JPH06252326A - Multi-terminal component, wiring substrate and packaging structure of multi-terminal component - Google Patents

Abstract

PURPOSE:To increase the surface tention of a fused solder in the case lead terminals are self-aligned without increasing the packaging area in relation to the packaging technology of multi-terminal components such as LSI, etc., on a wiring substrate by reflow soldering step. CONSTITUTION:Within the title packaging structure, alignment terminals 5 in larger area than that of lead terminals 2 are provided on a package 1 while alignment lands 6 are provided on the positions corresponding to the soldering surfaces of the alignment terminals 5 on the wiring substrate side as well as the lead terminals 2 and the alignment terminals 5 of the multi-terminal component are respectively reflow-soldered onto the terminal lands 4 and the alignment lands 6 on the substrate 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for mounting a multi-terminal component such as an LSI on a wiring board by reflow soldering.

[0002]

2. Description of the Related Art FIGS. 5A and 5B are plan views of a conventional multi-terminal component and a wiring board. (A) As shown in the figure,
A large number of lead terminals 2 are projected from each side of the package 1 of the multi-terminal component. On the other hand, as shown in FIG.
On the wiring board 3 side, a large number of lands 4 for soldering are arranged corresponding to the lead terminals 2 of the multi-terminal component. Preliminary solder is previously attached to the lead terminals 2 and the lands 4 of the package 1.

At the time of mounting, as shown in (c) (front view), the package 1 is placed on the wiring board 3, and the lead terminals 2 of the package 1 are positioned on the lands 4 of the wiring board 3. In the combined state, the lead terminals 2 ... Are heated all at once in the furnace or by a heater and the lands 4 ...
When pressed upward, the preliminary solder attached to the lead terminals 2 and the lands 4 is melted and soldering is performed. That is, reflow soldering is performed in a state in which the lead terminals 2 of the package are accurately positioned on the lands 4 of the wiring board.

[0004]

By the way, as the density of multi-terminal components is increased, the terminal pitch of the lead terminals is, for example,
Since it is becoming narrower than 0.8mm, it is necessary to accurately align each lead terminal of the package with the corresponding land on the wiring board. Therefore, conventionally, a method of transferring a package to a wiring board by using a jig and transferring the solder to a soldering step has been performed, but there is a problem that the man-hours are large and workability is poor. is there.

In the method of mounting with an automatic machine, it is possible to improve the accuracy of the mounting machine, but there is a limit. On the other hand, there is known a method of performing self-alignment by utilizing the surface tension of the molten solder at the time of reflow soldering after aligning with an automatic machine. For example, when the package 1 is displaced in the rotation direction as shown by the chain line in FIG. 6A, the lead terminal 2 is slanted with respect to the land 4 as shown in FIG. 6B. When the package 1 is displaced in the X and Y directions, the lead terminal 2 is in parallel with the land 4 as shown in FIG.

Even if such a slight displacement occurs, when the package is freed after the package is aligned by an automatic machine during reflow soldering, the lead terminals 2 ... Are caused by the surface tension of the molten solder. Are attracted to land 4. Then, as shown in FIG.
..., if it is exactly over the corresponding land 4, the surface tension will be the smallest and the package 1 will be stable.
The solder hardens in that state. This method also has the advantage that it can be soldered together with other surface mount components in the furnace.

However, the surface tension of the molten solder is not sufficient to move the package to the proper position. Therefore, by increasing the length of each lead terminal and increasing the soldering area, Attempts have been made to increase the surface tension. However, if the lead terminals are made long, the area required for mounting becomes large, which goes against the demand for high-density mounting.

The technical problem of the present invention is to pay attention to such a problem, and to increase the surface tension of the molten solder when the lead terminals are self-aligned without increasing the mounting area.

[0009]

FIG. 1 is a plan view for explaining the basic principle of a mounting structure for a multi-terminal component, a wiring board and a multi-terminal component according to the present invention. Claim 1 is an invention of a multi-terminal component, and as shown in FIG. 1A, a large number of lead terminals 2 are
In the multi-terminal component that is reflow-soldered to the land of the wiring board, in addition to the lead terminal 2, the positioning terminal 5 having a larger soldering area than the lead terminal 2 is provided. The alignment terminal 5 may be projected to the outside of the package 1 as shown in FIG. 1 or may be bent to the lower side of the package 1 as shown in FIG.

A second aspect of the present invention is an invention of a wiring board in which multi-terminal parts are reflow-soldered. As shown in FIG.
A wiring board for mounting a multi-terminal component having a large number of lead terminals by reflow soldering.
At a position corresponding to the soldering surface of the positioning terminal 5, the positioning land 6 having a size corresponding to the soldering surface of the positioning terminal 5 is provided.

A third aspect of the present invention is an invention of a structure in which a multi-terminal component is mounted on a wiring board by reflow soldering. The lead terminal 2 and the positioning terminal 5 of the multi-terminal component according to claim 1 are the inventions of claim 2 and 3. Are reflow-soldered to the terminal lands 4 and the alignment lands 6 of the wiring board 3.

According to a fourth aspect of the present invention, the alignment terminal 5 of the first or third aspect extends from the die pad of the lead frame.

[0013]

According to the present invention, the positioning terminal 5 having a larger soldering area than the lead terminal 2 is provided in the package 1, and the positioning terminal 5 is provided on the wiring board 3 side as in the second aspect. An alignment land 6 is provided at a position corresponding to the soldering surface of the. Then, as in claim 3, the lead terminal 2 and the positioning terminal 5 of the multi-terminal component according to claim 1 are connected to the terminal land 4 of the wiring board 3 according to claim 2.
When the mounting structure is formed by reflow soldering the positioning lands 6 and the positioning lands 6, respectively, when the multi-terminal component is reflow-soldered on the wiring board, between the positioning terminals 5 and the positioning lands 6 having a large soldering area, Since a large surface tension is generated by the molten solder, the self-alignment is performed more reliably.

Further, as in claim 4, the positioning terminal 5 of claim 1 or 3 is extended from the die pad of the lead frame, so that the number of steps for providing the positioning terminal 5 is increased. In addition, the heat generated from the element can be effectively dissipated.

[0015]

EXAMPLES Next, practical examples of how the multi-terminal component, the wiring board, and the mounting structure of the multi-terminal component according to the present invention are embodied will be described. FIG. 2 is a plan view illustrating a method for manufacturing a multi-terminal component according to the present invention. FIG. 3A shows a state of a lead frame. Like the normal lead frame, the lead frame 7 has a die pad 8 formed in the center and a lead portion formed in a radial shape for die bonding a semiconductor chip. The outer end 2 becomes a lead terminal.

Further, according to the present invention, the alignment terminals 5 having a large lead width extend from the die pad 8 toward the four corners, and each alignment terminal 5 has a wider soldering surface than the lead terminals 2. The alignment terminal 5 and the lead terminal 2 have outer ends integrally connected to the lead frame 7, but the chip is mounted on the die pad 8 and wire bonding is performed to the inner end of the lead portion of each lead terminal 2, After molding the parts other than the parts, while bending the lead terminal 2 and the positioning terminal 5,
When the outer ends of the terminal portions are cut at the position of the chain line 10 and separated from the lead frame 7 all at once, a multi-terminal component is completed as shown in FIG.

When this package 1 is reflow-soldered on a wiring board, it becomes as shown in FIG. Ie 4
Since the height H from the top end of the package to the soldering surface of the package is the same as that of the lead terminals 2, the alignment terminals 5 of the book are aligned when the lead terminals 2 come into contact with the terminal lands 4. 5 also contacts the alignment land 6.
As a result, the lead terminals 2 are soldered to the terminal lands 4 and the alignment terminals 5 are soldered to the alignment lands 6 all at once.

As shown in FIG. 3A, each alignment terminal 5 is formed together with the die pad 8, the lead terminal 2, etc. by pressing or etching. It doesn't increase. Further, since the die pad 8 and the positioning terminals 5 at the four corners are integrally connected by the connecting portion 9 having a wide lead width,
The heat generated by the elements on the die pad 8 is efficiently dissipated from the positioning terminals 5 and the positioning lands 6 having large areas.

As described above, when all the alignment terminals 5 are connected to the die pad 8, the terminals 5 and the alignment lands 6 are electrically dummy. On the other hand, if only one or two of the four connecting portions 9 are connected and the other portions are interrupted and the inner end is wire-bonded to the chip, the power supply terminal and the ground of the semiconductor chip are connected. It can be used as a terminal or a part of a signal terminal, and the number of terminals can be increased without increasing the size.

As shown in the drawing, the alignment terminals 5 at the four corners
When the outer ends of the lead terminals are aligned with the outer dimensions W1 and W2 of the vertical and horizontal lead terminals, the mounting terminal is not widened because the positioning terminals 5 having a large soldering area are provided.

3A and 3B show another embodiment of the alignment terminal 5. FIG. 3A is a bottom view of the package, and FIG. 3B is a side view of the mounted state. The alignment terminal 5 of FIG. 2 projects outward from the package 1 similarly to the lead terminal 2, while the alignment terminal 5 a of FIG. 3 is folded under the package 1.

The alignment terminal 5 is provided on the wiring board 3 side.
Positioning lands 6a are arranged on the lower side of the package 1 corresponding to the positions of a. Therefore, as shown in FIG. 7B, the surface tension of the molten solder during the reflow soldering is generated between the alignment land 6a and the alignment terminal 5a on the lower side of the package 1 and self-aligned. .

When the alignment terminals and the alignment lands are arranged on the lower side of the package 1 in this manner, the regions 11 outside the four corners of the package 1 are provided with alignment marks, mounting of other components, wiring, etc. Can be effectively used as an area. If the positioning terminals 5, 5a and the positioning lands 6, 6a are formed with holes having the same dimensions such as rectangles and circles, the surface tension of the molten solder in the self-alignment direction can be further increased.

In the above embodiment, the lead terminals are projected from the four sides of the package, whereas in the embodiment of FIG.
This is an IP type package, and the lead terminals 2 project from two sides. In this case, the alignment terminals 5b are provided outside the lead terminal rows on both sides, and the alignment lands are provided on the wiring board immediately below the alignment terminals 5b. In this case as well, the alignment terminal 5b can be folded under the package 1.

The lead terminal 2 and the positioning terminal 5 can be made stronger by making the outer end side thicker than the lead inner end side for wire-bonding a semiconductor chip. Although ICs and LSIs have been described above as examples, it goes without saying that the present invention can also be applied to other electronic components and multichip modules.

[0026]

As described above, according to the present invention, the package 1 is provided with the alignment terminal 5 having a larger soldering area than the lead terminal 2, and the solder of the alignment terminal 5 is provided on the wiring board side. Since the positioning land 6 is provided at a position corresponding to the mounting surface, and when the lead terminal 2 is reflow-soldered, the positioning terminal 5 is reflow-soldered to the positioning land 6 of the wiring board 3. A large surface tension is generated by the molten solder between the alignment terminal 5 and the alignment land 6.

As a result, self-alignment is performed more reliably, and the mounting area does not become large unlike the conventional mounting structure in which the lead terminals are lengthened. Claim 4
According to this, since the alignment terminal 5 extends from the die pad of the lead frame, the number of steps for providing the alignment terminal does not increase, and the heat radiation effect of heat generated from the element can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view illustrating a basic principle of a mounting structure of a multi-terminal component, a wiring board, and a multi-terminal component according to the present invention.

FIG. 2 is a diagram illustrating a method for manufacturing a multi-terminal component according to the present invention.

3A and 3B show another embodiment of the alignment terminal, wherein FIG. 3A is a bottom view of the package, and FIG. 3B is a side view of the mounted state.

FIG. 4 is a plan view showing an example implemented in a DIP type package.

FIG. 5 is a diagram showing a conventional mounting structure for a multi-terminal component, a wiring board, and a multi-terminal component.

FIG. 6 is a plan view illustrating a positional deviation of lead terminals and a self-alignment action.

[Explanation of symbols]

 1 Package of multi-terminal parts 2 Lead terminal 3 Wiring board 4 Land for connecting lead terminal 5,5a, 5b Alignment terminal 6,6a Alignment land 7 Lead frame 8 Die pad 9 Wide lead joint 11 Outside of four corners of package Free space

Claims (4)

[Claims] 1. A multi-terminal component in which a large number of lead terminals are reflow-soldered to a terminal land of a wiring board, in addition to the lead terminals (2), a positioning terminal having a larger soldering area than the lead terminals (2). A multi-terminal component characterized in that (5) is provided. 2. In a wiring board for mounting a multi-terminal component having a large number of lead terminals by reflow soldering, a solder for an alignment terminal (5) having a larger soldering area than the lead terminal (2) of the multi-terminal component. A wiring board having an alignment land (6) having a size corresponding to the soldering surface of the alignment terminal (5) at a position corresponding to the attachment surface. 3. In a mounting structure in which lead terminals of a multi-terminal component are reflow-soldered to a terminal land of a wiring board, in addition to the lead terminal (2), the lead terminal is included in the multi-terminal component.
(2) Provide the alignment terminal (5) with a larger soldering surface, and place the alignment land (6) with a large soldering area at the position corresponding to the alignment terminal (5) on the wiring board side. Install the lead terminals (2) and connect them to the corresponding terminal lands (4) on the wiring board.
In addition, a mounting structure for a multi-terminal component, wherein the alignment terminal (5) is reflow-soldered to the corresponding alignment land (6) of the wiring board, respectively. 4. The mounting structure for a multi-terminal component according to claim 1, wherein the alignment terminal (5) extends from the die pad (8) of the lead frame.