JPH06216273A - Signal line structure of high speed multiple pin package - Google Patents

Abstract

PURPOSE:To realize a high speed package in response to introduction of multiple pins by ensuring isolation between the adjacent signal lines which has been considered as a problem. CONSTITUTION:In view of realizing a large isolation of signal lines in the same layer of a high speed multiple-pin package, a quasi-coaxial constitution is formed by providing GND conductors 2 including projected areas arranged keeping a fine interval between signal lines 1 so that it is not extended up to the center and also providing the signal lines l between the upper and lower GND conductors 2. In such a constitution, only a small amount of magnetic force lines leak in the lateral direction. Therefore, the magnetic force lines are almost completely transmitted to GND both in the upper and lower sections. Thereby, a large isolation can be obtained and crosstalk can be suppressed. This constitution is more simpler than the perfect coaxial constitution and electrical performance is almost equal to that obtained in the coaxial constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal signal line structure for increasing isolation to enable a high-speed multi-pin package.

[0002]

2. Description of the Related Art Conventionally, strip lines have been used as signal lines for high-speed multi-pin packages. In the case of multiple layers, although isolation between layers can be achieved, at high speed, the isolation between adjacent strip signal lines in the same layer cannot be separated between signal lines because the package size is limited. In some cases, the specification conditions were not satisfied.

[0003]

Recently, a multi-pin high speed LSI has been developed.
Is actively developed, and at that time, isolation between adjacent strip signal lines requires at least 20 dB or more. To pass high-speed signals, it is possible to connect both ends of the conductors that are placed with the signal lines to GND, but in such an extreme case, the number of signal lines is halved. There were practical problems with the structure. As a conventional technique, there is a technique of forming a pseudo coaxial structure by arranging GND through holes on both sides of a signal line, but at high speeds, it is necessary to shorten the interval between the through holes.

FIG. 4 shows a sectional view of a conventional two-layer structure signal line. Reference numeral 1 is a signal line, 2 is a GND, and 3 is a dielectric.

An example of crosstalk measurement is shown in FIG. t
_r is the rise time of the pulse. The value of crosstalk assigned to the package is almost 5%, which needs to be kept below. In this example, the line pitch inside the package (where it is bonded) is 0.275 mm,
This is when the outer pitch is 1 mm. Radially spread from the inside to the outside, with a distance of 1.25 cm
This is the case when they are adjacent to each other. When the crosstalk was 5%, the rise was 600 to 700 psec. This is problematic for high speed use.

An object of the present invention is to provide a signal line structure of a high-speed multi-pin package that can secure isolation between adjacent signal lines, which has been a problem in the past, and realize a high-speed package in accordance with the increase in the number of pins. To provide.

[0007]

According to the present invention, in order to increase the signal line isolation within the same layer of a high-speed multi-pin package, the signal lines are arranged with a minute interval so as not to penetrate to the center. Providing a GND conductor having a protrusion,
A signal line is installed between the upper and lower GND conductors to form a quasi-coaxial structure. In such a structure, since there are few magnetic field lines leaking in the lateral direction, most of the magnetic field propagates to the GND both above and below. Therefore, the isolation is large,
Crosstalk can also be suppressed. The structure is simpler than forming a perfect coaxial, and the electrical performance is almost the same as the coaxial. This is similar to the coaxial structure, but its main feature is that it is easier to construct in terms of structure and assembly than coaxial. In the past, adjacent isolation was not able to be large due to coupling. The difference is that a GND is provided to avoid this coupling.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram for explaining an embodiment of the present invention, in which 1 is a strip signal line having a two-layer structure, 2 is a GND conductor, and 3 is a dielectric. The GND conductor 2 is composed of a plurality of conductor layers sandwiching each layer of strip signal lines with a dielectric 3 interposed therebetween, and each conductor layer is a protruding portion arranged with a minute gap g between adjacent strip signal lines of each layer. have.
As a result, each strip signal line has a quasi-coaxial structure in the direction perpendicular to the plane of the drawing. Due to such a structure, coupling from one strip signal line to an adjacent strip signal line is extremely small. As its effect, the isolation can be made sufficiently large as compared with the conventional technique. As a manufacturing method, the dielectric material is separated in the perfect coaxial structure for reception, but in the present invention, the quasi-coaxial structure is formed by preventing the dielectric material from being separated by the mold. A quasi-coaxial structure can be formed by printing or plating the metal portion so that the metal reaches the position of the groove, and in the case of ceramic, stacking and firing the metal.

Although the embodiment of FIG. 1 uses a strip signal line having a two-layer structure, the present invention can be applied to a multilayer structure and a single-layer structure signal line. Of course.

As an example, in the case of a strip line as shown in FIG. 4 and the present invention, as shown in FIG. 3, width W = 50 μm and thickness t.
= 20 μm and the dielectric constant ε _r of the dielectric 3 = 10, the coupling degree due to the capacitance with respect to the adjacent signal line was obtained by two-dimensional analysis. When Z ₀ was set to about 50Ω, the strip line had about 6% coupling with the adjacent signal line at a distance d = 300 μm, but in the case of the embodiment of FIG. 1 of the present invention, the coupling is about 0. ．
02% (when the gap g between the upper and lower conductors is 50 μm) or 1.76% (the gap g between the upper and lower conductors is 200 μm, that is, the gap H between the GND conductor layers is H = 400 μm. Half the time). In both cases, H = 400 μm and the case is ceramic, but the effect of GND is effective.

[0011]

As described above, the structure of the present invention is
Since there is a GND conductor that penetrates vertically through the signal line, it has a quasi-coaxial structure, and since the magnetic coupling between adjacent signal lines is small, the isolation is large and high-speed signals can also pass. There are great advantages when applied to high-speed multi-pin packages.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a characteristic diagram for explaining isolation between signal lines targeted by the present invention.

FIG. 3 is a cross-sectional view for explaining isolation between signal lines, which is a target of the present invention.

FIG. 4 is a cross-sectional view showing a conventional signal line structure.

[Explanation of symbols]

 1 Signal line 2 GND conductor 3 Dielectric 4 Protruding part g Minute interval

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location 9355-4M H01L 23/12 P

Claims (1)

[Claims] 1. A signal line structure for a high-speed multi-pin package of an LSI, wherein a plurality of GND conductor layers sandwiching a plurality of layers or a single layer structure of a strip signal line are sandwiched by dielectrics, wherein the plurality of GND conductors are provided. The layer has projecting portions arranged with a minute interval between two adjacent signal lines of the strip signal line, and a quasi-coaxial structure is formed in the line direction of each strip signal line. High-speed multi-pin package signal line structure.