JP2000332168A - Mounting structure of lsi package - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mounting structure of an LSI package in which the bypass capacitor in the LSI package can be disposed closely to the package. SOLUTION: An LSI package 100, a first interposer board 101, a first printed wiring board 102 with a conduction material, a second interposer board 1, and a second wiring board 2 are stacked at a predetermined position and connected conductively by applying pressure by means of a screw 106 with a spring. According to the structure, a bypass capacitor 3 can be disposed closely to the LSI package 100.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounting structure of an LSI package, and more particularly to a mounting structure of an LSI package in which a bypass capacitor conductively connected to an LGA type LSI package has an enhanced noise suppressing effect.

[0002]

2. Description of the Related Art In recent years, as mobile terminals such as mobile phones and video movies have become smaller, there has been a strong demand for smaller and thinner LSI packages used therein. One example of an LSI package that meets this requirement is a CSP (chip size package).
and Grid Array) type LSI package (planar terminal type LS
I package).

The feature of the LGA type LSI package is BGA
(Ball Grid Array) does not have solder balls on the bottom surface, but instead has many connection terminals (lands) on the back surface
Are arranged in a matrix and are mechanically pressed to a printed wiring board via an interposer substrate, as described below, to obtain electrical connection.

FIGS. 4A and 4B show a conventional LGA type L.
FIG. 3 is a side view when the SI package is mounted on a printed wiring board via an interposer substrate, and a side sectional view of the interposer substrate. 4A and 4B, 100 is an LGA type LSI package, 101 is an interposer substrate described below, 102 is a printed wiring board to be mounted, 103 is a metal plate (holding plate) coated with an insulating film, 104 is a heat spreader (heat conductive plate), 105
Is a heat sink, and 106 is a screw with a spring for fixing and crimping each of the members 100 to 105.

[0005] The interposer substrate 101 is shown in FIG.
As shown in (B), the connection lands 10 penetrate through the upper and lower surfaces of the interposer substrate body 101a made of ceramic or the like so as to correspond to the connection lands of the package 100.
The conductive members 101b with 1c are arranged in a matrix.
Then, with the interposer substrate 101 disposed between the LGA type LSI package 100 and the printed wiring board 102, mechanical pressure is applied from above and below by a screw 106 with a spring, and the land of the LGA type LSI package and the land of the interposer substrate are printed. The land of the wiring board is electrically connected.

[0006] By the way, current switching is required to operate the LSI package, and this switching causes a current fluctuation to generate noise. In order to suppress this noise, use a LGA type L bypass capacitor.
It is necessary to arrange as close as possible to the SI package 100 (for example, directly below the land side of the package 100).

[0007]

However, in the prior art, since the metal plate 103 insulated on the back side is directly in contact with the printed wiring board 102 as described above, the bypass capacitor cannot be arranged directly below the package 100. Was. Further, when a bypass capacitor is arranged around the package 100 as a next best measure in the case where it is impossible to dispose the capacitor directly below, not only the wiring property (the degree of freedom of wiring) is affected, but also the voltage is reduced. If there is a different IO buffer, it is necessary to devise power supply means such as increasing the number of power supply layers of the printed wiring board or dividing the inner layer, and this has made mounting design difficult. Furthermore, L
To increase the effect of the bypass capacitor by increasing the signal operating frequency of the SI package, it is necessary to reduce the inductance, and it is necessary to arrange the bypass capacitor as close as possible to the signal terminal of the LSI package.

An object of the present invention is to provide an LSI package mounting structure in which a bypass capacitor in an LSI package can be arranged as close to the package as possible.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a method of mounting an LSI package having a connection land on a bottom surface through a first interposer substrate having a conductive material penetrating through upper and lower surfaces. In an LSI package mounting structure in which the first printed wiring board is pressure-bonded to a connection land of the first printed wiring board to electrically connect the LSI package, the first interposer substrate, and the first printed wiring board, the first printed wiring board penetrates through upper and lower surfaces. And a second interposer substrate having a conductive material penetrating the upper and lower surfaces is disposed on the back side of the first printed wiring board with the conductive material.
A second printed wiring board for component mounting having a conductive material penetrating the upper and lower surfaces is disposed on the back surface side of the interposer substrate.

By doing so, for example, FIG.
As shown in (B), the LSI package (LGA type LS
I package) 100 and first interposer substrate 101
Printed wiring board (printed wiring board) 1 with conductive material
02, the second interposer substrate 1 and the second printed wiring board (small printed wiring board) 2 are overlapped at a predetermined position,
Since connection is made by applying pressure, bypass capacitor 3
Can be mounted and arranged near (immediately below) the LSI package 100.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiment. Note that the same reference numerals are given to the already described portions, and redundant description is omitted. The difference between the present embodiment and the conventional example is that the metal plate 103 (see FIG. 4A) of the conventional example is removed, and the second interposer substrate 1 and the small printed wiring board 2 are disposed instead, and the printed wiring The point is that the bypass capacitor 3 is arranged on the back surface of the plate 2.

FIGS. 1A and 1B are a side view of the present embodiment and a side sectional view of a second interposer substrate, and FIG. 2 is a view for explaining the crimping of each member. FIG. 3B is a diagram showing the relationship between the lands of the respective members and the crimping of the conductive material.

As shown in FIGS. 1A and 1B, the "first
On the back (lower surface) side of the printed wiring board 102 which is a "printed wiring board", the small printed wiring board 2 which is a "second printed wiring board" having a bypass capacitor 3 which is a "component" is mounted on the second interposer substrate 1. To place through. The second interposer substrate 1 has a matrix of conductive materials 1b that pass through the upper and lower surfaces of an interposer substrate main body 1a made of ceramic or the like and correspond to the lands of the printed wiring board 102. Reference numerals 1c denote lands provided in a matrix on both upper and lower surfaces of each conductive material 1b. That is, the second interposer substrate 1 secures electrical continuity by the land and the conductive material, and secures insulation by ceramics in portions other than the land. Also, the second interposer substrate 1
And the thickness of the small printed wiring board 2 is, for example, 1.6 mm.
By doing so, it is possible to withstand the pressure strength described below.

Then, as shown in FIGS. 2A and 2B, the heat sink 105 and the small printed wiring board 2 are fixed by a screw with a spring 106 which is a "pressing means".
In this manner, the land 100b of the LSI package 100, the upper land 101a of the interposer substrate 101, and the lower land 1 of the interposer substrate 101 are arranged in this order from the top.
01b and the upper land 102a of the printed wiring board 102
A lower land 102b of the printed wiring board 102;
An upper land 1a of the interposer substrate 1, a lower land 1b of the second interposer substrate 1, and a small printed wiring board 2
By pressing the lower lands 2a respectively, electrical connection between the lands is secured. 101c, 102c, 1
c and 2c are conductive members (for example, through holes) of each member.

Next, the operation will be described. When a current fluctuation occurs due to switching in the LGA type LSI package 100, the electric charge stored in the bypass capacitor 3 is transferred to the small printed wiring board 2, the interposer substrate 101, the second interposer substrate 1, and the printed wiring board 102.
Supplied to the GA type LSI package 100 to suppress noise. In this case, as shown in FIG. 2B, the shortest distance is secured between the bypass capacitor 3 and the LGA type LSI package 100.

Further, as shown in FIGS. 3A and 3B, LS
Even if the I package 10 includes IO buffers having different voltages, it is possible to mount a bypass capacitor for noise suppression separately for each voltage group. That is, for example, LVC
MOS (2.5V) has bypass capacitor 3a, GTL + (1.
5V) and a bypass capacitor 3c for HSTL (1.5V). In this way, it is not necessary to provide a plurality of power supply layers of the printed wiring board in the peripheral area of the LSI package or to divide the power supply layers into inner layers.

In this embodiment, the case of an LGA type LSI package has been described. However, the present invention can be applied to any type of LSI package that performs electrical connection to a printed wiring board for mounting by crimping. Of course.

[0018]

As described above, according to the present invention, the following effects can be obtained. The bypass capacitor can be arranged directly below the LSI package, and low inductance can be realized as compared with the case where the bypass capacitor is arranged outside the printed wiring board. The bypass capacitor can be mounted effectively without affecting the signal wiring on the printed wiring board.

[Brief description of the drawings]

FIG. 1A is a side view of an embodiment of the present invention, and FIG. 1B is a side view of a second interposer substrate constituting the embodiment.

FIGS. 2A and 2B are views for explaining the crimping of each member in the embodiment, wherein FIG. 2A is a conceptual diagram of the crimping, and FIG.

FIG. 3 is a diagram illustrating a case where an LSI package includes IO buffers having different voltages.

4A and 4B are diagrams illustrating a conventional example, in which FIG. 4A is a side view, and FIG. 4B is a diagram illustrating the operation of an interposer substrate constituting the conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 interposer substrate 1a interposer substrate main body 1b conductive material 1c connection land 2 small printed wiring board 2a connection land 2c conductive material 3 bypass capacitor 100 LGA type LSI package 100b connection land 101 interposer substrate 101a, 101b connection land 101c conductive material 102 printed wiring board 102a, 102b connection land 102c conductive material 104 heat spreader 105 heat sink 106 screw with spring

Claims (6)

[Claims] 1. An LSI package having a connection land on a bottom surface is crimped to a connection land of a first printed wiring board to be mounted via a first interposer substrate having a conductive material penetrating the upper and lower surfaces thereof. In a mounting structure of an LSI package for electrically connecting a package, a first interposer substrate, and a first printed wiring board, a conductive material penetrating upper and lower surfaces is provided on the first printed wiring board, and the first printed wiring board with the conductive material is provided. A second interposer substrate having a conductive material penetrating the upper and lower surfaces is disposed on the back surface side of the substrate, and a second printed wiring board for component mounting having a conductive material penetrating the upper and lower surfaces on the back surface side of the second interposer substrate A packaging structure of an LSI package, wherein: 2. The method according to claim 1, wherein the LSI package, the first interposer substrate, the first printed wiring board with a conductive material, the second interposer substrate, and the second printed wiring board are overlapped at a predetermined position, and are electrically connected by applying pressure. 2. The mounting structure of an LSI package according to claim 1, wherein: 3. The mounting structure of an LSI package according to claim 1, wherein the component mounted on the second printed wiring board is a capacitor. 4. The method according to claim 2, wherein a heat sink is disposed on the front side of the LSI package, and a pressure between the heat sink and the second printed wiring board is pressed by a pressing unit. Mounting structure of LSI package. 5. The mounting structure for an LSI package according to claim 4, wherein said pressing means is a screw with a spring. 6. The LSI package is an LGA type LS
The mounting structure of an LSI package according to claim 1, wherein the mounting structure is an I package.