JP2000031333A - Surface mount ceramics substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a surface mount ceramics substrate from breaking by reducing a stress caused by the deflection of a mother board, etc., wherein a large surface mount ceramics substrate, for example the length of a side of one a square main surface being 10 mm or longer, is connected to a conductive land on a mother board through a plurality of external connection terminals of area array structure provided on the main surface. SOLUTION: All external connection terminals 15 are provided in a square terminal allocation region 17 with margins m1 and m2 of width 1 mm or wider left at the peripheral part of a main surface 14, and if at least the length L1 of a longitudinal side 12 of the main surface 14 or the length L2 of a lateral side 13 is 14 mm or longer, lengths a1 and a2 of sides 18 and 19 of the terminal allocation 17 extending parallel to the sides 12 and 13 of 14 mm or longer are set 12 mm or shorter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface mount type ceramic substrate, and more particularly, to a surface mount type ceramic substrate having an external connection terminal having an area array structure.

[0002]

2. Description of the Related Art A surface mount type ceramic substrate which is of interest to the present invention is used for surface mounting on a motherboard such as a printed circuit board, and structurally, a ceramic layer provided therein has a multilayer structure. Some have a single-layer structure, and some functionally constitute a PA module substrate, a VCO substrate, an RF diode switch, an IC package, various modules, a ceramic package, and the like.

[0003] Such a surface mount type ceramic substrate is
A plurality of external connection terminals are provided, and the external connection terminals are connected to conductive lands on the motherboard via these external connection terminals, so that they are surface-mounted on the motherboard.

[0004] The surface mounting type ceramic substrate typically has a configuration shown in FIG.
And the one shown in FIG.

The surface mount type ceramic substrate 1 shown in FIG.
In (2), as shown in a plan view in (1) and a side view in (2), a plurality of external connection terminals 2 are present from the side surface 3 of the substrate 1 to a part of each of the main surfaces 4 and 5. It is provided in.

On the other hand, in the surface mount type ceramic substrate 6 shown in a plan view in FIG.
It is provided on one main surface 8 of the substrate 6. Such an arrangement structure of the external connection terminals 7 is called an area array structure, and more specifically, an LGA (Land Grid A).
ray) or BGA (Ball Grid Arra)
There is an arrangement structure as in y). In the external connection terminal 7 having such an area array structure, a margin m having a width of about 0.1 mm to 0.5 mm is generally provided at a peripheral portion of the main surface 8.
It is arranged so as to leave 1 and m2.

[0007]

In any of such surface mount type ceramic substrates 1 and 6, at least one of the vertical side and the horizontal side defining the main surface 4, 5 or 8 has a length of 10 mm or more. The longer the length, the more the stress exerted on the surface-mounted ceramic substrate 1 or 6 due to bending, thermal shock, dropping, vibration, etc. of the motherboard in the state of being mounted on the motherboard. And the surface mounting type ceramic substrate 1 or 6 is broken, or the external connection terminal 2 or 7
Peeling is more likely to occur. In particular, regarding the bending of the motherboard, for example, when a printed circuit board having a plane size of 100 mm × 40 mm and a thickness of 1.6 mm is used as the motherboard, if the bending of the printed circuit board is 1.5 mm or less, the surface is Although it is required that the mounting type ceramic substrate 1 or 6 is not broken, at least one of the vertical side and the horizontal side is 10 m as described above.
In the case of having a length of not less than m, even a bending of about 1.0 mm may be broken.

For this reason, in the conventional surface mount type ceramic substrate 1 or 6, it is difficult to make at least one of the vertical side and the horizontal side to be 10 mm or more in length.

Therefore, an object of the present invention is to have a rectangular main surface defined by a vertical side and a horizontal side, and at least one of the vertical side and the horizontal side of the main surface has a length of 10 mm or more. An object of the present invention is to solve the above-mentioned problem in a surface mount type ceramic substrate.

[0010]

The present invention has a quadrangular main surface defined by a vertical side and a horizontal side, and at least one of the vertical side and the horizontal side has a length of 10 mm or more. A plurality of external connection terminals having an area array structure are provided on the surface, and the external connection terminals are connected to conductive lands on the motherboard via these external connection terminals, so that the surface mounting type ceramic substrate is mounted on the motherboard. A first embodiment applied when at least one of the vertical side and the horizontal side of the main surface has a length of 14 mm or more, and a case where the length is less than 14 mm. There is a second embodiment applied to the second embodiment.

In the first embodiment, in order to solve the above-mentioned technical problem, all the external connection terminals are provided in a square terminal arrangement region which leaves a margin of 1 mm or more in the peripheral portion of the main surface. A side of the terminal arrangement region, which extends in parallel with at least one of the vertical side and the horizontal side of the main surface and has a length of 14 mm or more, has a length of 12 mm or less.

The second embodiment is characterized in that all of the external connection terminals are provided in a square terminal arrangement region which leaves a margin of 1 mm or more in width at the periphery of the main surface.

[0013] In the present invention, it is preferable that at least one via hole connection portion connected to at least one of the external connection terminals is formed inside.

The present invention is particularly advantageously applied when the surface mount type ceramic substrate includes a low-temperature sintered ceramic.

The surface mount type ceramic substrate according to the present invention may have a multilayer structure or a single layer structure.

[0016]

FIG. 1 is a plan view showing a surface mount type ceramic substrate 11 according to a first embodiment of the present invention.

Referring to FIG. 1, surface-mount type ceramic substrate 11 has a quadrangular shape, more specifically, a square main surface 14 defined by a vertical side 12 and a horizontal side 13;
The length L1 of the vertical side 12 and the length L2 of the horizontal side 13 are both 10 mm or more.

On the main surface 14, a plurality of external connection terminals 15 having an area array structure such as LGA or BGA are provided. The surface mount type ceramic substrate 11 is connected to conductive lands on the motherboard (not shown) via the external connection terminals 15 so as to be surface mounted on the motherboard.

The external connection terminal 15 is, for example, A
When a conductive film containing at least one metal selected from g, Pd, Pt, Cu, Ni, W and Au is formed, and such a conductive film is formed by baking a conductive paste, The conductive paste may be applied when the ceramic substrate 11 is in a raw state, and the conductive paste may be fired simultaneously with the firing of the ceramic substrate 11, or the conductive paste may be applied after the ceramic substrate 11 is fired. Then, this may be fired.

In FIG. 1, at least one external connection terminal 15 has a
It is preferable that one via hole connection portion 16 is formed inside the ceramic substrate 11 so as to be connected to at least one of the external connection terminals 15. Such a via-hole connection portion 16 is provided on the ceramic substrate 1 of the external connection terminal 15.
1 has a function of improving the bonding strength to the external connection terminal 15, even if it is electrically connected to an internal circuit (not shown) to perform the function of electrical connection. And may be formed only for the purpose of improving the bonding strength.

The ceramic substrate 11 has its main surface 1
As long as the external connection terminal 15 is provided on the substrate 4, the external connection terminal 15 may have a multilayer structure or a single layer structure. Further, the ceramic substrate 11
The ceramic may include a normal ceramic such as, for example, alumina, or may include a low-temperature sintered ceramic.

Such a surface mount type ceramic substrate 11
In FIG. 5, all the external connection terminals 15 are provided in a square terminal arrangement area 17 that leaves margins m1 and m2 of a width of 1 mm or more on the periphery of the main surface 14. The outline of the terminal arrangement region 17 is indicated by a broken line in FIG. Thus, as long as all the external connection terminals 15 are provided in the terminal arrangement region 17, the shape, size, and number of the external connection terminals 15 can be arbitrarily changed.

In this embodiment, as described above, the main surface 14 is square, and the length L1 of the vertical side 12 and the length L2 of the horizontal side 13 of the main surface 14 are both 10 mm or more. The first case in which the length L1 of the vertical side 12 and the length L2 of the horizontal side 13 are 14 mm or more;
There is a second case where the length L1 and the length L2 of the horizontal side 13 are less than 14 mm. In the first case and the second case, the setting of the dimensions of the terminal arrangement region 17 is different. .

That is, in the first case where the length L1 of the vertical side 12 and the length L2 of the horizontal side 13 are 14 mm or more,
Length a1 and horizontal side 19 of vertical side 18 of terminal arrangement area 17
Are set to have a length of 12 mm or less.

On the other hand, in the second case where the length L 1 of the vertical side 12 and the length L 2 of the horizontal side 13 of the main surface 14 are less than 14 mm, the length of the vertical side 18 of the terminal There is no restriction on each of the length a2 and the length a2 of the lateral side 19, and as described above, the terminal arrangement region 17 simply has a margin m1 and m2 with a width of 1 mm or more at the periphery of the main surface 14. It should just be done.

The preferred dimensional range of the terminal arrangement region 17 and the preferred dimensional ranges of the margins m1 and m2 are obtained as follows.

FIG. 2 shows a surface mount type ceramic substrate 21.
The external connection terminal 23 provided on the main surface 22 is shown.

By being connected to a conductive land on the motherboard (not shown) via the external connection terminal 23,
In the ceramic substrate 21 surface-mounted on the motherboard, when the ceramic substrate 21 is broken by the stress exerted by the motherboard, the breaking proceeds in a direction in which the strength of the ceramic substrate 21 becomes lower. Therefore, as shown by the broken line 24 in FIG. 2, the destruction of the ceramic substrate 21 occurs between the external connection terminal 23 and the edge of the ceramic substrate 21, that is, the margin m.
It is easy to occur in the part. Further, the smaller the width of the margin m is, the more easily such destruction occurs.

In order to prevent the above destruction, it is preferable that the width of the margin m is 1 mm or more, as described above. To confirm this, the length L of each side of the main surface
The width of the margin m was variously changed while using a multilayer surface-mount type ceramic substrate having a square of 1, L2 of 10 mm, and a bending test was performed for each width of the margin m. The results are shown in Table 1 below.

[0030]

[Table 1] In Table 1, “bending” indicates the maximum value of the bending of the motherboard in which the ceramic substrate did not break down in a state where the ceramic substrate was surface-mounted on the motherboard. 1mm
In each case, the bending of the motherboard immediately before the ceramic substrate is broken is shown. For example, in Table 1,
If the “bending” is 2.2 mm, the bending is 2.2 mm
No fracture occurred, but 2.3 mm indicates that fracture occurred.

Sample 1 in Table 1 has an external connection terminal having a structure like the external connection terminal 2 shown in FIG.

From Table 1, it can be seen that the greater the margin m, the greater the deflection of the motherboard that the ceramic substrate can withstand from breaking. Then, when the margin m becomes 1 mm as in the sample 4, the deformation of the motherboard that the ceramic substrate can withstand from destruction,
It can be as large as 2.2 mm. As can be seen from the above, by setting the margin m to 1 mm or more, it is possible to prevent the ceramic substrate from being broken even by a large deflection of 2.2 mm or more.

From the results of the bending test shown in Table 1 above, the margin m is set to 1 in order to prevent the ceramic substrate from being broken.
It can be seen that the minimum value of the margin m in this preferable range is 1 mm. Therefore, as the size of the ceramic substrate increases, the maximum allowable spread of the terminal arrangement region also increases. growing.
However, as described below, there is a preferable range in the expansion of the terminal arrangement region in order to prevent the ceramic substrate from being broken.

FIG. 3 shows a surface mount type ceramic substrate 31.
Are shown by dashed lines while the surface is mounted on the motherboard 32, and the state where the motherboard 32 is bent is shown by a solid line.

Referring to FIG. 3, when the motherboard 32 bends as shown by the solid line, the amount of displacement caused by the bending varies from place to place, and the amount of displacement d1 at a place farther from the center of the motherboard 32 becomes larger. It becomes larger than the displacement amount d2 at a close place. Therefore, motherboard 32
The stress applied to the surface-mount type ceramic substrate 31 due to the bending of
It occurs more greatly where the displacement d1 occurs.
To put it simply, on the main surface 33 of the ceramic substrate 31 on the side where the external connection terminals (not shown) are located, a greater stress is generated at the peripheral portion than at the central portion.

From this, it is sufficient that the terminal arrangement area where the external connection terminals are provided does not spread so much from the center portion on the main surface 33 of the ceramic substrate 31 to the peripheral edge portion, whereby the motherboard 32 bends. It can be seen that the stress exerted on the ceramic substrate 31 can be made lower than the stress that causes the ceramic substrate 31 to be broken.

Based on such knowledge, the extension of the terminal arrangement region 17 on the main surface 14 of the surface mount type ceramic substrate 11 shown in FIG. 1, that is, the length a1 of the vertical side 18 and the length a2 of the horizontal side 19 In order to find a preferred range in,
As the surface-mount type ceramic substrate, a multilayer structure having a square main surface having both a vertical length L1 and a horizontal length L2 of 20 mm is used. While arranging the square terminal arrangement area, the length a1 of the vertical side and the length a of the horizontal side of the terminal arrangement area
2 was changed variously, and a bending test was performed in each case. The results are shown in Table 2 below.

[0038]

[Table 2] In Table 2, the length “a1, a2” of the side of the terminal arrangement area
In addition, margins “m1, m2” are also described.
Further, “bending” is obtained by the same method as in Table 1.

Sample 15 in Table 2 is provided with an external connection terminal having a structure like the external connection terminal 2 shown in FIG.

From Table 2, it can be seen that the side lengths a1,
In samples 11 to 13 in which a2 is 12 mm or less,
It can be seen that the ceramic substrate is not broken even by a large deflection of 1.8 mm or more. On the other hand, as in samples 14 and 15, the length a of the side of the terminal
When 1, a2 exceeds 12 mm, the ceramic substrate can withstand only a small deflection of 1.3 mm or 1.0 mm from breaking.

Paying particular attention to the sample 14, this sample 14
Then, the margins m1 and m2 are 3mm and 1mm
Despite the above, the deflection of the motherboard that the ceramic substrate can withstand from breaking is as small as 1.3 mm. From this, even if the margins m1 and m2 are 1 mm or more, the lengths a1 and a2 of the sides of the terminal arrangement region are 12 m.
It can be seen that when m exceeds 1, the ceramic substrate can only withstand a small deflection of 1.3 mm from breaking.

From the results of the bending test shown in Table 2 above, it can be seen that the lengths a1 and a2 of the sides of the terminal arrangement region are preferably 12 mm or less. Since the preferred range of m2 is 1 mm or more, when the lengths L1 and L2 of the main surface are less than 14 mm, the side length a of the terminal arrangement region is inevitably
1, a2 becomes 12 mm or less. For this reason, the condition that the side lengths a1 and a2 of the terminal arrangement region are 12 mm or less is applied because the side lengths L1 and L2 of the main surface are different.
Is 14 mm or more.

To be more precise, the length L1 of the vertical side of the main surface
When at least one of the lengths L2 of the horizontal sides is 14 mm or more, the terminal arrangement extends in parallel with the side having at least one of the vertical sides and the lengths of 14 mm or more. The side of the region is set to have a length of 12 mm or less. On the other hand, when both the length L1 of the vertical side and the length L2 of the horizontal side of the main surface are less than 14 mm, each of the length a1 of the vertical side and the length a2 of the horizontal side of the terminal arrangement region is determined. There is no restriction, and the terminal arrangement region is simply provided with a margin m having a width of 1 mm or more at the peripheral portion of the main surface.
1 and m2 are set.

FIGS. 4 and 5 show a surface mount type ceramic substrate 11a according to the second and third embodiments of the present invention.
FIG. 2 is a view corresponding to FIG. 1 and showing FIGS. 4 and 5, elements corresponding to the elements shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted.

The ceramic substrates 11a and 11b shown in FIGS. 4 and 5, respectively, are different from the ceramic substrate 11 shown in FIG. 1 in that they have a long main surface 14. The features of the present invention will be described below with respect to the ceramic substrates 11a and 11b having such shapes.

Surface Mount Type Ceramic Substrates 11a and 11
1b both have a main surface 14 in which the length L2 of the horizontal side 13 is longer than the length L1 of the vertical side 12.

With respect to such lengths L1 and L2,
(1) L2 is not less than 14 mm, (2) L2 is not less than 10 mm and less than 14 mm, and
In the former case (1), there are a case where (1-a) L1 is also 14 mm or more and a case where (1-b) L1 is less than 14 mm.

In the case of the above (1), first, the margins m1 and m2 of the terminal arrangement area 17 where the external connection terminals 15 are provided are set so as to have a width of 1 mm or more. In the case of (1-a), the lengths L1 and L1
2 is 14 mm or more, so that the terminal arrangement area 17
Both the length a1 of the vertical side 18 and the length a2 of the horizontal side 19 are 12 mm or less. On the other hand, in the case of (1-b), since only the length L2 is 14 mm or more, the side of the terminal arrangement region 17 extending parallel to the side 13 of the main surface 14 having the length L2. Only the length a2 of 19 is 12
mm or less. The vertical side 18 of the terminal arrangement area 17
Is the length L1 of the vertical side 12 of the main surface 14.
Is less than 14 mm and the margin m1 is 1 mm or more, so that it is necessarily 12 mm or less.

In the case of (2), it is only necessary to satisfy the condition that both the margins m1 and m2 of the terminal arrangement region 17 have a width of 1 mm or more.

The external connection terminals 15 shown in FIGS. 4 and 5 are different from those shown in FIG. 1 in shape, size and number, but this is not an essential difference.

[0051]

As described above, according to the present invention, at least one of the vertical side and the horizontal side of the main surface has a length of 10 mm or more, and a plurality of external connection terminals having an area array structure are provided on the main surface. In the case where at least one of the vertical side and the horizontal side of the main surface has a length of 14 mm or more in the surface mount type ceramic substrate provided with And at least one of a vertical side and a horizontal side of the main surface, which is provided in a rectangular terminal arrangement area leaving a margin of 1 mm or more in width.
The side of the terminal arrangement region extending in parallel to the side having a length of 4 mm or more is made to have a length of 12 mm or less, and both the vertical side and the horizontal side of the main surface have a length of less than 14 mm. In this case, since all the external connection terminals are provided in the square terminal arrangement area leaving a margin of 1 mm or more in the peripheral portion of the main surface, the conductive terminals on the motherboard are connected via the external connection terminals. By being connected to the land, in the state of being surface-mounted on the motherboard,
The stress exerted on the surface-mount type ceramic substrate due to the bending, thermal shock, dropping, vibration, etc. of the motherboard can be kept low, and therefore, it is possible to advantageously prevent the ceramic substrate from being broken or the external connection terminals from being peeled off. And the reliability of the electrical connection with the motherboard can be improved. Similarly, it can also contribute to prevention of mechanical damage and connection failure on the motherboard side.

When at least one via hole connection portion connected to at least one of the external connection terminals is formed inside the surface mount type ceramic substrate according to the present invention, the strength of the external connection terminal is higher. The reliability of the electrical connection with the motherboard can be further improved.

Further, the present invention can be advantageously applied to a surface mount type ceramic substrate including a low-temperature sintered ceramic. That is, the mechanical strength such as hardness and flexural strength of low-temperature sintered ceramics is generally only about 60% of that of ceramics such as alumina. According to the present invention, even in the case of a surface-mount type ceramic substrate including a low-temperature sintered ceramic having such a low strength, the stress exerted by bending of the motherboard can be reduced as described above. Can be realized.

[Brief description of the drawings]

FIG. 1 is a plan view showing a surface mount type ceramic substrate 11 according to a first embodiment of the present invention.

FIG. 2 is an enlarged plan view showing a part of a main surface 22 of a surface mount type ceramic substrate 21 and shows a state in which destruction is about to occur.

FIG. 3 is a front view schematically showing a state in which the surface mount type ceramic substrate 31 is mounted on a motherboard 32 and a state in which the motherboard 32 is bent.

FIG. 4 is a plan view showing a surface mount type ceramic substrate 11a according to a second embodiment of the present invention.

FIG. 5 is a plan view showing a surface mount type ceramic substrate 11b according to a third embodiment of the present invention.

FIGS. 6A and 6B show a conventional surface mount type ceramic substrate 1 of interest to the present invention, wherein FIG. 6A is a plan view and FIG. 6B is a side view.

FIG. 7 is a plan view showing another conventional surface mount type ceramic substrate 6 which is of interest to the present invention.

[Explanation of symbols]

 11, 11a, 11b Surface mount type ceramic substrate 12 Vertical side of main surface 13 Horizontal side of main surface 14 Main surface 15 External connection terminal 16 Via hole connection part 17 Terminal arrangement area 18 Vertical arrangement side of terminal arrangement area 19 Horizontal arrangement of terminal arrangement area Side m1, m2 Margin L1 Length of vertical side of main surface L2 Length of horizontal side of main surface a1 Length of vertical side of terminal arrangement area a2 Length of horizontal side of terminal arrangement area

 ──────────────────────────────────────────────────続 き Continued on front page (72) Inventor Norio Sakai 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Inside Murata Manufacturing Co., Ltd. (72) Isao Kato 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Stock Company Inside Murata Manufacturing (72) Inventor Atsushi Kumano 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Prefecture Murata Manufacturing Co., Ltd.

Claims (6)

[Claims] 1. A rectangular main surface defined by a vertical side and a horizontal side, at least one of the vertical side and the horizontal side has a length of 10 mm or more, and an area array structure on the main surface. A plurality of external connection terminals are provided, and are connected to conductive lands on the motherboard via the external connection terminals, so as to be surface-mounted on the motherboard. At least one of the vertical side and the horizontal side of the surface has a length of 14 mm or more, and all the external connection terminals have a width of 1 mm on the periphery of the main surface.
The main surface is provided in a rectangular terminal arrangement area leaving a margin of at least mm, and extends in parallel to a side having a length of at least 14 mm, which is at least one of the vertical side and the horizontal side of the main surface. A surface mounting type ceramic substrate, wherein a side of the terminal arrangement region has a length of 12 mm or less. 2. A rectangular main surface defined by a vertical side and a horizontal side, at least one of the vertical side and the horizontal side has a length of 10 mm or more, and an area array structure on the main surface. A plurality of external connection terminals are provided, and are connected to conductive lands on the motherboard via the external connection terminals, so as to be surface-mounted on the motherboard. Both the vertical side and the horizontal side of the surface are 14 mm
And all the external connection terminals have a width of 1 at the periphery of the main surface.
A surface-mounted ceramic substrate provided in a square terminal arrangement region that leaves a margin of at least mm. 3. The surface mount type ceramic substrate according to claim 1, wherein at least one via hole connection portion connected to at least one of said external connection terminals is formed inside. 4. The surface mount type ceramic substrate according to claim 1, comprising a low-temperature sintered ceramic. 5. The surface mount type ceramic substrate according to claim 1, which has a multilayer structure. 6. The surface-mounted ceramic substrate according to claim 1, which has a single-layer structure.