JP3502773B2 - Lead frame and lead frame joining jig - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention joins a plurality of lead terminals to a wiring board such as a package for storing electronic parts or a multilayer wiring board while preventing the positional displacement due to the difference in thermal expansion during brazing. The present invention relates to a lead frame and a jig for joining the lead frame.

[0002]

2. Description of the Related Art A package for storing electronic components for storing various electronic components such as semiconductor elements or a wiring board such as a multilayer wiring board on which these electronic components are mounted has a large amount of external electrical circuits. For the input and output of information
A plurality of lead terminals are joined to one side or the periphery of the substrate. The plurality of lead terminals are arranged adjacent to each other in parallel with each other, and a joint portion set at one end thereof is joined to the wiring board to be electrically connected to the electronic component in the wiring board and the other end portion Is electrically connected to an external electric circuit. As a result, various electric signals are input / output between the wiring board and the external electric circuit.

In order to bond such a plurality of parallel lead terminals to the wiring board, conventionally, for example, one end portion on the side where the connection part with the wiring board is set as shown in a plan view of FIG. Lead terminals 1 arranged in parallel with each other aligned
The lead frame 3 is composed of a plurality of lead terminals 1 and the other ends of the lead terminals 1, which are commonly connected to each other, and a band-shaped connecting member 2 which is integrally formed in a direction perpendicular to the lead terminals 1. Has been. Such a lead frame 3
Are usually made of alloys such as Fe-Ni alloys such as 42 alloy or Fe-Ni-Co alloys such as Kovar (registered trademark).

Further, such a conventional lead frame 3 is used.
When the lead terminal 1 is joined to the wiring board, the joining is generally performed by brazing. For example, as shown in a perspective view of FIG. 5, this joining is performed by using a brazing filler metal (not shown) between the lead terminals 1 of the lead frame 3 and the wiring substrate 4 and joining them with each other with a heat resistant material such as carbon. By placing it on a bonding jig 5 made of a conductive material, heating it to a temperature at which the brazing material melts, and brazing the bonding part of each lead terminal 1 of the lead frame 3 and the bonding part of the wiring board 4 to each other. Has been done.

As shown in FIG. 5, the joining jig 5 is mounted so that the wiring board 4 is fitted into the board mounting recess 6 and the lead frame 3 is fitted therein. The lead frame mounting recessed portion 7 formed of a recessed portion is formed. A plurality of parallel lead terminals 1 are fitted in the lead frame mounting recesses 7, and a lead terminal fitting portion for holding them and positioning them in the left-right direction (direction perpendicular to the lead terminals 1) with respect to the wiring board 4. 7a and the connecting member 2 are fitted, and the connecting member fitting portion 7 for holding and positioning the lead terminal 1 with respect to the wiring board 4 in the front-back direction (the direction parallel to the lead terminal 1).
b and are provided.

[0006]

[SUMMARY OF THE INVENTION However, such according to the conventional lead frame 3 and the lead frame bonding jig 5, the lead frame 3 is made of alloy thermal expansion coefficient of about 11 to 13 × 10 ^{- 6} / ° C, which is large, the joining jig 5 is made of carbon, etc.
Since it is as small as about 1/2 at 10 ⁻⁶ / ° C., after joining the lead frame 3 and the wiring board 4 by brazing,
There is a problem that a stress due to a difference in thermal expansion is applied to the joint, which lowers the joint strength or causes a defect such as a crack in the joint.

That is, when the joint portion between the lead frame 3 and the wiring board is positioned by the joint jig 5 and then the brazing filler metal is heated to melt and braze, the lead frame 3 has a coefficient of thermal expansion. Jig 5
In the state where the lead terminal 1 is extended on the lead frame mounting concave portion 7 of the substrate mounting concave portion 6 and the connecting member fitting portion 7b, the lead terminal 1 is extended more than the original distance between the joint portion and the connecting member fitting portion 7b. 7b will be positioned and brazed. Then, when the lead material 3 and the wiring board are brazed by cooling to solidify the brazing material and then cooled to room temperature, the lead terminals 1 of the lead frame 3
Shrinks and tends to become shorter than the original distance between the joint on the substrate mounting recess 6 and the connecting member fitting portion 7b.
Since the connecting member 2 is held by the connecting member fitting portion 7b, the lead terminal 1 applies tensile stress to the joint between the lead terminal 1 and the wiring board. As a result, due to the stress caused by the difference in thermal expansion, the lead terminal 1 and the connecting member 2 are deformed such as warped or bent, or the joint strength of the joint is reduced, or the joint of the wiring board is damaged. It causes problems such as cracks,
There is a problem that the reliability of the joint is lowered.

The present invention has been devised in view of such conventional problems, and an object thereof is to apply a stress due to thermal expansion of a lead terminal to a joint portion even after joining by brazing with a wiring board. To provide a lead frame and a bonding jig for the lead frame, which are excellent in the reliability of the bonding portion, without the deformation of the lead terminal or the connecting member, the deterioration of the bonding strength, and the occurrence of defects such as cracks in the bonding portion. is there.

[0009]

A lead frame according to the present invention comprises a plurality of parallel lead terminals whose tips of joints with a wiring board are aligned, and auxiliary lead members which are arranged in parallel on both sides of the plurality of lead terminals. Are integrally connected by a band-shaped connecting member, and a hooking portion is provided at a position facing the joining portion of the auxiliary lead member, and the hooking portion is provided between the auxiliary lead member and the lead terminal adjacent to the auxiliary lead member. The gap is larger than the gap between the lead terminals.

Further, the lead frame joining jig of the present invention is a lead frame joining jig for joining the lead frame of the present invention and the wiring board having the above-mentioned constitution, and the wiring board is placed on the jig. And a lead frame mounting recess on which the lead frame is mounted,
The lead frame mounting recess has a plurality of lead terminals and a connecting member fitted therein, and a lead terminal fitting portion and a connecting member fitting portion for aligning a joint portion of the lead terminal with a wiring board in a direction perpendicular to the lead terminal. An auxiliary lead member fitting portion provided with a jig side hooking portion in which the auxiliary lead member is fitted and engages with the hooking portion to align the joint portion of the lead terminal with the wiring board in a direction parallel to the lead terminal. It is characterized by consisting of.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, a lead frame and a jig for joining lead frames according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a plan view showing an example of an embodiment of a lead frame of the present invention. FIG. 2 is a perspective view showing an example of an embodiment of the lead frame and the lead frame joining jig of the present invention. Similar to FIG. 5, FIG. 2 shows how the lead frame shown in FIG. 1 is used to join the wiring board.

In these figures, 11 is a lead terminal and 12 is a lead terminal.
Is a strip-shaped connecting member. The plurality of lead terminals 11 are arranged adjacent to each other in parallel so that the ends of the joints 11a with the wiring board set at one end thereof are aligned, and the other end is commonly integrated with the connecting member 12. It is connected. The lead terminals 11 have a required terminal width and are arranged at required intervals. The joint portion 11a of the lead terminal 11 is usually set at the end of the lead terminal 11, but it may be provided at a position slightly away from the connecting member 12 of the lead terminal 11 depending on the specification of the joint with the wiring board. Further, the connecting member 12 is usually arranged in a direction perpendicular to the lead terminal 11 and is integrally formed.

Auxiliary lead members 13 are connected to the connecting member 12 on the outer side of the outermost lead terminal 11, that is, on both sides of the plurality of lead terminals 11, and are integrally formed. The auxiliary lead member 13 is parallel to the lead terminal 11 and has a hook portion 14 at a position facing the joint portion 11a of the lead terminal 11, that is, at a position substantially side by side with the joint portion 11a. In this example, the hooking portion 14 is formed as a protruding portion that protrudes from the tip of the auxiliary lead member 13 to the side opposite to the lead terminal 11.

The lead frame 15 of the present invention is constituted by such a plurality of parallel lead terminals 11, the connecting member 12 and the auxiliary lead member 13 provided with the hook portion 14.

The lead frame 15 of the present invention as described above is
Usually, it is made of an alloy such as Fe-Ni alloy such as 42 alloy or Fe-Ni-Co alloy such as Kovar (registered trademark). Further, the production is performed by subjecting the flat metal thin plate to a mechanical working method such as press working or a chemical working method such as etching. At this time,
The lead terminal 11 and the auxiliary lead member 13 are made of the same material, and the length from the connecting member 12 to the joint portion 11a and the hook portion
It is formed so that the length up to 14 is almost the same. As a result, as will be described later, it is possible to obtain a highly reliable joint portion in which adverse effects on the joint portion due to thermal expansion of the lead terminal 11 during brazing are eliminated.

In order to join the lead terminals 11 of the lead frame 15 of the present invention to the wiring board, the joining by brazing is performed as in the conventional case. That is, as shown in the perspective view of FIG. 2, a brazing filler metal (not shown) is interposed between the lead terminals 11 of the lead frame 15 and the wiring board 16 so that the heat resistant material such as carbon is used. It is placed on the lead frame joining jig 17 of the present invention, heated to a temperature at which the brazing material melts, and the joining portions 11a of the lead terminals 11 of the lead frame 15 and the joining portion of the wiring board 16 are brazed. To do.

Here, as shown in FIG. 2, the lead frame joining jig 17 of the present invention is provided with a board mounting recess 18 which is a recess for mounting the wiring board 16 therein, and a lead frame. A lead frame mounting recess 19 is formed, which is a recess in which 15 is mounted.
The lead frame mounting recess 19 is formed of a lead terminal fitting portion 20, a connecting member fitting portion 21, and an auxiliary lead member fitting portion 22.

The lead terminal fitting portion 20 and the connecting member fitting portion 21 are fitted with the plurality of lead terminals 11 and the connecting member 12, and the joint portion 11a of the lead terminal 11 is arranged in the left-right direction (to the lead terminal 11) with respect to the wiring board 16. It is for alignment in the vertical direction).

Further, the auxiliary lead member fitting portion 22 is fitted with the auxiliary lead member 13, and the joining portion 11 of the lead terminal 11 is joined.
a is to be aligned with the wiring board 16 in the front-rear direction (the direction parallel to the lead terminals 11). Therefore, the auxiliary lead member fitting portion 22 is provided with the auxiliary lead member 13a.
A jig-side hooking portion 23 is provided which engages with the hooking portion 14 and performs positioning by the hooking portion 14.

According to the lead frame 15 of the present invention, the auxiliary lead members 13 arranged parallel to the lead terminals 11 are provided on both sides of the plurality of parallel lead terminals 11, and the lead terminals 11 are joined to the respective auxiliary lead members 13. Since the hook portion 14 is provided so as to face the position of the portion 11a, this hook portion 14
Thus, the joint portion 11a of the lead terminal 11 and the joint portion of the wiring board 16 can be positioned in the front-rear direction, that is, in the direction parallel to the lead terminal 11. for that reason,
When the lead terminal 11 and the wiring board 16 are joined by brazing, it is not necessary to use the connecting member 12 for positioning in the front-rear direction, and the lead terminal 11 and the connecting member 12 are connected to each other.
It can be positioned so that it can freely expand and contract and move in a direction parallel to. Therefore, even if the lead terminal 11 expands and contracts due to heating and cooling during brazing, the lead terminal 11 and the connecting member 12 can freely expand and contract with respect to the wiring board 16, and thus the wiring board 16 and No stress is applied to the joint part of.

Further, the lead frame joining jig of the present invention
According to 17, as a jig for joining the lead frame 15 of the present invention having the above-described configuration to the wiring board 16, the joining portions 11a of the plurality of parallel lead terminals 11 are perpendicular to the lead board 11 with respect to the wiring board 16. In this direction, the lead terminal fitting portion 20 and the connecting member fitting portion 21 are used for alignment. In the direction parallel to the lead terminal 11, the hook portion 14 is used to align the joint portion 11a of the lead terminal 11 on the jig side. Since the auxiliary lead member fitting portion 22 provided with the hook portion 23 has the lead frame mounting concave portion 19 which is formed by the fitting portion 22, when the lead terminal 11 and the wiring board 16 are joined by brazing, the lead terminal 11 and the connecting member 12 can be positioned so that they can freely expand and contract in the direction parallel to the lead terminal 11 and move. Therefore, even if the lead terminal 11 expands and contracts due to heating and cooling during brazing, the lead terminal 11 and the connecting member 12 can be connected to the wiring board.
Since it can be freely expanded and contracted with respect to 16 and can be moved, good brazing and joining can be performed without stress being applied to the joint with the wiring board 16.

Therefore, according to the lead frame and the jig for joining the lead frame of the present invention, the stress caused by the thermal expansion of the lead terminal is not applied to the joint portion even after the joint with the wiring substrate by brazing, The terminals and the connecting members are not deformed, the joint strength is lowered, and cracks and the like are not generated in the joints, and the joints can be joined with excellent reliability.

It goes without saying that the lead frame and the jig for joining the lead frame of the present invention can take various suitable forms according to the specifications of the wiring board to which the lead frame is joined. Further, the hook portion of the auxiliary lead member and the jig-side hook portion of the auxiliary lead member fitting portion may also be provided inside the auxiliary lead member, that is, on the lead terminal side of the lead frame. Various forms can be adopted in consideration of the specifications of the wiring board and the ease of processing the lead frame.

Another example of such a hook portion of the auxiliary lead member and a jig side hook portion of the auxiliary lead member fitting portion is shown in FIG.

3 (a) to 3 (c) respectively show the hook portion 14 of the auxiliary lead member 13 and the jig side hook portion 23 of the auxiliary lead member fitting portion 22 in the lead frame and the lead frame joining jig of the present invention. It is a principal part perspective view which shows the other example.

In the example shown in FIG. 3A, the auxiliary lead member 13 is formed with a notch-shaped hook portion 14-1 and the auxiliary lead member engages with the hook portion 14-1 on the side surface of the fitting portion 22. A jig-side hooking portion 23-1 in the form of an overhanging portion is provided.

Further, in the example shown in FIG. 3B, the hook portion 14-2 is formed in the auxiliary lead member 13 by a through hole, and the hook portion 14-2 is formed on the side surface of the auxiliary lead member fitting portion 22.
Cylindrical (pin-shaped) jig side hooking part 23-2
Is provided.

Further, in the example shown in FIG. 3C, the hook portion 14 is formed by bending the tip of the auxiliary lead member 13.
-3 is formed on the bottom surface of the auxiliary lead member fitting portion 22, and the groove-like jig-side hook portion 23 engages with the hook portion 14-3.
-3 is provided.

According to the hooking portions 14-1 to 14-3 and the jig-side hooking portions 23-1 to 23-3 shown in FIGS. 3A to 3C, the hooking portions 14-1 to 14-3 shown in FIGS. Compared with the hooking portion 14 and the jig-side hooking portion 23, the lead frame and the lead frame joining jig can be made narrower in total width, which is advantageous for downsizing.

In addition to this, the notch-shaped hooking portion 14-1 may have a semicircular or triangular shape, or the hooking portion 14-2 formed by a through hole may have a semicircular, quadrangular or triangular shape. Alternatively, the hooking portion 14-3 formed by bending may be formed in a semicircular shape or a triangular shape, and the jig-side hooking portions 14-1 to 14-3 that engage with the hooking portions 14-3 may have corresponding shapes.

Further, the auxiliary lead member 13 is not limited to the elongated plate shape similar to the lead terminal 11, but may be a prismatic shape, a cylindrical shape, an L-shape,
It may be used as a reinforcing member in various sectional shapes such as a U-shape.

[0033]

Example A wiring board was prepared in which an insulating substrate made of an aluminum oxide sintered body was formed with a joint made of a refractory metal such as molybdenum or tungsten. This joint was formed on one end of the insulating substrate with a width of 0.8 mm and a depth of 1.0 mm. Also, in order to ensure the wettability of the brazing filler metal at the time of joining with the lead frame, nickel and gold plating layers with a thickness of 10 μm and 1 μm, respectively, are applied to the surface of the refractory metal. Formed.

On the other hand, the lead frame of the present invention having the shape shown in FIG. 1 is formed by a lead frame having a thickness of 0.15 mm and a lead terminal length of 20 mm and a lead frame having a thickness of 0.2 mm and a lead terminal length of 30 mm, respectively. A frame and the conventional lead frame shown in FIG. 4 were prepared. As a result, four types of lead frames were prepared depending on the combination of size and shape.

Next, the wiring board was placed on the carbon jigs of the present invention and the conventional one prepared according to the size and shape of each lead frame, and then each of the four kinds of lead frames was bonded to the joint with 28 wt% of silver. -The copper brazing material foil was sandwiched and placed, and heated to a temperature of 850 ° C in a reducing atmosphere to bond the wiring board and the lead frame. The length of the joint portion was 0.6 mm.

When the warped state of the lead frame after joining was visually confirmed, the results shown in Table 1 were obtained.

[0037]

[Table 1]

As shown in Table 1, the sample No. 1 by the lead frame and the jig for joining the lead frame of the present invention was used.
No warpage was observed in ・ 3, whereas warpage was confirmed in Sample Nos. 2 and 4 by the conventional lead frame and lead frame joining jig. From this, according to the lead frame and the jig for joining the lead frame of the present invention, when the lead frame is joined to the wiring board, stress due to the difference in the thermal expansion coefficient is not applied to the joint portion, It was confirmed that the lead frame did not warp.

Further, when the bonding strength between the wiring board and the lead frame was measured for these sample numbers 1 to 4,
The results are shown in Table 2.

Here, the bonding strength was measured as follows. First, the connecting member of the lead frame after joining was cut and removed, and the end portion of the lead terminal not joined to the wiring board was set as a free end portion, and this free end portion was bent perpendicularly to the joining portion. Next, this free end was fixed to a tensile tester and pulled up at a speed of 1 mm / min, and the maximum value of stress when the lead frame was peeled from the joint was recorded. For each sample, 10
A book lead terminal was used.

[0041]

[Table 2]

As shown in Table 2, in the samples 1 and 3 using the lead frame of the present invention, the bonding strength exceeding 3 kg was obtained, whereas in the sample 2 using the conventional lead frame,
In No. 4, only a joining strength of 3 kg or less was obtained. From this, according to the lead frame and the jig for joining the lead frame of the present invention, when the lead frame is joined to the wiring board, stress due to the difference in thermal expansion coefficient is not applied to the joint portion, It was confirmed that the bonding strength between the lead frame and the wiring board after bonding did not decrease.

The present invention is not limited to the examples of the above embodiments, and various modifications and improvements can be made without departing from the gist of the present invention. For example, the position of the hook formed on the auxiliary lead member is
According to the specifications of the product to which the lead frame of the present invention is applied, the lead frame is displaced in the front-back direction parallel to the lead terminal as a vicinity of the position facing the joint of the lead terminal within a range not deviating from the intended effect of the present invention. May be Also,
In order to join a plurality of lead frames of the present invention to a plurality of wiring boards at once, a plurality of lead frames in which a plurality of lead frames of the present invention are connected by connecting members by extending a belt-like connecting member It may be a lead frame having a group.

[0044]

According to the lead frame of the present invention, a plurality of parallel lead terminals and auxiliary lead members arranged on both sides thereof in parallel with the lead terminals are integrally connected by a belt-like connecting member, and Since the auxiliary lead member is provided with a hook portion so as to face the position of the lead terminal joint portion, the hook portion can position the lead terminal joint portion and the wiring board in a direction parallel to the lead terminal. it can. Therefore, when the lead terminal and the wiring board are joined by brazing, the lead terminal and the connecting member can be positioned such that they freely expand and contract in the direction parallel to the lead terminal and move. Even if the lead terminal expands and contracts due to heating and cooling at the time, the lead terminal and the connecting member can freely expand and contract with respect to the wiring board, so that no stress is applied to the joint with the wiring board. .

Further, according to the lead frame joining jig of the present invention, as a jig for joining the lead frame of the present invention to the wiring board, the joining portions of a plurality of parallel lead terminals are connected to the wiring board. Positioning in the direction perpendicular to the lead terminal is performed by the lead terminal fitting part and the connecting member fitting part, and the auxiliary lead member provided with a jig side hooking part that uses the hooking part to align in the direction parallel to the lead terminal. Since the lead frame mounting recess is formed by the fitting portion, the lead terminal and the connecting member can be freely moved in the direction parallel to the lead terminal when the lead terminal and the wiring board are joined by brazing. It can be positioned so that it expands and contracts and moves, and the lead terminal expands and contracts due to heating and cooling during brazing. Since the lead terminals and the connecting member be capable of moving to freely expand and contract with respect to the wiring board, there is no stress may be applied to the joint portion of the wiring substrate, it is possible to good brazing.

As described above, according to the present invention, the stress due to the thermal expansion of the lead terminal is not applied to the joint even after the brazing with the wiring board, and the deformation / joint strength of the lead terminal and the connecting member is prevented. It was possible to provide a lead frame and a lead frame bonding jig that can perform bonding with excellent reliability of the bonding portion without deterioration of the thickness and generation of defects such as cracks in the bonding portion.

[Brief description of drawings]

FIG. 1 is a plan view showing an example of an embodiment of a lead frame of the present invention.

FIG. 2 is a perspective view showing an example of an embodiment of a lead frame and a jig for joining lead frames of the present invention.

3 (a) to 3 (c) are perspective views of a main part showing another example of the embodiment of the hook portion of the lead frame and the jig side hook portion of the lead frame joining jig of the present invention, respectively. is there.

FIG. 4 is a plan view showing an example of a conventional lead frame.

FIG. 5 is a perspective view showing an example of a conventional lead frame and a jig for joining lead frames.

[Explanation of symbols]

11 --- Lead terminal 11a ・ ・ ・ ・ ・ ・ ・ Joining part 12 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Connecting members 13 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Auxiliary lead member 14, 14-1, 14-2, 14-3 ... Hook 15 --- Lead frame 16 ・ ・ ・ ・ ・ ・ ・ ・ Wiring board 17 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Jigs for joining lead frames 18 ... 19 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Lead frame mounting recess 20 ・ ・ ・ ・ ・ ・ ・ Lead terminal fitting part 21 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Connecting member fitting part 22 ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Auxiliary lead member fitting part 23, 23-1, 23-2, 23-3 ... Jig side hook

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jun Terada 1 at 10 Kawai, Gamo-cho, Gamo-gun, Gaga-gun, Shiga factory, Kyocera Corporation (56) Reference JP-A-60-83358 (JP, A) 59-172254 (JP, A) JP-A-6-69396 (JP, A) JP-A-6-53395 (JP, A) Actually open 3-96051 (JP, U) JP-B-51-8783 (JP , B1) (58) Fields investigated (Int.Cl. ⁷ , DB name) H01L 23/50

Claims (2)

(57) [Claims] 1. A plurality of parallel lead terminals whose tips of joints with a wiring board are aligned and auxiliary lead members arranged in parallel on both sides of the plurality of lead terminals are integrally connected by a belt-like connecting member. and it made it, and provided with a hook portion at a position facing to the junction of the auxiliary lead member, before
Of the auxiliary lead member and the lead terminal adjacent thereto
The lead frame is characterized in that an interval between the lead terminals is larger than an interval between the lead terminals . 2. A lead frame joining jig for joining the lead frame according to claim 1 and a wiring board, wherein the board placing recess on which the wiring board is placed and the lead frame are placed. A lead frame mounting recess to be placed, the lead frame mounting recess is fitted with a plurality of lead terminals and a connecting member, and a joint portion of the lead terminals is arranged in a direction perpendicular to the lead terminals with respect to the wiring board. The lead terminal fitting portion and the connecting member fitting portion to be aligned with the auxiliary lead member are fitted and engaged with the hook portion to align the joint portion of the lead terminal with the wiring board in a direction parallel to the lead terminal. A lead frame joining jig comprising an auxiliary lead member fitting portion provided with a tool-side hooking portion.