prevention and dust removal can be effectively achieved by using the protective material of this example.

In the embodiments described above, a nonwoven cotton fabric was used as the protective material, but the present invention is not limited to this.6 For example, a woven cotton fabric or a porous resin sheet may be used. Things like this are possible. In addition, although a ceramic green sheet is shown as an object to be protected, the present invention is
Not limited to this.

It can also be applied to other things, such as high-precision printed circuit boards.

[Effects of the Invention] As explained above, the present invention prevents the generation of static electricity and prevents floating dust from adhering to the electronic circuit board when the protective material covering the electronic circuit board is peeled off. There is an effect that can be done.

Furthermore, the present invention can capture and remove dust, and has the effect of being able to remove dust that is not foreign and has already adhered, such as drilling debris.

Therefore, according to the present invention, it is possible to protect ceramic green sheets used for manufacturing multilayer wiring (boards, etc.) from dust, and to optimally transport and store them.

[Brief explanation of the drawing]

Figures 1 and 2 are points 1 and 2 respectively showing an example of dust prevention during conveyance and storage of ceramic green sheets.
Fig. 3 shows If due to charging in the conventional dust prevention method.
FIG. 4 is an explanatory diagram showing the charging state in the conventional dust prevention method. FIG. 5 is an explanatory diagram showing the operation of the dust prevention method according to an embodiment of the present invention. FIG. Figure 7 is an explanatory diagram showing the state in which debris from drilling etc. is attached to the ceramic green sheet as dust, and Figure 7 shows that the dust attached to coating 1) 7I cannot be removed using conventional dustproofing methods. FIG. 8 is an explanatory diagram showing the dust removal effect according to another embodiment of the present invention, and FIG. 9
Figure (b) is an enlarged plan view showing a part of the protective material;
FIG. 10 is an explanatory diagram showing an example of the manner in which a ceramic green sheet is covered with the protective material of the above embodiment, and FIGS. 11 and 12 are graphs showing the results of a comparative experiment between the above embodiment and a conventional dust prevention method. FIG. 13 is an enlarged sectional view of a main part showing how the protective material captures dust. 1... Receiver is plate, 2... Protective sheet, 3... Ceramic green sheet, 4... Transport box, 5... Guide rail, 9a, 9b... Protective material, 9c... recess, 1
0...Dust.

Claims (8)

[Claims] 1. 1. A dustproof method for an electronic circuit board, which comprises covering a surface of the electronic circuit board that needs to be protected from dust with a protective material made of a material that does not easily charge the electronic circuit board. 2. The surface of the electronic circuit board that needs to be protected from dust is covered with a flexible protective material having a large number of recesses on the surface, and the protective material and the electronic circuit board are relatively displaced to remove dust. A method for removing dust from an electronic circuit board, comprising capturing and removing dust on the surface of the electronic circuit board. 3. The surface of the electronic circuit board that needs to be protected from dust is covered with a protective material that is made of a material that is flexible and does not easily charge the electronic circuit board, and has many recesses on the surface, and the protective material and the electronic circuit are 1. A method for preventing and removing dust from an electronic circuit board, comprising: displacing the substrate relative to the substrate, capturing the dust with the protective material, and removing dust on the surface of the electronic circuit board. 4. A protective material having a large number of concave portions on its surface, and is made of a flexible material that, when covered with an object, adheres closely to the surface of the object and easily captures dust on the object. 5. Made of a material that has many recesses on its surface, is flexible, and when covered with an object, it adheres closely to the surface of the object, easily traps dust on the object, and does not easily charge the object. A protective material characterized by: 6. An electronic circuit characterized in that an electronic circuit board is sandwiched between protective materials that are made of a flexible material that does not easily charge the electronic circuit board and that has a number of recesses on the surface, and is handled during transportation, storage, etc. How to prevent and remove dust from boards. 7. 6. The protective material according to claim 4, wherein the material is a long fiber nonwoven fabric of cotton. 8. The dust removal method according to claim 2, or the dust prevention and dust removal method according to claim 3 or 6, wherein the protective material is a long fiber nonwoven fabric.