JP2006165358A - Manufacturing method of ceramic sintered substrate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology capable of decreasing damages caused to a substrate itself with a reduced number of steps at a low cost when the surface of a ceramic multilayer sintered substrate with a conductor is made flat and a thin film pad is formed on the surface. <P>SOLUTION: The ceramic substrate is manufactured by adhering a polyimide sheet to the ceramic sintered substrate, forming a via to a through-hole of the polyimide sheet, applying electric plating to the via, and polishing both the polyimide sheet and the thin film via pad at the same time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to planarization and thin film pad formation of a ceramic multilayer sintered substrate having conductors.

  An example of a conventional method for flattening the surface of a ceramic multilayer sintered substrate having a conductor and forming a thin film pad will be described with reference to FIG. In the conventional example, the surface of the ceramic multilayer sintered substrate 1 is directly polished and flattened (step 2), and then a thin film pad 3 is formed (step 3). FIG. 2 shows another example of the conventional example. After forming the plating guide resist 5 on the surface conductor pad of the ceramic multilayer sintered substrate 1 (step 2) and forming the thin film via 6 (step 4), for example, organic insulation such as PIQ of Hitachi Chemical Co., Ltd. The film 7 was repeatedly applied and cured and baked by spin coating (step 5), and the surface thereof was polished by tape and flattened (step 6). This type of technique is disclosed in, for example, Japanese Patent Application Laid-Open No. 7-235774.

JP-A-7-235774

  Among the above prior arts, the former method has a problem that microcracks are generated on the ceramic surface because the substrate surface is directly polished. On the other hand, the latter has a problem that the coating film thickness is limited to about 10 μm because it is applied by the spin coating method, and the process becomes longer and the cost becomes higher because of repeated coating. An object of the present invention is to provide a technique capable of reducing damage to a substrate when the surface of a ceramic multilayer sintered substrate having conductors is manufactured and a thin film pad is formed by flattening the substrate. Furthermore, it aims at providing the technique which reduces the damage given to a board | substrate and shortens a process.

  In order to achieve the above object, in the present invention, the surface of a ceramic multilayer sintered substrate having conductors and the formation of a thin film pad are simultaneously polished on a polyimide sheet affixed to the substrate surface and a thin film via pad formed by electroplating. To do.

  Since the polyimide sheet and thin film via pad attached to the substrate surface are polished, planarization is possible without damaging the substrate itself. Further, since the thickness of the polyimide sheet is affixed at a time in accordance with the amount of warpage of the substrate, the process can be shortened and the cost can be reduced.

  An example in which surface flattening and thin film pad formation of a ceramic multilayer sintered substrate having conductors is realized in a short process and at low cost is shown below.

  First, a method for manufacturing a ceramic multilayer sintered substrate obtained by polishing a polyimide sheet attached to the substrate surface for flattening the surface of the ceramic multilayer sintered substrate having conductors and forming a thin film pad will be described. FIG. 3 shows sectional views of the substrate obtained when this manufacturing method is executed in the order of steps. In FIG. 3, 1 is a ceramic multilayer sintered substrate, 2 is a conductor, 4 is a conductor pad, 9 is a polyimide sheet, 10 is a barrier metal, 6 is a plating via, and 13 is an electrode film for via.

  In the method for producing a ceramic multilayer sintered substrate of this embodiment, first, a polyimide sheet 9 having a thickness equal to or greater than the warpage amount of the substrate surface is attached to the surface of the ceramic multilayer sintered substrate (step 2). As the polyimide sheet, for example, Upilex S manufactured by Ube Industries, Ltd. can be used.

  Next, a barrier metal 10 for through-hole processing for forming the through-hole 12 with a laser is formed in the polyimide sheet 9 (step 3). Here, a Cu film formed by sputtering is used as the barrier metal for through-hole processing. Also, the barrier metal for through-hole processing is patterned using photolithography technology. This through-hole processing barrier metal is removed by polishing at the time of flattening in a subsequent process, and thus is not subjected to processing such as etching.

  Next, the substrate on which the barrier metal 10 is formed is irradiated with laser to form the through hole 12 (step 4). At this time, excimer, YAG, or CO2 laser is used as the type of laser. The laser beam 11 strikes only the surface of the polyimide sheet 9 where the through-hole processing barrier metal 10 is not provided, whereby the through-hole 12 is formed. Since the barrier metal 10 for through-hole processing is patterned by the photolithographic technique as described above, the size and position accuracy of the through-hole 12 can be made high.

  Next, a plating via electrode film 13 is formed on the back surface of the substrate, and a plating via 6 is grown by electroplating (step 5). At this time, the plating film thickness is formed to be larger than the substrate surface warpage amount. Since it is polished in a subsequent process, if it is formed more than the amount of warpage of the substrate surface, it does not require much accuracy without problems.

  Next, the plating via electrode film 13 is removed, and finally, the polyimide sheet 9, the through-hole processing barrier metal 10, and the plating via 6 are simultaneously lapped until flat (step 6). By this polishing, planarization and thin film via pad formation are completed simultaneously.

  Furthermore, a multi-chip module is manufactured by mounting a chip component such as an IC on a via pad of a ceramic substrate manufactured by the above method.

Example 1 shows an example of a method for manufacturing a ceramic substrate in which a plating via electrode film formed on the back surface of the substrate is formed on the substrate surface (upper surface). This method is effective when the conductor forming the thin film via pad is not electrically connected to the back surface of the substrate. FIG. 4 shows a cross-sectional view of a substrate obtained when this manufacturing method is executed in the order of steps. Steps 1 to 4 are formed by the same process as in the first embodiment.
In step 5, a plating via electrode film 13 is formed on the substrate surface (upper surface), and a plating via 6 is grown on the entire surface of the substrate (upper surface) by electroplating. The plating film thickness at this time is also formed so as to be equal to or greater than the substrate surface warpage amount as in the first embodiment. Since it is polished in a later process, it is not necessary to form it with high accuracy. Further, the plating via electrode film 13 on the through-hole processing barrier metal 10 is removed by polishing at the time of flattening, so that a treatment such as etching is unnecessary. Finally, the plating via 6, the plating via electrode film 13, the through-hole processing barrier metal 10, and the polyimide sheet 9 are lapped together until flat. By this polishing, planarization and thin film via pad formation are completed simultaneously.

The figure explaining the prior art example which forms the thin film pad, after grind | polishing and planarizing the board | substrate surface directly for the curvature of a ceramic multilayer sintered board. The figure explaining the prior art example which forms the thin film via on the conductor pad, and coats and cures the organic insulating film more than the amount of warp, and polishes and flattens the warp of the ceramic multilayer sintered substrate. The figure explaining the example which planarizes the curvature of a ceramic multilayer sintered board by grind | polishing the polyimide sheet and thin film via pad which were affixed on the board | substrate surface. The figure explaining the example which planarizes the curvature of the ceramic multilayer sintered substrate by polishing the polyimide sheet affixed to the substrate surface and the thin film via pad, and forms the electrode film for the plating via on the upper surface of the substrate .

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Ceramic multilayer sintered board, 2 ... Conductor, 3 ... Thin film pad, 4 ... Conductor pad, 5 ... Plating guide resist, 6 ... Plating via, 7 ... Organic insulating film, 8 ... Thin film via pad, 9 ... Polyimide sheet, 10 ... barrier metal for through-hole processing, 11 ... laser light, 12 ... through-hole, 13 ... plating electrode film.

Claims (4)

In the method of manufacturing a ceramic substrate,
A polyimide sheet is attached to a ceramic sintered substrate with conductors applied.
Forming a plating via in the through hole of the polyimide sheet;
A method for producing a ceramic substrate, comprising performing planarization by polishing both the polyimide sheet and the plating via.   The method for manufacturing a ceramic substrate according to claim 1, wherein the polyimide sheet is affixed with a sheet thicker than a warp width of the ceramic sintered substrate.   2. The ceramic substrate according to claim 1, wherein the through hole is formed by irradiating a laser beam after forming a barrier metal on the polyimide sheet by sputtering a copper film and patterning using a photolithographic technique. Production method. A polyimide sheet is attached to a ceramic sintered substrate with conductors applied.
Forming a plating via in the through hole of the polyimide sheet;
A multi-chip module manufactured by mounting an integrated circuit on a ceramic substrate manufactured by performing a planarization process by polishing both the polyimide sheet and the plating via.

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