JPH0983132A - Circuit board lead terminal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce disconnection between a lead terminal and a lead electrode of a circuit board in a soldering process. SOLUTION: A circuit board lead terminal is formed with a conductive plate- shaped member, and includes a connection piece 18 conductively connected with lead electrodes 13 formed in the vicinity of a lower side of a circuit board 11 with which a circuit is constituted, and a pin 20 led from the connection piece 18 and extending downward from the connection piece 15, and having its tip end conductively fixed to a land electrode on a bus circuit board (b). The pin 20 is led from an intermediate part of the connection piece 18. The lead terminal is generally bent such that the side surface of the connection part 15 being an end thereof has a concave shape, whereby a holding piece 19 is provided facing the connection piece 18.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead terminal for a circuit board, which is electrically conductively fixed to a lead electrode of a circuit board on which a circuit is formed by a wiring pattern and circuit components mounted on the board.

[0002]

2. Description of the Related Art Conventionally, a circuit board used in a widely known hybrid integrated circuit device is one in which a wiring pattern is formed on an insulating substrate made of ceramic, glass-epoxy resin or the like. A circuit component is mounted on the circuit board, and lead terminals are attached to the circuit board to form a hybrid integrated circuit device. Among them, in particular, the single in-line type (SIL type) hybrid integrated circuit device has lead terminals led out from one side of the circuit board.

Such a hybrid integrated circuit device is mounted on a mother circuit board which constitutes another circuit device. For example, the SIL hybrid integrated circuit device is mounted on the mother circuit board with its lead terminal side facing down. Conventionally, a so-called gull wing type lead terminal is known as a lead terminal attached to a circuit board constituting such a SIL type hybrid integrated circuit device. As shown in FIG. 7, the gull wing type lead terminal is formed by bending a strip plate conductor. That is, the side of the connecting portion 5 is bent into a concave shape on the side surface to form the connecting piece 8 and the sandwiching 9 which face each other, and the side portion of the circuit board 1 is sandwiched between them. Further connecting piece 8
The end portion is bent into a side crank shape to form the leg portion 10.

The lead electrodes of the circuit board 1 are alternately formed on both right and left sides of the lower side of the circuit board 1 at a constant pitch in FIG. 7, and the connecting portions 5 are fitted into the lower side of the circuit board 1 to be connected. The lower side of the circuit board 1 is sandwiched between the piece 8 and the sandwiching piece 9, and the connecting piece 8 is connected to the lead electrode by the solder a. The circuit board 1 to which the lead terminals are attached in this manner is erected on the mother circuit board b.
The tip portion of the leg portion 10 is soldered to the land electrode formed on the surface. At this time, the leg portion 10 of the lead terminal is
Since the circuit boards 1 are alternately projected from both sides of the circuit board 1 and function as legs for holding the circuit board 1, the circuit board 1 can stand on the mother circuit board b. As a result, the circuit board 1 is mounted in a state of standing on the mother circuit board b. Figure 7
In FIG. 2, reference numeral “2” indicates a circuit component mounted on the circuit board 1. Such a gull wing type lead terminal is
The SIL hybrid integrated circuit device can be mounted on the mother circuit board b in a low posture, which has the advantage that the circuit device can be downsized.

[0004]

The circuit board having the gull wing type lead terminals as described above has a narrow lead pitch due to the high density and miniaturization of the hybrid integrated circuit device, and the side edge of the circuit board. Soldered at a narrow pitch. When such a circuit board 1 is mounted on the mother circuit board b and the tips of the leg portions 10 of the lead terminals are soldered to the land electrodes of the mother circuit board b, one of the main surfaces on which the mother circuit board b is soldered The heat applied to the side causes the mother circuit board b to warp, for example, as shown by the chain double-dashed line in FIG. 7. Therefore, the leg portions 10 of the lead terminals are soldered to the land electrodes with the mother circuit board b warped in this way. When the mother circuit board b is cooled to room temperature after the soldering is completed, the warp is restored and the mother circuit board b returns to a flat state. The restoring force at this time extends to the lead terminals soldered to the land electrodes and causes stress to the connecting pieces 8 soldered to the lead electrodes of the circuit board 1. Therefore, the connecting portion 5 of the lead electrode may be disconnected from the lead electrode of the circuit board 1 and broken. The present invention has been made in view of such problems in the conventional lead terminal, and an object thereof is to provide a lead terminal capable of reducing disconnection of the lead terminal in a soldering process.

[0005]

In the present invention, in order to achieve the above object, the position where the leg portion 20 is led out from the connecting piece 18 is reviewed. That is, in the conventional lead terminal as described above, the strip-shaped conductor is bent to form the lead terminal. Therefore, as shown in FIG. 7, the leg portion 10 has the upper end portion of the connection piece 8. Was derived from. On the other hand, in the lead terminal according to the present invention, the leg portion 20 is led out from the intermediate portion of the connecting piece 18.

That is, the lead terminal for a circuit board according to the present invention is formed of a conductive plate-like member, and is electrically conductively fixed to the lead electrodes 13, 13 ... Formed in the vicinity of the lower side of the circuit board 11 on which the circuit is formed. Connecting piece 18 and a connecting piece 18 that is pulled out from the connecting piece 18 and extends below the connecting piece 15.
It has a leg portion 20 whose tip is conductively fixed to the land electrode on the mother circuit board b. The leg portion 20 is drawn out from the intermediate portion of the connecting piece 18.

Here, generally, the lead terminal has a holding piece 19 which is bent so that the connecting portion 15, which is the end thereof, has a concave shape on the side surface, and thereby faces the connecting piece 18. Further, it does not have such a holding piece 19,
There are those in which the holding piece 18 is formed by bending so as to have an L-shape on the side surface, and some are made of a flat conductor. On the other hand, the leg portion 20 is formed by bending so as to have a side crank shape, and its tip is oriented in a direction orthogonal to the sandwiching piece 18. Before being attached to the circuit board 1, these lead terminals are arranged in a comb-teeth shape such that the tip end side of the leg portion 20 is continuous with the lead frame 16 and the pitch thereof is the pitch of the lead electrodes 13 of the circuit board 11. Of 2
Double is appropriate.

As described above, when the tips of the leg portions 5 and 15 of the lead terminals attached to the circuit board 1 are soldered to the land electrodes of the mother circuit board b, the lead is caused by the warp of the mother circuit board b and its restoration. The external force applied to the terminal is leg 1
It acts on the origin of derivation of 0 and 20. Therefore, in the above-described conventional lead terminal, the bent portion which is the boundary between the connection piece 8 and the leg portion 10, that is, the upper end portion of the connection piece 8 is indicated by A in FIG.
The above-mentioned external force acts on the point. Therefore, this external force
The stress concentrates only on the upper end of the connection piece 8 fixed to the land electrode with the solder a, and the upper end of the connection piece 8 is relatively easily peeled off from the land electrode of the circuit board 1.

On the other hand, in the lead terminal according to the present invention,
Since the leg portion 20 is led out from the intermediate portion of the connection piece 18 of the connection portion 15, the external force applied to the lead terminal is caused by the warp of the mother circuit board b during soldering and its restoration.
8 acts on the point B in FIG. Therefore, the stress generated in the connecting piece 18 by this external force is dispersed up and down the connecting piece 18, and is not concentrated in one place. This prevents the connection piece 18 from being easily peeled off from the land electrode of the circuit board 11.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described specifically and in detail with reference to the drawings. 1 and 2 show examples of lead terminals for a circuit board according to the present invention. FIG. 1 is a state before the lead terminals are attached to the circuit board 11, and FIG. 2 is a state in which the lead terminals are attached to the circuit board 11. The state where the circuit board 1 is mounted on the mother circuit board b by the lead terminals is shown.

The lead terminal is formed by punching a plate-shaped conductor made of metal or the like having good solder wettability into a strip plate shape and bending a part of the strip-shaped conductor, and is composed of a connecting portion 15 and a leg portion 20. ing. The leg portion 15 is formed by bending the tip end side of the lead terminal into a concave shape on the side surface. By this bending, the connecting piece 18 and the sandwiching piece 19 which face each other are formed, and the distance between these connecting pieces 18 and 19 is set to be substantially the same as the thickness of the circuit board 1. The tip of the holding piece 19 at the most tip side of the lead terminal is bent outward so that the lower side of the circuit board 1 can be easily inserted into the connecting portion 15.

The leg portion 20 is connected to the connecting piece 18 on the intermediate side. The connecting piece 18 has its upper end portion completely folded down the lead terminal, and further, the intermediate portion of the connecting piece 18, that is, FIG. Hold the lead terminal at the point B as shown in
It is bent at an angle of 90 ° on the opposite side, and the leg 20 is formed at the end. The leg portion 20 is bent downward and outward by 90 ° at each of two places.
The tip portion of is oriented in a direction orthogonal to the connecting piece 18.

As shown in FIG. 1, such a lead terminal, in a state before it is attached to the circuit board 1,
The tips of the legs 20 are integrally connected to the lead frame 16, and a plurality of lead terminals are projected from the lead frame 16 in a comb tooth shape at a constant pitch. The pitch of the lead terminals arranged in the longitudinal direction of the lead frame 16 is defined by the lead terminals 13, 13 ...
Is set to twice the so-called lead pitch.
The lead frame 16 is formed with feed holes 17, 17 ... For feeding the lead frame 16 at the time of processing the lead frame 16.

The circuit board 11 to which such lead terminals are attached is formed by printing a thick film printing material such as a metal paste or a resistance paste on an insulating substrate made of, for example, ceramics or glass-epoxy resin. Fired,
It is configured by forming a predetermined wiring pattern. Then, the circuit component 12 is mounted on the circuit board 11 to form an electronic circuit. The lead electrodes 13, 13 ... Made of a conductor film are formed alternately on one main surface and the other main surface of the circuit board 1 at a constant pitch along the lower side of the circuit board 11 in FIG.

As described above, two sets of frame leads having a plurality of lead terminals projecting from the lead frame 16 are prepared, and the connecting portion 15 of one frame lead is connected to the circuit board 11.
, Which is the lower side, on which the lead electrodes 13, 13 ... Are formed. The lead terminals are lead electrodes 13, 13 ...
Since the lead frame 16 is projected at a pitch twice as large as that of
Of the ..., Only the one formed on the one main surface of the circuit board 1 is inserted, but the connection piece 18 side contacts these lead electrodes 13, 13. Further, the other frame lead is arranged such that its lead terminal faces the direction opposite to the frame lead, and the connecting portion 15 is formed on the lower side of the circuit board 11 and the remaining lead electrodes 13, 1 are formed.
3 ... Insert in the formed part. Therefore, also in this frame lead, the connecting piece 18 side is the lead electrodes 13, 13 ...
Hit

Next, the connecting piece 18 is soldered to the lead electrodes 13, 13 ... Of the circuit board 11. In FIG.
Reference numeral "a" indicates a solder for electrically connecting and fixing the connection piece 18 to the lead electrodes 13, 13, ... Of the circuit board 11 by this soldering. After that, the ends of the legs 20 are cut and the lead frame 16 is cut off. This completes the attachment of the lead terminals to the circuit board 11. The lead terminals thus mounted on the circuit board 11 are alternately mounted on both sides of the circuit board 11 as shown in FIG. 2, and the tips of the legs 20 are in a direction orthogonal to the main surface of the circuit board 11. Looking at

As shown in FIG. 2, the circuit board 11 to which the lead terminals are attached in this way is mounted on the mother circuit board b. That is, the circuit board 11 is placed on the mother circuit board b with the lead terminals facing down, and the tips of the leg portions 20 of the lead terminals are arranged on the land electrodes formed in advance on the mother circuit board b. In this state, the tips of the leg portions 20 of the lead terminals are soldered to the land electrodes on the mother circuit board b. At the time of this soldering, the circuit board b warps to the side where the land electrode to be soldered is present as shown by the chain double-dashed line in FIG. 2 due to the heat applied to the solder. b returns to a flat state as shown by the solid line. The external force applied to the lead terminal due to the warp and restoration of the circuit board acts on the point B shown in FIG. 2, so that the stress can be dispersed, and the connecting piece 18 causes the lead electrode 13 of the circuit board 11.
As described above, it is difficult to peel from the surface.

Another example of the lead terminal for a circuit board shown in FIG. 3 is one in which the holding piece 19 on the tip side which is not soldered to the lead electrode 13 of the circuit board 11 is omitted and the connecting portion 15 is formed in a side L shape. Is. From the middle of the connecting piece 18 to the leg 2
The fact that 0 is derived is the same as in the example of the lead terminal for circuit board described above.

In another example of the lead terminal for a circuit board shown in FIG. 4, the holding piece 19 which is not soldered to the lead electrode 13 of the circuit board 11 is omitted, and the bent portion on the lower end side of the connection piece 18 is also omitted. It was what I had. That is, the connecting piece 18 is composed of a flat conductor portion connected to the lead electrode 13 of the circuit board 11 and a portion which is bent from the upper end to the intermediate portion side and overlapped. The leg 20 is led out from the intermediate portion of the connecting piece 18, as in the above-described example of the lead terminal for circuit board.

Further, in the example of the lead terminal for the circuit board shown in FIG. 5, the middle of the connecting piece 18 is formed without bending the connecting piece 18 of the connecting portion 15 of the lead terminal and pulling out the leg portion 20 from the middle portion thereof. The leg portion 20 is directly and integrally led from the portion. Such a lead terminal cannot be made by simply bending a single plate material, but since the leg portion 20 is directly led out from the intermediate portion of the connecting piece 18,
Excellent stress dispersion effect.

[0020]

EXAMPLES Next, examples of the present invention will be specifically described. (Example 1) The circuit board 11 has a thickness of 0.6 mm and a width of 4
Alumina substrate of 3mm in height and 11mm in height was used, and 18 pitches were alternated on both main surfaces along the lower side with a pitch of 1.27mm.
The individual lead electrodes 13 were formed. On the other hand, using the lead terminals having the shapes shown in FIGS. 1 and 2, the connecting portion 15 was inserted into the lower side of the circuit board 11 and the connecting pieces 18 were soldered to the lead electrodes 13 as described above. It should be noted that this lead terminal has a dimension H = 2.1 mm and a dimension h shown in FIG.
= 1.3 mm.

This circuit board 11 was mounted on the mother circuit board b as described above, and the tip of the connecting piece 18 of the lead terminal was soldered to the land electrode thereof. After that, with the mounted circuit board 11 side facing downward, the mother circuit board b is mounted on the fulcrum c with a spacing of 90 mm, and the mother circuit board b is pushed by the pin d from the top surface to the center where the circuit board 11 is mounted. The part was bent by 2 mm. Then, the load was removed from the mother circuit board b to restore the bending, and a continuity test between the lead terminals and the lead electrodes of the circuit board 11 was performed. The circuit board 11 is mounted on the fulcrum c so as to cause bending in the main surface direction and the thickness direction, and FIG. 6 shows a state in which the bending occurs in the thickness direction. As a result, 2
No conduction failure occurred in all the lead terminals of the zero circuit boards.

(Embodiment 2) As in Embodiment 1, except that the lead terminals shown in FIG. 3 are soldered to the lead electrodes 13 of the circuit board 11, bending of the mother circuit board b is caused. A continuity test between the lead terminal and the lead electrode of the circuit board 11 was conducted. As a result, no conduction failure occurred in all the lead terminals of the 20 circuit boards. In addition,
The dimensions H and h shown in FIG. 3 are the same as those shown in FIG.

(Embodiment 3) As in Embodiment 1, except that the lead terminals shown in FIG. 4 are soldered to the lead electrodes 13 of the circuit board 11, bending of the mother circuit board b is performed. A continuity test between the lead terminal and the lead electrode of the circuit board 11 was conducted. As a result, no conduction failure occurred in all the lead terminals of the 20 circuit boards. In addition,
The dimensions H and h shown in FIG. 4 are the same as those shown in FIG.

(Embodiment 4) As in Embodiment 1, except that the lead terminals shown in FIG. 5 are soldered to the lead electrodes 13 of the circuit board 11, the mother circuit board b is bent. A continuity test between the lead terminal and the lead electrode of the circuit board 11 was conducted. As a result, no conduction failure occurred in all the lead terminals of the 20 circuit boards. In addition,
The dimensions H and h shown in FIG. 5 are the same as those shown in FIG.

(Comparative Example) A lead due to bending of the mother circuit board b was carried out in the same manner as in Example 1 except that the lead terminals shown in FIG. 7 were soldered to the lead electrodes 13 of the circuit board 11 as shown in FIG. A continuity test between the terminals and the lead electrodes of the circuit board 11 was conducted. As a result, defective conduction was found in the lead terminals of 5 of the 20 circuit boards.

[0026]

As described above, according to the present invention, when the circuit board 11 is mounted on the mother circuit board b and the lead terminal is soldered to the land electrode, the lead terminal and the lead electrode 13 are fixed to each other. The stress generated in a part can be dispersed without being concentrated in a specific part. As a result, it is possible to prevent a trouble in which the lead terminal comes off from the lead electrode of the circuit board 11, prevent a conduction failure of the lead terminal, and improve the yield.

[Brief description of drawings]

FIG. 1 is a partial perspective view showing an example of a lead terminal for a circuit board and a circuit board to which the lead terminal is attached according to the present invention before being attached.

FIG. 2 is a partial front view of an example in which a lead terminal for a circuit board according to the present invention is attached to a circuit board, and the circuit board is mounted on a mother circuit board.

FIG. 3 is a partial front view of another example in which the lead terminal for a circuit board according to the present invention is attached to the circuit board, and the circuit board is further mounted on the mother circuit board.

FIG. 4 is a partial front view of another example in which the lead terminal for a circuit board according to the present invention is attached to the circuit board, and the circuit board is further mounted on the mother circuit board.

FIG. 5 is a partial front view of another example in which the lead terminal for a circuit board according to the present invention is attached to the circuit board, and the circuit board is further mounted on the mother circuit board.

FIG. 6 is a partial front view showing a test method of a circuit board having lead terminals for a circuit board according to the present invention mounted on a mother circuit board.

FIG. 7: Attach the lead terminals for the circuit board to the circuit board,
Further, it is a partial front view of a conventional example in which this circuit board is mounted on a mother circuit board.

[Explanation of symbols]

 11 circuit board 12 circuit component 13 lead electrode 15 connecting part 16 lead frame 18 connecting piece 19 sandwiching piece 20 leg a solder b mother circuit board

Claims (6)

[Claims] 1. A connecting piece formed of a conductive plate-like member and conductively fixed to lead electrodes (13), (13) ... Formed in the vicinity of the lower side of a circuit board (11) on which a circuit is formed. (18) and a leg portion (20) which is pulled out from the connecting piece (18) and extends downward from the connecting piece (18) and whose tip is conductively fixed to the land electrode on the mother circuit board (b). In the lead terminal for the circuit board, the leg portion (20)
Is led out from the intermediate portion of the connection piece (18). 2. A holding piece (19) facing the connection piece (18) by bending the tip of the lead terminal so as to have a concave shape on the side surface. The lead terminal for a circuit board according to. 3. The lead terminal for a circuit board according to claim 1, wherein the connection piece (18) is formed by bending the side surface to have an L shape. 4. The connection piece (15) is made of a flat conductor which is electrically conductively fixed to the lead electrodes (13), (13) ... Of the circuit board (11). Circuit board lead terminals. 5. The lead terminal for a circuit board according to claim 1, wherein the leg portion (20) is bent and formed to have a side crank shape. 6. The leg portions (20) are connected to the lead frame (16) at their tip ends, and lead terminals are arranged in parallel at a pitch twice the pitch of the lead electrodes (13) of the circuit board (11). A lead terminal for a circuit board, which is characterized in that