JPH0365676B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to a multilayer ceramic substrate for mounting electronic components, and particularly to a multilayer ceramic substrate with improved through-hole shapes. [Prior Art] Multilayer ceramic substrates on which electronic components are mounted are described in many documents (for example, "Electronic Technology" Vol. 23,
14, pages 96-100), it is manufactured by a sheet lamination method. FIGS. 1A to 1C show part of a process for manufacturing a multilayer ceramic substrate using a conventional sheet lamination method. First, a process A in which through-holes are punched out using a mold in a ceramic green sheet (hereinafter simply referred to as "sheet") 1 created by a known doctor blade method. here,
Conventionally, the diameter of punch 2 was 160 μm and the diameter of die 3 was
When the punch-die diameter difference was set to about 20 μm, such as 180 μm, the hole diameters on the upper and lower sides of the sheet 1 were both aligned with the die shape, and a cylindrical through hole 4 with a hole shape D of 180 μm was obtained. Next, the through-holes 4 are filled with a conductor using conductive paste in the perforated sheet 1,
Following this, a conductor pattern wiring (hereinafter simply referred to as "wiring") 5 is printed using a conductive paste having a composition different from that of the conductive paste. At this time, the conductor spacing S between the wiring 5 and the upper surface 6 of the conductor 4' in the through hole 4 was designed to be 60 μm in order to prevent shorts from occurring due to the printing variations. Further, in this process, many defects in filling the through holes 4 occurred, which was a problem. Hole filling failure is a phenomenon in which the conductive paste does not completely spread to the bottom of the through hole 4, leaving a cavity 8. If this occurs, cracks may occur in the board during sintering of the sheet 1, or cracks may occur inside the through hole 4. Since the conductor of the sheet 1 may be disconnected, the appearance of the sheet 1 after printing is inspected to remove defective sheets. The next step is lamination of sheets 1 (C). In this process, the inspected sheet 1 is aligned using guide pins, etc., but in reality, misalignment may occur, and in this case, the conductor 4' in the through hole 4 of the upper sheet A defect occurs in which the lower surface 7 and the wiring 5 of the lower sheet are shot. This is because the positioning accuracy a of the sheets in the laminate shown in Figure 1C is about 15 μm, so the conductor spacing S' between the through hole and the wiring when stacked is about 45 μm, and the same sheet The cause of this failure was that the conductor spacing S within the circuit was reduced to 3/4, but since this failure could not be detected by visual inspection, it reduced the manufacturing yield of multilayer ceramic substrates and became a serious problem. . [Object of the Invention] The present invention has been made in view of the above-mentioned circumstances, and its purpose is to solve the above-mentioned problems in conventional multilayer ceramic substrates, and to solve problems such as poor filling of the through holes and during lamination. An object of the present invention is to provide a multilayer ceramic substrate that can prevent a decrease in manufacturing yield due to shot failure caused by positional deviation of the substrate. [Summary of the Invention] The above-mentioned object of the present invention is to form a hole in a ceramic green sheet, fill the hole with conductive paste, print necessary wiring, and then laminate a plurality of sheets. This is achieved by a multilayer ceramic substrate produced by sintering, wherein the holes provided in the sheet are holes with a diameter difference of approximately 30 μm between the top and bottom after sintering. . [Embodiments of the Invention] Hereinafter, embodiments of the present invention will be described in detail based on the drawings. 2A to 2C show a part of the manufacturing process of a multilayer ceramic substrate according to an embodiment of the present invention, and correspond to the above-mentioned FIGS. 1A to 1C. First, in step A, punching of through holes is performed on the sheet 1. The important thing here is, for example, punch 2
For example, the diameter of die 3 is 140 μm, and the diameter of die 3 is 180 μm.
The punch diameter is made smaller than before, and the difference between the punch and die diameters is increased to approximately 40 μm. As a result, the shape of the obtained through hole 4A becomes approximately a truncated cone shape, and the sheet 1
The upper pore diameter d was 150 μm, and the lower pore diameter D was 180 μm. Next, with the side of the perforated sheet 1 with the larger hole facing up, the conductor filling of the through holes 4A with conductive paste and the formation of the wiring 5 by printing are performed by a normal method B. At this time, the upper surface 6A of the conductor 4A in the wiring 5 and the through hole 4A
The designed conductor spacing S between the
shall be. In the above conductor filling process, the through holes 4A have a widened upper part, which has the effect of allowing conductor filling to be performed more smoothly than in the past, preventing defects in hole filling, and greatly increasing the yield of sheets after printing. was able to improve. The next step is lamination of sheets 1 (C). The positional deviation a of the sheet 1 that occurs in this process is 15 μm due to the alignment using the guide pins etc.
It will be about. However, sheet 1 of this example
The hole diameter of through hole 4A is 30 μm on the upper and lower sides.
Due to the difference in degree, even if the positional deviation a is about 15 μm, the conductor spacing S between the upper surface 6A of the conductor 4A′ in the through hole 4A and the wiring 5 is the designed value of 60 μm.
is ensured. As a result, shot failures during lamination were significantly reduced, and the manufacturing yield of multilayer ceramic substrates was significantly improved. An example of specific experimental results in this example is as follows:
Shown in Table 1. Table 1 shows an example when the diameter of the punch 2 is 140 μm, as described above.
This is an example showing the results of creating a ceramic multilayer substrate made by laminating 18 mm square sheets. Here, the number of through holes is 20,000, and the total length of wiring between the through holes is approximately 200 m. In addition, as a conventional example,
The ones that correspond to a die diameter of 165 μm are listed. The results shown in Table 1 were obtained by making five samples each using the method described above, and performing a 100% inspection to evaluate the performance for filling defects and shot defects.

【table】

〔Effect of the invention〕

As described above, according to the present invention, holes are formed in ceramic green sheets, the holes are filled with conductive paste, and necessary wiring is printed, and then a plurality of sheets are laminated and sintered. In the multilayer ceramic substrate created by
Since the hole is 30 μm in size, it is possible to prevent shot failure due to poor filling of the conductive paste and positional deviation during lamination, and this has the effect of significantly improving manufacturing yield.

[Brief explanation of drawings]

1A to 1C are diagrams showing a part of the manufacturing process of a conventional multilayer ceramic substrate, and FIGS. 2A to 2C are diagrams showing a part of the manufacturing process of a multilayer ceramic substrate according to an embodiment of the present invention. FIGS. 3A and 3B are diagrams showing essential parts of another embodiment of the present invention. 1: sheet, 2: punch, 3: die, 4,
4': Through hole, 4A, 4A': Conductor in through hole, 5: Wiring, 6, 6A: Top surface of conductor,
7, 7A: Bottom surface of conductor.

Claims (1)

[Claims] 1. A multilayer ceramic substrate created by drilling holes in a ceramic green sheet, filling the holes with conductive paste, and printing the necessary wiring, then stacking and sintering a plurality of sheets. A multilayer ceramic substrate characterized in that the holes provided in the sheet have a diameter difference of approximately 30 μm between the upper and lower holes after sintering.