JP2005034972A - Dry abrasive and dry polishing device using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the replacement frequency without causing deterioration in polishing effect even after a long-time use in an insulating sheet layer and a protective sheet formed on the surface of a metal bump forming side of a metal foil in which a metal bump is selectively formed on one surface and an abrasive for polishing the metal bump until the top of the metal bump is exposed. <P>SOLUTION: A mixture of abrasive powder 8 and an adhesive 10 comprising a hard powder is applied onto at least one surface of a flat base 4 having rigidity, and the dried and cured surface forms a flat abrasive layer 6. A material formed by impregnating a fabric with a resin and curing the fabric is preferably used as a base 2, and carborundum or diamond powder is preferably used as the abrasive powder 8. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention provides a dry abrasive, for example, after forming an insulating layer and a protective sheet made of resin on the surface of the metal bump forming side of a metal foil in which metal bumps are selectively formed on one surface. The present invention relates to a dry abrasive suitable for polishing an insulating layer, a protective sheet, and the metal bump until the top surface of the metal bump is exposed, and a dry polishing apparatus using the dry abrasive.

  The applicant company uses a metal bump, for example, a copper bump formed on one surface of a metal foil, for example, a copper foil as an interlayer connecting means, and the metal foil, for example, a copper bump of the copper foil, for example, an interlayer on the copper bump forming surface. An insulating film is formed so as to be penetrated by the metal bump, another metal foil such as a copper foil is formed on the surface of the interlayer insulating film, and the metal foil such as a copper foil on both sides of the interlayer insulating film is selected. For example, Japanese Patent Application No. 11-289277, Japanese Patent Application No. 2000-142658, etc. Various proposals were made.

4A to 4E are cross-sectional views showing an example of a method of manufacturing a wiring board using such metal bumps, for example, copper bumps, as interlayer connection means in the order of steps.
(A) First, a metal plate 100 having a three-layer structure is prepared. The metal plate 100 includes a first copper foil 102 having a thickness of approximately 13 μm and a second copper foil 104 having a thickness of 30 to 160 μm, and a nickel foil 106 having a thickness of 0.1 to 2 μm serving as an etching barrier. Are stacked.
Then, a resist film 108 serving as a bump forming etching mask is selectively formed on the surface of the second copper foil 104. FIG. 4A shows a state after the resist film 108 is formed.

(B) Next, as shown in FIG. 4B, by using the resist film 108 as a mask, the second copper foil 104 is etched to form a bump 110 for correlation connection made of copper. In this etching, the nickel foil 106 serves as an etching barrier and prevents the first copper foil 102 from being etched.
(C) Next, the resist film 108 is removed, and then the nickel foil 106 is etched using the bumps 110 as a mask. FIG. 4C shows the state after the etching removal.

(D) Next, as shown in FIG. 4D, the insulating sheet 112 and the substantially sheet 114 to be an interlayer insulating film are made to face the surface on the bump 110 forming side of the metal plate 100. The insulating sheet 112 is made of, for example, polyimide, liquid crystal polymer, or BCB film.
The protective sheet 114 does not form a part of the wiring board, but is formed to protect the surface of the metal plate 100 in the subsequent pressurizing and heating laminating process, and is removed when the laminating process is completed. .

(E) Next, the insulating sheet 112 and the protective sheet 114 are laminated on the surface of the metal plate 100 on the bump 110 formation side by pressing and heating through a cushion material (not shown). FIG. 4E shows a state after the lamination.
(F) Next, the surface of the metal plate 100 on which the insulating sheet 112 and the protective sheet 114 are formed is polished until the surface of the bump 110 is exposed. FIG. 4F shows the state after the polishing.

(G) Next, the protective sheet 114 is peeled off, and then, as shown in FIG. 4 (G), a third copper foil (thickness) is formed on the surface where the protective sheet 112 is laminated and the top surface of the bump 110 is exposed. (Several μm to several tens μm) 116 is exposed.
Then, the copper foil 116 is laminated by pressing.
After that, the first copper foil 102 and the third copper foil 116 are patterned by selective etching to form wiring films, and the wiring films are interlayer-connected by the bumps 110.

In the wiring board manufacturing technique shown in FIG. 4, the polishing step (F) is indispensable, but the polishing must be performed by a dry polishing method. That is, when a wet (wet) polishing method is used, moisture may enter between the insulating sheet 112 and the bump 110, and the moisture deteriorates the bump 11 and the insulating sheet 112, resulting in poor insulation and poor connection. This is because it may occur.
As described above, the polishing step (F) was performed by a dry polishing method, and specifically, the following various dry polishing methods were used. 5 (1) to (3) are cross-sectional views showing special abrasives used in the various dry polishing methods.

(1) Polishing method with sandpaper Sandpaper is a powder of carbon random or the like mixed with an adhesive, applied to paper or cloth and dried, and the surface is as shown in Fig. 5 (1). Yes.
(2) Polishing Method Using Ceramic A ceramic polishing material is obtained by mixing a powder of alumina or the like with an adhesive and then sintering it, and is porous as shown in FIG. 5 (2).

(3) Polishing method by buff Abrasive grains are bonded to fibers and the like, and has a cross-sectional structure as shown in FIG. A polishing machine in which the fibers to which the abrasive grains are bonded is bundled into a cylindrical shape, the cylindrical buff is rotated, and an object to be polished is applied to the rotating buff for polishing is often used for polishing. .
Incidentally, there are actually few types of polishing machines that can perform dry polishing, whereas there are many types of polishing machines that perform wet polishing.
JP 2001-1111189 A Japanese Patent Laid-Open No. 2001-326459

By the way, each of the above-described conventional dry polishing methods performed in the polishing step (F) has a problem.
(1) Problem of polishing method using sandpaper As described above, the surface of sandpaper has irregularities on the surface as shown in FIG. 5 (1). It was easy to clog, the polishing effect was reduced immediately, and it was necessary to change the sandpaper frequently. This is a problem that cannot be overlooked because the cost required to purchase sandpaper and the cost due to loss of time required for replacement become factors that increase the manufacturing cost.
Also, since sandpaper is not rigid, when polished, it is bent in a concave shape as shown in FIG. 6, and it is difficult to polish with uniform polishing force, and there is a tendency that the polishing force for the bumps in the center is insufficient. There is a problem that it is difficult to perform good polishing on the central bump. Also, the effect of polishing differs between densely packed bumps and sparse parts that are not densely packed. Bumps in densely packed parts are sufficiently polished, but bumps in sparse parts are often not polished sufficiently. there were.

(2) Problem of polishing method with ceramic As described above, the polishing material with ceramic is porous as shown in FIG. 5 (2) and has a large number of recesses on its surface. Because of the dry type, the copper powder is easily clogged in the concave portion, and the polishing effect is immediately reduced. This is the same problem as sandpaper, and it cannot be overlooked.
However, in the case of ceramic, there is an advantage that the polishing power can be recovered by dressing. However, there is a problem that the lifespan is considerably shortened by dressing.

(3) Problem of polishing method with buff As shown in FIG. 5 (3), the buff has a convex portion on the surface where the abrasive grains are formed, and a concave portion where the surface is not formed. . Therefore, the problem that copper powder is clogged in the recessed portion is unavoidable, and has the same problem as the polishing method using sandpaper or ceramic. Further, there is a problem that the abrasive grains are easily peeled off.
However, the buff has the advantage that the polishing power can be recovered by dressing, as in the case of ceramic, but there is a problem that the life is considerably shortened by dressing.

  The present invention has been made to solve such problems, and as a dry abrasive, it is possible to provide a dry abrasive with little deterioration in the polishing effect even when used for a long time, and less frequent replacement. An object of the present invention is to provide a polishing apparatus free from burrs.

The dry abrasive of claim 1 has a surface obtained by applying a mixture of abrasive powder made of hard powder and an adhesive to at least one surface of a rigid flat base, and drying and curing the surface. A flat polishing layer is formed.
The dry abrasive according to claim 2 is the dry abrasive according to claim 1, wherein the base is formed by impregnating a resin into a cloth and curing.
The dry abrasive according to claim 3 is the dry abrasive according to claim 1 or 2, wherein the abrasive powder is made of carbon random or diamond powder.

According to a fourth aspect of the present invention, there is provided a dry polishing apparatus comprising a dry polishing material having a polishing surface on a plane that pressurizes an object to be polished conveyed in a fixed direction with a predetermined pressure from above with the surface to be polished facing upward. The length of the abrasive in the direction orthogonal to the transport direction is longer than the length of the object to be polished in the direction orthogonal to the transport direction, and during polishing, the abrasive moves circularly while maintaining the pressurized state. It is characterized by being made.
The dry polishing apparatus according to claim 5 is the dry polishing apparatus according to claim 4, wherein the dry abrasive is provided on at least one surface of a rigid plate-like base with polishing powder and adhesive made of hard powder. It is characterized in that it is formed by applying a mixture of the above and drying and curing to form a flat polishing layer.

According to the dry abrasive of the present invention, since the surface of the polishing layer formed on the surface of the flat plate base having rigidity is flat, the surface is basically clogged with metal powder such as copper or powder such as resin. There is no recess.
The polishing force can be obtained by brushing the surface of the polishing layer to cause the polishing powder to protrude. However, the surface of the polishing layer can be uneven by this, but the recess is extremely shallow, there is no risk of clogging with metal powder such as copper or resin powder, and even if metal powder adheres to the surface, Easy to wash off.
Therefore, even if the polishing with the dry abrasive is continued, the decrease in the polishing effect is small, and the replacement frequency can be significantly reduced as compared with the conventional case.

Further, since the base is rigid, the dry abrasive does not bend during polishing and remains flat. Therefore, it is possible to uniformly apply pressure to each bump and perform uniform polishing.
Because of such rigidity, the applied pressure is uniform between the portion where the bump formation density is high and the portion where the bump density is low, and polishing can be performed uniformly on all the bumps.

According to the dry polishing apparatus of the present invention, the dry polishing material is circularly moved with pressure applied to the object to be polished conveyed in a certain direction, so that there are protrusions such as bumps on the surface to be polished. It is possible to polish the protrusions so that no burrs are generated.
If the dry abrasive of the present invention is used as the dry abrasive, the above-mentioned advantages of the dry abrasive of the present invention can be enjoyed as a dry polishing apparatus.

Basically, the base of the dry abrasive of the present invention is preferably one in which a cloth is impregnated with a resin and cured to have rigidity. The polishing powder in the polishing layer formed on the surface of the base is preferably carbon random or diamond powder.
And as a dry-type polishing apparatus, the conveyance mechanism which conveys the to-be-polished body (for example, three-layer metal plate) which has a fine projection (bump) on the surface to be polished in the state where the surface to be polished is upward. Further, a polishing mechanism is preferably provided on the upper side thereof, which is provided with a polishing mechanism that makes a circular motion while pressing a material to be polished with a polishing surface facing downward to the object to be polished with a predetermined pressure. As the dry abrasive, it is preferable that the base is impregnated with a resin and cured to have rigidity, and the abrasive powder in the polishing layer formed on the surface of the base is carbon random, or Diamond powder is preferred.

Hereinafter, the present invention will be described in detail according to illustrated embodiments.
1A to 1D are cross-sectional views showing a first embodiment of the dry abrasive of the present invention. FIG. 1A shows a dry abrasive before dressing, and FIG. 1B shows a dry abrasive after dressing. (C) is an enlarged view of the surface of the dry abrasive before dressing, and (D) is an enlarged view of the dry abrasive after dressing.

  In the figure, 2 is a dry abrasive, and 4 is a thin flat plate-like base of the dry abrasive 2. For example, a cloth is impregnated with a resin and cured to give rigidity. Reference numeral 6 denotes a polishing layer formed on one main surface of the base 4, and a mixture of abrasive powder (abrasive) 8 such as carbon random or diamond powder mixed with an adhesive 10 is applied to the main surface of the base 4. The layer surface 12 is applied so as to be flat, dried and cured.

In the dry abrasive 2 as manufactured, the layer surface 12 is flat as shown in FIGS. 1 (A) and 1 (C). In this state, the polishing powder (abrasive) 8 does not protrude, so the polishing effect cannot be said to be sufficient.
Therefore, the surface of the polishing layer 6 is dressed with, for example, sandpaper. Then, since the adhesive 10 is shaved thinly, as shown in FIGS. 1B and 1C, the polishing powder (abrasive) 8 on the outermost surface portion of the layer protrudes and has a sufficient polishing effect. Moreover, only the first dressing is required.

Therefore, as shown in FIG. 2, the polishing shown in FIG. 4F is performed on the metal plate 100 by the polishing apparatus using the dry abrasive 2 that has been dressed. Such polishing is performed on the metal plate 100 in a state where the insulating sheet 112 and the protective sheet 114 are laminated as shown in FIG.
Specifically, the polishing of the metal plate 100 using the dry abrasive 2 is performed by applying the surface of the polishing layer 6 of the dry abrasive 2 to the bump 110, insulating sheet 112, and protective sheet 114 forming surface of the metal plate 100. And pressing with a uniform force, and moving the dry abrasive 2 relative to the metal plate 100 in this state. Specifically, the metal plate 100 is transported in one direction as shown by an arrow b with the surface to be polished facing upward by a transport mechanism (not shown), and the dry abrasive 2 is applied by a drive mechanism (not shown). While maintaining the pressure state, circular movement is performed as indicated by an arrow a.

Then, since the dry abrasive 2 has rigidity, as shown in FIG. 3, the dry abrasive 2 maintains a flat state without being bent during polishing. Therefore, it is possible to uniformly press the bumps 110 and perform uniform polishing.
Conventionally, there is a problem that the applied pressure is non-uniform between the portion where the formation density of the bump 110 is high and the portion where the bump 110 is low. However, according to the dry abrasive 2, the bump 110 has rigidity. The applied pressure is uniform between the portion where the formation density is high and the portion where the formation density is low, and polishing can be performed uniformly on all the bumps 110.

Further, the surface of the polishing layer 6 is basically flat, and the polishing powder 8 merely protrudes due to dressing, so that no recesses that cause copper powder clogging are formed. Therefore, even if the polishing with the dry abrasive 2 is continued, the reduction of the polishing effect is small, and the replacement frequency can be remarkably reduced as compared with the conventional case.
However, although copper powder or the like may adhere to the surface of the polishing layer 6, it does not stick to the concave portion, that is, does not stick, so that the copper powder or the like can be removed by washing the surface with water or the like.

  Then, since the dry abrasive 2 is circularly moved as indicated by the arrow a while maintaining the pressurized state, the polishing can be performed so that each bump 110 is not burred. That is, according to the method in which the dry polishing material 2 is not moved and the metal plate 100 that is an object to be etched is polished while being conveyed in a certain direction (arrow b), each bump 110 is moved in the direction opposite to the conveying direction. There is a risk that extended burrs may occur. However, when the dry abrasive 2 is caused to perform a circular motion as indicated by an arrow a, it is possible to polish without fear of such burrs.

The present invention provides an insulating sheet and protective sheet made of a resin, which is formed on a surface of the metal foil on which a metal bump is selectively formed on one surface, and the metal bump. It is suitable for an abrasive that polishes until the top surface of the metal bump is exposed.
However, the applicability of the present invention is not necessarily limited thereto, and can be applied to general abrasives that are dry-polished flat.

(A)-(D) is sectional drawing which shows 1st Example of this invention dry abrasive, (A) shows the dry abrasive before dressing, (B) shows the dry abrasive after dressing. , (C) shows an enlarged surface portion of the dry abrasive before brushing, and (D) shows an enlarged dry abrasive after dressing. It is a perspective view which shows the state grind | polished with respect to a metal plate using the dry-type abrasive | polishing material which dressed. It is sectional drawing which shows the technical effect at the time of using the dry-type abrasive | polishing material shown in FIG. (A)-(G) is sectional drawing which shows an example of the manufacturing method of the wiring board which used the copper bump as an interlayer connection means in order of a process, and shows the technical background in which grinding | polishing by this invention dry abrasive is performed. (1)-(3) is sectional drawing which shows another prior art example of the dry-type abrasive | polishing material used for grinding | polishing. It is sectional drawing which shows one of the problems at the time of using the conventional dry-type abrasive | polishing material.

Explanation of symbols

2 ... Dry abrasive, 4 ... Base, 6 ... Abrasive layer, 8 ... Abrasive powder (abrasive), 10 ... Adhesive, 12 ... Layer surface (surface of abrasive layer) ),
100: object to be polished (metal plate).

Claims (5)

Apply a mixture of abrasive powder made of hard powder and adhesive to at least one surface of a rigid flat base, and dry and harden the surface to form a flat polishing layer A dry abrasive characterized by that. The dry abrasive according to claim 1, wherein the base is formed by impregnating a cloth with a resin and curing. The dry polishing material according to claim 1 or 2, wherein the polishing powder is made of carbon random or diamond powder. A dry abrasive having a polishing surface on a plane that pressurizes the object to be polished, which is conveyed in a certain direction with the surface to be polished upward, from above with a predetermined pressure,
The dry abrasive has a length in a direction orthogonal to the transport direction that is longer than a length in a direction orthogonal to the transport direction of the object to be polished, and during polishing, circular motion while maintaining the pressurized state A dry polishing apparatus characterized by comprising: The above dry abrasive is coated with a mixture of abrasive powder made of hard powder and an adhesive on at least one surface of a rigid flat base, and then dried and hardened to make a flat surface. The dry polishing apparatus according to claim 4, wherein a layer is formed.

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