JPH05343579A - Semiconductor mounting board - Google Patents

Abstract

PURPOSE:To obtain a semiconductor mounting board which can be commonly used for a circuit having partly different function by providing grooves for passing a wiring pattern on a printed circuit board or grooves for interrupting the pattern, mounting a semiconductor device, and forming a structure in which the wiring passing in the groove are solder-connected in the groove. CONSTITUTION:In the case of applying to a memory module, grooves 3 (31-35) are provided on a surface of a board 1 in which an IC memory 2 is mounted and printed wirings are provided, and groove conductors 8 (81-85) of printed wirings or equivalent wiring materials are formed on walls and bottoms of the grooves 3. Wirings 4 (41-45) are connected to the conductors 8, and connected at one end to a board terminal, and at the other to the printed wirings. The conductors 8 are cut substantially at the center of the groove 3, the cut conductor 81 of the groove 31 is connected to operate the memory 2 in a specific operation mode, or to prevent the specific operation, thereby obtaining a memory product having different functions.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circuit board on which a semiconductor device or the like is mounted, and more particularly to a circuit board which can realize different circuit functions using the same board.

[0002]

2. Description of the Related Art An example of a conventional semiconductor mounting substrate is shown in FIG.
Will be described. The semiconductor mounting board shown in the figure shows an example of a memory module in which a plurality of IC memories 2 are mounted on a printed wiring board 1. This memory module is inserted into a board connector of a CPU board (not shown) and used as a main memory of the CPU. The IC memory 2 has various operation modes such as a nibble mode, a page mode and a static column mode, and any one of the operation modes is selected and used. Further, the IC memory 2 has various specifications such as memory access time and memory capacity. The IC memory must be used according to the operating speed of the CPU, and the operating system allocates the storage area according to the memory capacity, so that the CPU can check the parameters of the memory module. A device is made. Such a check function is called presence detect.

The presence detect function is, for example, I
When the C memory is mounted on the board, a shorting chip called a chip jumper is mounted on the circuit of the board by using a solder paste so that certain information can be obtained from the board terminals.

Regarding the memory module, JEDE
C (Joint Electron Dvice Engneering Council)
The pin designation of the board connection connector of the 0-pin and 72-pin memory modules is defined. For custom memory modules, add or remove your own control pins using pins not used by the memory module. For this reason, a special board is being developed each time a special memory module is ordered.

[0005]

However, when mounting the above chip jumper, a surface mounter (Surface M) that mounts the chip jumper at a predetermined position on the substrate is used.
ounter) takes time to position. Due to variations in the amount of solder paste used to attach the chip jumper, problems such as misalignment of the chip jumper and solder flow may occur after reflow soldering. Further, in a memory module in which the terminal arrangement of the board is standardized, developing a dedicated board each time according to special specifications requires a period of time for development and increases costs. When mounting a device on a board, apply solder paste to the footprint of the wiring pattern to
Placed by mounter and attached with reflow solder. However, it is difficult to control the amount of solder constantly due to improper thickness of the metal mask or dust adhering to the metal mask. There is a problem such as peeling of solder. Due to the non-uniformity of the amount of solder, variations may occur in the thickness direction of the product after mounting.

Therefore, a first object of the present invention is to provide a semiconductor mounting board which can be shared by circuits having partially different functions. It is a second object of the present invention to provide a printed wiring board that can prevent misalignment and solder flow when soldering a device mounted on the printed wiring board.

[0007]

To achieve the above object, a semiconductor mounting board of the present invention comprises a printed wiring board having a wiring pattern formed on the surface of an insulating layer, and a plurality of operation modes connected to the wiring pattern. And a groove formed on the surface of the insulating layer across a part of a wiring pattern connected to a terminal that receives a command designating at least one operation mode of the semiconductor device among the wiring patterns. A groove conductor for connecting the wiring pattern interrupted by the groove through a conductor gap formed in the groove, and the groove for activating at least one operation mode of the semiconductor device. A solder connection layer formed so as to connect the conductor gap therein.

In the printed wiring board of the present invention, an insulating layer having a groove having a width corresponding to the wiring width is formed on the surface, and a part of the wiring formed on the insulating layer passes through the groove. And a pattern.

[0009]

[Function] A groove through which a wiring pattern passes, on a printed wiring board,
Alternatively, a groove for blocking the wiring pattern is provided, and the semiconductor device is mounted. The wiring which passes through the groove is soldered in the groove to selectively activate the wiring. Further, the terminals of the semiconductor device are soldered to the printed wiring in the groove. As a result, it is possible to select the signal line to be connected in the printed wiring of the board, and for example, it is possible to select the operation mode of the semiconductor device mounted on the board. In addition, by soldering in the groove, it is possible to avoid problems such as displacement of the mounted device, solder flow, insufficient solder, and reduce the thickness of the mounted board.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment in which the present invention is applied to a memory module, and an IC memory 2 is mounted on a substrate 1. Although not shown, printed wiring is provided on the substrate 1. On the surface of the substrate 1, groove (or counterbore) 3 ₁ to 3 ₅ are provided. Groove 3 ₁ to 3 ₅ each wall and the groove conductor 8 _{1-8 5} by printed wiring or equivalent wiring material on the bottom surface are respectively formed. The wiring ₄₁ to ₅ is connected to the groove conductor 8 _{1-8 5.} Groove conductor 8 _{1-8 5} and the wiring ₄₁ to ₅ can be formed as a printed pattern integrally. In the example of FIG.
One end of the wiring of the groove portion reaches the board terminal, and the other end is connected to the printed wiring of the board. Both ends of the groove conductor can be connected to the board terminals, or both ends can be connected to the printed wiring.

In the case of this embodiment, the groove conductor 8 is cut at approximately the center of the groove. For example, when the cut groove conductor 8 ₁ of the groove 3 ₁ is connected, the memory 2 operates in a specific operation mode or a specific operation is blocked. For example, a memory product having different functions can be configured on the same substrate by applying the read / modify function of the DRAM to the non-use, the use of the output enable of the control pin, and the setting of the non-use. In the case of a memory module, most of them are common to I / O, but I / O can be separated as desired by cutting the wiring.

Further, a plurality of grooves, for example, the grooves 3 _{two or} three grooves conductors open gap _5, the short access memory mounted on the memory module time by aspect, it is possible to display the memory capacity etc. .. This indication appears as high and low voltage levels at the board terminals and is read by the CPU.

The wiring is connected in the groove by, for example, reflow soldering. First, an IC memory and other parts are provided with a solder paste, an adhesive, an insertion hole, etc. on a board in which the above-mentioned groove is formed in advance and a wiring pattern, a connection hole, a component insertion hole, etc. are formed by a normal board mounting process. Use and install. Using a metal mask in which the groove portion of the wiring to be connected is opened, solder paste is put into the groove of the substrate through the opening portion of the mask. The solder paste is heated from an external heat source to a suitable temperature by radiation, conduction, convection or the like to connect the component to the substrate and the printed wiring and to melt the solder in the groove to connect the wiring in the groove. Remove the metal mask and apply insulating paint if necessary.

With this configuration, the amount of solder is accurately regulated by the groove and the metal mask, and the outflow of solder to the outside of the groove and the absence of solder are avoided.

FIG. 2 is a sectional view showing an example in which the present invention is applied to a multilayer printed wiring board. In the figure, four layers of conductor patterns 4 ₁ to ₄ 4 are provided between the front and back surfaces of the insulating substrate composed of three insulating layers 10, 11 and 12 and between the insulating layers.
Is formed. For example, 4 ₁ and 4 ₄ are signal layers,
4 ₂ is a power layer and 4 ₃ is a ground layer. Solder resists 13 and 1 are provided on the front and back surfaces of the multilayer printed wiring board.
4 is applied to protect the substrate surface with an insulating film.

Grooves 3f and 3g are formed in the insulating substrates 10 and 12, respectively. On the side wall and the bottom of the groove 3f, a conductor pattern 4 ₁ made of, for example, a printed wiring is inserted to form a groove conductor 8, and the groove conductor 8 is blocked at the central portion of the groove. The groove 3g on the back surface of the substrate is similarly configured.
As many such grooves as necessary are provided at necessary places. As the insulating substrate, a resin substrate such as glass epoxy, a composite substrate using an insulating layer, a base metal, or the like can be used. In particular, when it is necessary to form a thin mounting substrate, a ceramic substrate is used. To use. The ceramic substrate has sufficient insulation characteristics even if it is thin, and has good heat resistance.

When wiring is connected in this groove, a solder mask is applied to the groove using a metal mask in which the groove conductor 8 in the groove 3f and the groove conductor 8 in the groove 3g are opened. , Reflow to melt the solder. The metal mask opens only the portion of the substrate to be soldered and covers the other portions that are not to be soldered. Various metal masks corresponding to the wiring to be selected can be prepared in advance to avoid wiring mistakes in the soldered wiring.

FIGS. 3A to 3F show various plan views of the shape of the groove 3 and the gap shape of the groove conductor 8. The type of groove can be selected according to the shape with solder.

FIG. 4 shows another embodiment of the present invention. The printed wiring board 1 is provided with the groove 3, and the device 5
Are arranged so as to straddle the conductor 6 that supplies power.
The surface-mounting type terminals (leads) 7 of the device 5 are arranged in the groove 3 and soldered to the groove conductor (not shown) in the groove 3. In this case, the pattern of the groove conductor in the groove 3 is not cut midway. In this case, for soldering the groove conductor and the terminal 7, solder paste is applied to the groove conductor, the device 5 is arranged, and reflow is performed to melt the solder. In this way, the terminal 7 of the device 5 is hooked on the side wall of the groove, and the displacement of the device 5 is prevented. The groove prevents solder flow. In addition, the device 5 is provided by the depth of the groove.
Since the structure is embedded in the substrate, the thickness of the mounting substrate becomes thin.

FIG. 5 is a sectional view showing an example in which the structure shown in FIG. 4 is applied to a multilayer printed wiring board. Figure 4
2. In FIG. 2, the parts corresponding to those in FIG. The conductor patterns 4 ₁ and 4 ₄ are not cut in the grooves 3h and 3i. This groove can be supplied to the power supply terminal of the device (not shown) the power from the conductive pattern 4 ₂ is provided a through hole 15. When the terminal of the device is an empty terminal, the conductor pattern of the groove is used only for fixing the terminal, so that the conductor pattern is provided in the groove or in the vicinity of the groove while being insulated from others. ..

FIGS. 6A to 6E show various plan views of the shape of the groove 3 in the structure of FIG. The groove conductor 8 is not cut in the groove 3. The shape of the groove 3 is the device 5
It is preferable to select it in accordance with the end shape of the terminal 7. For example, if a groove is selected according to the shape of soldering to be applied to the end portion of the lead frame, it is possible to easily prevent a short circuit between adjacent terminals due to defective soldering.

[0022]

As described above, according to the present invention, soldering is performed using the groove formed on the surface of the substrate and into which the wiring pattern is inserted, and the signal path of the circuit prepared in advance is selectively formed. It is possible to provide products with different specifications using the same substrate. In addition, since wiring or devices are soldered in the grooves, it is possible to avoid problems due to solder flow, solder bridges, etc. during board assembly work. Further, since the leads of the device fit in the groove, it is possible to reduce the thickness of the mounting board.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory view showing an application example of the present invention to a multilayer wiring board.

FIG. 3 is an explanatory view showing an example of a groove shape and a wiring pattern in the groove of the present invention.

FIG. 4 is an explanatory view showing another embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an application example to a multilayer wiring board.

FIG. 6 is an explanatory view showing an example of the groove shape of the present invention.

FIG. 7 is an explanatory diagram showing a conventional example.

[Explanation of symbols]

 1 substrate 2 IC memory 3 groove 4 wiring 5 device 7 terminal (lead)

Claims (5)

[Claims] 1. A printed wiring board having a wiring pattern formed on a surface of an insulating layer, a semiconductor device connected to the wiring pattern and having a plurality of operation modes, and at least one of the semiconductor devices of the wiring patterns. A groove formed on the surface of the insulating layer across a part of a wiring pattern connected to a terminal that receives a command specifying the operation mode of the wiring pattern, and the wiring pattern interrupted by the groove formed in the groove. A groove portion conductor connected via a conductor gap, and a solder connection layer formed to connect the conductor gap in the groove in order to activate at least one operation mode of the semiconductor device, A semiconductor mounting substrate comprising: 2. An insulating layer having a groove having a width corresponding to the wiring width formed on the surface, and a wiring pattern formed on the insulating layer and having a part of the wiring passing through the groove. And a printed wiring board. 3. The printed wiring board according to claim 2, wherein a wiring pattern passing through the groove is interrupted in the groove. 4. The printed wiring board according to claim 2, wherein the terminals of the device to be mounted on the printed wiring board are soldered to a wiring pattern passing through the bottom of the groove. 5. The board according to claim 1, wherein the printed wiring board is a multilayer wiring board.