JPH04354173A - Surface mounting parts and mounted parts of printed wiring board - Google Patents

Abstract

PURPOSE:To improve the parts mounting accuracy when the parts are mounted on and stuck to a printed wiring board by solder reflow. CONSTITUTION:At the time of mounting parts on a printed wiring board by solder reflow, a parts mounting structure in which surface mounting parts 7 and 8, each of which has a notch 6 on at least one side of its part except a solder pad section 5, are fitted to at least two corners of an IC package, such as a QFP 2, SOP, etc., is formed.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to surface-mounted components for mounting flat ICs and the like, and components mounted on printed wiring boards made of these components.

0002

[Prior Art] Conventionally, when mounting electronic components such as flat ICs on printed wiring boards, for example,
As shown in Publication No. 57 and Japanese Utility Model Application Publication No. 2-136358, protrusions that fit into holes in the printed circuit board are provided on the back side of the flat IC body, and parts similar in shape to those to be attached to the printed wiring board are provided. Even if you create a storage hole on the board and insert parts into the storage hole manually,
Techniques are known that allow easy alignment and prevent incorrect mounting.

0003

[Problem to be solved by the invention] However, in recent years,
QFP (Quart Flat Package), SOP (
The lead pitch of IC packages (hereinafter, QFP will be explained as a representative of these IC packages) such as single outline package) is becoming narrower, and if you try to mount a QFP with a pitch of 0.6 mm or less. However, since this requires a chip mounter with pattern recognition and is an expensive device, there is a problem in that the mounting cost is high. Also, once the IC is removed for modification, etc.
Mounting the QFP again was an extremely difficult task.

The present invention aims to solve the above problems, and its purpose is to provide a means for mounting IC packages such as QFPs and SOPs with high precision using either a mechanical chip mounter or a human hand. There is a particular thing.

[0005]

[Means for Solving the Problems] In order to solve the above problems, the surface mount component of the present invention is provided with a notch on at least one side of the component excluding the solder pad portion. The cutout preferably has an internal angle of approximately 90 degrees. Further, as another surface mount component, both sides of the component excluding the solder pad portion are formed in a protrusion shape.

The IC package of the present invention has notches at four corners of the IC body.

[0007]Furthermore, in the printed wiring board component mounting product of the present invention, the surface mount components in the notches shown above are mounted on an IC.
It is characterized in that it is arranged at at least two corners of the package. Another component-mounted product is characterized in that a surface-mounted component having the protrusion-shaped sides shown above is disposed at the corner of the notch shown above in the IC package.

[0008]

[Operation] Surface mount components configured as described above have a self-alignment effect during the solder reflow process, so if these surface mount components are mounted in advance at the corner of an IC package such as a QFP or SOP, these IC of
The package is guided to a defined desired position.

[0009]

[Embodiment] A QFP will be explained below as an example of a package, but it goes without saying that the same applies to an SOP as well. Embodiments will be explained with reference to the drawings. FIG. 1 shows a QF using the surface mount component of the present invention.
FIG. 2 is an explanatory diagram showing an example of a component mounting structure arranged at P, in which solder pads are placed so that two diagonally opposing corners 3 and 4 of a QFP 2 having lead terminals 1 serve as guides. Notch 6 with a 90 degree cutting angle on the part other than part 5
a surface mount component 7 provided on a line facing the corners 3 and 4;
, 8 are installed.

[0010] Here, the surface mount component is a small component of several millimeters square, which is first installed by reflow, and then a QFP of about 10 millimeters square is mounted and bonded.
The error with respect to the predetermined pattern position on the printed wiring board immediately after mounting was ±100 to 200 μm, but after bonding by reflow, the error was within ±20 to 100 μm. This is because the surface mount components, which are several millimeters square, exhibit a self-alignment effect during solder reflow, making highly accurate positioning and joining possible.

FIG. 2 is a partial explanatory diagram showing an example of another component mounting structure. A small surface mount component 13 is bonded onto the solder pads 9 and 10 via solder terminals 11 and 12, and Q
The corner 3 of the FP2 is arranged as a guide. When solder reflow was performed using such a component mounting structure, both the surface mount component 13 and the QFP 2 could be mounted with high precision.

FIG. 3 is a partial explanatory diagram showing an example of another component mounting structure of the present invention. A surface mount component 19 having protrusions 17 and 18 on a solder pad 16 is attached to a soldering terminal 20.
It is first joined by reflow through the . When disposing the QFP 2 on this surface mount component 19, the sides of the protruding portions 17 and 18 are approximately the same as the lead terminals 14 and 15 so that the lead terminals 14 and 15 provided at the corners 3 serve as guides. They are formed parallel to each other.

[0013] When solder reflow was carried out using such a component mounting structure, accurate mounting was achieved as in the previous embodiment.

As shown in FIG. 4, when two soldering terminals 21 and 22 were provided to bond the surface-mounted component 19, the self-alignment effect was enhanced and the mounting accuracy was improved.

FIG. 5 is a partial explanatory diagram showing an example of another component mounting structure of the present invention. Q in which a square-shaped surface mount component 24 is bonded on a solder pad 23 by reflow via a soldering terminal 25, and a notch 26 is provided in the rear corner 3.
When the FP2 was sandwiched between the lead terminals 27 and 28 with the surface mount component 24 and solder reflowed,
As with the previous example, accurate implementation was achieved.

[0016]

[Effects of the Invention] As explained above, since the surface mount component of the present invention has a cutout on at least one side of the part excluding the solder pad portion, it is necessary to bond it in a predetermined position in advance. IC such as QFP and SOP
The package can be positioned accurately by solder reflow. If the notch has an internal angle of approximately 90 degrees, the corner of a quadrangular IC package such as a QFP can be accurately guided to a predetermined position, and the mounting positioning accuracy can be extremely high. In addition, since the surface mount component of the present invention has protruding sides on both sides of the portion excluding the solder pad portion, it is possible to solder reflow IC packages such as QFP and SOP by bonding them at predetermined positions in advance. When bonding is performed, the lead terminals at the corners of an IC package such as a QFP or SOP are guided by the protruding portions of the surface mount component, making it possible to position them with high precision. The IC package of the present invention includes four parts of the IC main body.
Since there are notches at each corner, the same effects as described above can be obtained even when mounted in combination with a square-shaped surface mount component. The component mounting structure of the printed wiring board of the present invention has a structure in which the above-mentioned surface mount components are arranged in at least two corners of an IC package such as a QFP or SOP, so that high-precision mounting is possible by solder reflow. It is.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an example of a component-mounted product in which a QFP and a surface-mounted component of the present invention are disposed.

FIG. 2 is a partial explanatory diagram showing an example of another component mounting structure of the present invention.

FIG. 3 is a partial explanatory diagram showing an example of another component mounting structure of the present invention.

FIG. 4 is a partial explanatory diagram showing another component mounting structure of the present invention.

FIG. 5 is a partial explanatory diagram showing another component mounting structure of the present invention.

[Explanation of symbols]

1 Lead terminal 2 QFP (Quart Flat Package) 3
Corner 4 Corner 5 Solder pad portion 6 Notch 7 Surface mount component 8 Surface mount component 9 Solder pad portion 10 Solder pad portion 11 Solder terminal 12 Solder terminal 13 Surface mount component 14 Lead terminal 15 Lead terminal 16 Solder pad portion 17 Protrusion Shape portion 18 Projection shape portion 19 Surface mount component 20 Solder terminal 21 Solder terminal 22 Solder terminal 23 Solder pad portion 24 Surface mount component 25 Solder terminal 26 Notch 27 Lead terminal 28 Lead terminal

Claims (6)

[Claims] 1. A surface mount component having a notch on at least one side of the portion excluding the solder pad portion. 2. The surface mount component according to claim 1, wherein the cutout has an internal angle of approximately 90 degrees. 3. A surface mount component in which both sides of the portion excluding the solder pad portion are formed in a protrusion shape. 4. An IC package characterized by having notches at four corners of an IC body. 5. A component mounted product of a printed wiring board, characterized in that the surface mount component according to claim 1 or 2 is disposed at at least two corners of an IC package. 6. A component mounted product of a printed wiring board, characterized in that the surface mount component according to claim 3 is disposed at at least two corners of the IC package according to claim 4.