JP3065240B2 - Heat treatment method for continuous lead frame for electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heat-treating a continuous lead frame for an electronic component, and more particularly, to a step of producing a thin metal plate as a material of a continuous lead frame for an electronic component and / or a thin metal plate. An electronic component lead for removing internal residual stress and / or residual strain remaining in the continuum, which is generated in a punch forming step of punching or etching a lead frame for an electronic component at a constant pitch to form a continuum. The present invention relates to a heat treatment method for a frame continuous body.

[0002]

2. Description of the Related Art For example, in the case of a semiconductor device, its high density,
With high integration, when forming a continuum of semiconductor device lead frames by punching a thin metal plate at a constant pitch, if the spacing between adjacent inner leads is extremely narrow, deformation of the inner leads due to reduced strength during punching As a result, there is a case where the very fine tips are short-circuited. Therefore, in order to prevent this short circuit, in a state where the tips of the inner leads are connected with the connecting pieces in advance,
There is known a method in which a lead frame for a semiconductor device is stamped and formed, and then a continuous body is annealed in an annealing furnace, and then a connecting piece is cut off in a predetermined process.

[0003]

However, if the semiconductor device lead frame is punched out in such a state that the tips of the inner leads are connected by the connecting pieces, a short circuit between the tips of the inner leads after punching is obtained. However, due to the internal residual stress and / or residual strain retained in the continuum, after cutting off the connecting piece after annealing, deformation such as torsion caused by press working at the tip of the inner lead remains, and the wire There is a possibility that inconveniences such as lowering the bonding predictive ratio may occur. This is the same when forming a lead frame for electronic parts by etching. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a heat treatment method for a continuous lead frame for electronic components, which can remove internal residual stress and / or residual strain remaining in the continuous body.

[0004]

According to the present invention, there is provided a semiconductor device comprising:
The heat treatment method for a continuous lead frame for an electronic component according to the aspect of the invention includes a method for heat treating the continuous lead frame for an electronic component having a plurality of connection terminals whose tips are connected by connecting pieces. A method for heat-treating a continuous lead frame for an electronic component, wherein the residual strain is removed by heating while the continuous body passes through an annealing furnace, wherein the continuous strain is disposed on a front side and a back side of a continuous body transfer path in the annealing furnace. A plurality of pairs of the transfer-type table, the back surface pressing plate, the front surface of each of the single electronic component lead frame, in a state where the back surface is individually pressed, the continuous body and each pair arranged table, the back surface pressing plate By synchronously transferring along the continuum transfer path,
The internal residual stress and / or residual strain of the electronic component lead frame is continuously removed. Here, the lead frame for an electronic component refers to a lead frame for a semiconductor device, a lead frame for a relay terminal, and the like.

According to a second aspect of the present invention, there is provided a method for heat-treating a continuous lead frame for an electronic component, wherein each of the surface pressing plates includes a mounting plate. The pair of front endless chains arranged on the front surface side of both sides of the continuous body transfer path, respectively, is laid at a predetermined pitch, and each of the back surface pressing plates, via the mounting plate, Each of the pair of back endless chains is laid horizontally at a predetermined pitch between a pair of back endless chains arranged on the back side of both sides of the continuous body transfer path. The disposed front and back pressing plates sequentially and individually press the electronic component lead frames of the continuum, and are transferred along the continuum transfer path.

Further, the heat treatment method for a continuous lead frame for electronic components according to claim 3 is the heat treatment method for a continuous lead frame for electronic components according to claim 1 or 2, wherein the front and back surfaces of the continuous body transfer path are provided. On the side, the table, each of a plurality of pairs of movable tables arranged side by side at a pitch shorter than the length of the back pressing plate in the transfer direction, the back pressing rollers,
By urging in a direction approaching each other through a plurality of elastic members, each table and back surface pressing plate being transported along the continuum transfer path, the front and rear surface pressing rollers arranged in each pair, respectively. When the intermediate time is reached, the front and rear pressing plates are individually and sequentially pressed against the front and rear surfaces of the electronic component lead frames of the continuous body during the synchronous transfer. In particular, if the interval between the front and back side pressing rollers is set to, for example, two-thirds or less of the length of the front and back pressing plates in the transport direction, each table and the back pressing plate always have two front and rear tables. ,
Each table and the back surface pressing plate that are pressed by the back surface pressing roller and are being transported can move smoothly with little vertical movement when the end in the traveling direction is sandwiched between the next table and the back surface pressing roller. .

According to a fourth aspect of the present invention, there is provided a method of heat-treating a continuous lead frame for an electronic component according to the first or second aspect. The upper and lower guide rails, which are parallel to the body transfer path and are supported by elastic support members, are arranged in pairs, and both ends of the mounting plate for the front and back pressing plates extend to the sides of the annealing furnace. Then, a running roller that rolls in contact with the upper and lower guide rails is disposed on a surface of each of the extending portions on the side away from the continuous body transfer path. Further, the heat treatment method for a continuous lead frame for electronic components according to claim 5 is the heat treatment method for a continuous lead frame for electronic components according to any one of claims 2 to 4, wherein A cleaning device for the front and back pressing plates is disposed outside the annealing furnace of the chain, and the front and back pressing plates passing through the annealing furnace are sequentially cleaned.

[0008]

In the heat treatment method for a lead frame for electronic parts according to any one of claims 1 to 5, the front and back sides of each of the lead frames for electronic parts are individually sandwiched via the respective front and back side pressing plates. Since the continuum and the front and back pressing plates are synchronously transferred along the continuum transfer path while being pressurized and constrained in the shape, each single electronic component lead frame passing through the annealing furnace is subjected to this annealing. Thereafter, by cooling, the internal residual stress and / or residual strain retained in the continuum is removed. In other words, the internal residual stress and / or residual strain of the continuum is accumulated in the continuum because the continuum is annealed to a certain temperature or higher and the unnecessary cooling is performed by the subsequent cooling. The internal residual stresses and / or residual strains that have been removed are removed. In particular, in the heat treatment method for a lead frame continuous body for electronic parts according to claim 2, the front and back sides of both sides of the continuous body transfer path, a pair of upper sides,
When the lower endless chain is rotated synchronously, the lead frames for each electronic component of the continuum are sequentially and surely individually pressed by the paired front and back surface pressing plates, and are continuously and reliably pressed into the continuum transfer path. Since they are transported along, the cost of equipment can be reduced.

According to a third aspect of the present invention, in the method for heat treating a continuous lead frame for an electronic component, the continuous body is moved between the front and rear side pressing rollers urged in the approaching direction by an elastic member. When the front and rear pressing plates pass, the front and rear pressing plates are sequentially pressed with appropriate pressing force onto the front and rear surfaces of the electronic component lead frames. Then, the continuum being transported can be inserted into a high-temperature annealing furnace with the front and back pressing plates sandwiching each electronic component lead frame held therebetween. And
In this way, the interval between the adjacent front and back side pressing rollers is
Since the pitch is shorter than the length of the front and back pressing plates in the transfer direction, each of the front and back pressing plates is constantly pressed between any of the front and back pressing rollers. The pressure-restricted state is maintained while the front and back pressing plates pass through the installation range of the front and back pressing rollers.

Further, in the heat treatment method for a continuous lead frame for an electronic component according to the fourth aspect, the traveling roller of each mounting plate is supported along the lower guide rail by being supported by the elastic supporting member in a biased state. By rolling, each table and the backside pressing plate can be smoothly transferred in the annealing furnace without moving up and down. The sandwiched state can be always maintained while the front and back pressing plates are being transferred through the continuous body transfer path of the annealing furnace. In the heat treatment method for a continuous lead frame for an electronic component according to the fifth aspect, the front and rear pressing plates that have passed through the annealing furnace are sequentially cleaned by the cleaning device, so that the electronic component lead held next. It can be circulated and reused without soiling the front and back of the frame.

[0011]

According to the heat treatment method for a continuous body of lead frames for electronic parts according to the first to fifth aspects, each lead frame for electronic parts of the continuous body being annealed in this way is formed on both sides by the corresponding front and back pressing plates. Since the continuum is transferred in the annealing furnace in a pressure-constrained state sandwiched between the continuum and the continuum, it is annealed and cooled, thereby removing the internal residual stress and / or residual strain retained in the continuum. In particular, in the heat treatment method for a continuous body of lead frames for electronic parts according to the second aspect, a chain conveyor is employed as a means for synchronously transferring the continuous body of the front and back pressing plates, so that equipment costs can be reduced.

According to a third aspect of the present invention, there is provided a method for heat treating a continuous body of lead frames for electronic parts, wherein the means for pressing the front and rear pressing plates against each electronic part lead frame of the continuous body in the annealing furnace is used. The adoption of the front and back side pressure rollers urged in the direction of proximity by the members provides a means that has relatively few failures even in a high-temperature atmosphere such as an annealing furnace and has the function at relatively low equipment cost. it can. Further, since the pitch between each adjacent table and the back side pressing roller is shorter than the length of the table and the back side pressing plate in the transport direction, each table and the back side pressing plate are always in any one of the table and the back side pressing roller. Thus, the pressure-restrained state of the lead frame for electronic components can be maintained while the front and back pressing plates pass through the installation range of the front and back pressing rollers.

Further, in the heat treatment method for a continuous body of lead frames for electronic parts according to the present invention, the front and rear pressing plates are pressed onto the continuous body transfer path while being pressed against the lead frames for electronic parts of the continuous body. As a mechanism for transferring along, an elastic furnace supported on the annealing furnace side, a lower guide rail, and a table having a front roller rolling on each of the surfaces thereof and a traveling roller on the back surface pressing plate side were adopted. Therefore, the sandwiched state of the corresponding electronic component lead frame by the front and back pressing plates of each pair can be maintained at all times while the front and back pressing plates are moving through the continuous body transfer path of the annealing furnace. Further, in the heat treatment method for a lead frame continuous body for electronic parts according to claim 5, the table after passing through the annealing furnace and the back surface pressing plate are sequentially cleaned by the cleaning device. By the back surface pressing plate, the front and back surfaces of the electronic component lead frame sandwiched next can be reused in a clean state without soiling.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the accompanying drawings to provide an understanding of the present invention. Here, FIG. 1 is a schematic configuration longitudinal sectional view of a heat treatment apparatus for a continuous lead frame for electronic components to which the heat treatment method for a continuous lead frame for electronic components according to one embodiment of the present invention is applied, and FIG. FIG. 3 is an enlarged front view of an essential part of a pressing roller, FIG. 4 is an enlarged front view of an essential part of a pressing roller, and FIG. 5 is a lead frame for an electronic component according to another embodiment of the present invention. FIG. 6 is an enlarged schematic cross-sectional view of a main part of a heat treatment apparatus for a continuous body of lead frames for electronic components used in a heat treatment method for a continuum. FIG.

As shown in FIG. 1, a heat treatment apparatus 10 for a continuous lead frame for electronic components to which a heat treatment method for a continuous lead frame for electronic components according to an embodiment of the present invention is applied is provided in an annealing furnace 11. Lead frame 13 for each single electronic component of continuum 12 transferred on continuum transfer path a
Pairs of front and back pressing plates 1 pressed individually
Front and back side chain conveyors 16 and 17 for synchronously circulating 4 and 15 from the furnace entrance and exit via upper and lower external parts
have. Here, a lead frame for a semiconductor device is adopted as the lead frame 13 for an electronic component. A large number of heaters are arranged in the annealing furnace 11. The continuous body 12 obtained by continuously punching the electronic component lead frame 13 at a constant pitch moves at a low speed along the continuous body transfer path a in the annealing furnace 11. Annealed during transfer.

As shown in FIG. 2, each of the lead frames 13 for electronic components continuously punched into the continuous body 12 is partitioned by inner frames 12a formed at a constant pitch. 12b, inner frame 12a
Are formed around a pair of dam bars 12c, a mounting stage 12d of the semiconductor element, a stage support bar 12e supporting the mounting stage 12d on both sides, inner leads 12f, outer leads 12g which are examples of connection terminals, and a mounting stage 12d. And a connecting piece 12h that connects the distal ends of the inner leads 12f. Continuum 12
Are formed by punching a strip-shaped metal sheet, and internal residual stress and residual strain are generated during punching.

Returning to FIG. 1, the front and back side chain conveyors 16 and 17 each include an upper feed chain 18a and a lower feed chain 19a of the front and back endless chains 18 and 19, respectively. a on the chain drive side of the downward return chain 18b and the upward return chain 19b, respectively, a cleaning device 20 for cleaning the front and rear pressing plates 14, 15, a table after cleaning, Drying devices 21 for drying the back-side pressing plates 14 and 15 are sequentially provided. Cleaning device 20
A number of nozzles 20a are provided above and below for cleaning the front and back surfaces of the back pressure plates 14 and 15 that are soiled during annealing by blowing out pressurized water. The mounting jigs 18c, 19c and the mounting plate 14 are attached to the front and rear endless chains 18, 19 at a constant pitch, respectively.
A large number of front and rear pressing plates 14 and 15 are laid horizontally via a and 15a (see FIGS. 3 and 4).

On the front and back sides of the continuous body transfer path a,
Several pairs of both ends are arranged outside the annealing furnace 11 and are urged in the direction of approach to each other. The pressing plates 14 and 15 are arranged side by side at a pitch of 2/3 of the length in the transport direction (see also FIG. 3). As described above, since the length between the front and rear-side pressing rollers 22 and 23 is set to approximately two-thirds of the length of the front and rear-side pressing plates 14 and 15 in the transport direction, each of the front and rear-side pressing rollers 22 and 23 is pressed. Plates 14, 15 are always
It is pressed by the front and rear two front and rear side pressing rollers 22 and 23. As a result, each of the front and rear pressing plates 14 and 15 being transported moves smoothly with little vertical movement when the end in the traveling direction is sandwiched between the next table and the rear pressing rollers 22 and 23. it can.

When the drive rollers 16a and 17a of the front and back chain conveyors 16 and 17 are rotated by a drive motor (not shown), the front and back endless chains 18 and 19 orbit in the direction of the arrow, whereby each table and Back pressing plate 1
4 and 15 are transferred on the front and back sides of the continuum transfer path a as the continuum 12 is transferred. At this time, when each table and the back-side pressing plates 14 and 15 are being transported, the respective tables and the back-side pressing plates 14 and 15 are synchronized with each other when reaching between the paired front and back-side pressing rollers 22 and 23. On the front and back surfaces of each electronic component lead frame 13 of the continuum 12 being transferred,
Press individually.

As shown in FIGS. 3 and 4, the extended front ends of the rotating shafts 22a and 23a at both ends of the front and back side pressing rollers 22 and 23 respectively have guide rails 24 extending upward and downward. A take-up unit 26 with a built-in bearing, which can move up and down along, is fitted inside. The respective take-up units 26 are urged in directions approaching each other by a spring 27 which is an example of an elastic member housed in the upper and lower portions of the guide rail 24. Therefore,
The front and back side pressing rollers 22 and 23 are opposed to each other in the axial direction of the front and back side pressing rollers 22 and 23 by the take-up unit 26 being moved up and down against the urging force of the spring 27. It moves up and down within the range of a pair of long holes 24a formed on the opposing side surfaces of 24. FIG.
, Reference numeral 28 denotes a front surface, the back side chain conveyor 1
In FIG. 4, reference numeral 29 denotes a front side, spacers between the rear endless chains 18 and 19, and reference numeral 30 denotes mounting jigs 18c and 19c. These pins are fixed to the ends of the mounting plates 14a, 15a of the front and back pressing plates 14, 15.

Next, a description will be given of a method of heat treating a continuous lead frame for electronic components according to an embodiment of the present invention using the heat treatment apparatus 10 for a continuous lead frame for electronic components. As shown in FIG. 1, the driving rollers 16a, 17a
When the front and back endless chains 18 and 19 circulate, the front and back endless chains 18 and 19 are arranged at a predetermined pitch on the front and back endless chains 18 and 19, respectively. The pressing plates 14 and 15 also circulate on the continuous body transfer path a in synchronization with the continuous body 12 being transferred.
As a result, the continuum 1 is located outside the vicinity of the entrance of the annealing furnace 11.
2 on the front and back surfaces of each electronic component lead frame 13,
The corresponding front and back pressing plates 14 and 15 are arranged so as to be sandwiched from above and below, respectively.
Since it is inserted between 23, it is sandwiched. Thereafter, this sandwich state is maintained by successively moving between the front and rear-side pressing rollers 22 and 23 sequentially, and the continuum 12 is passed through the continuum transfer path a in the annealing furnace 11. Annealed.

As described above, the lead frame 13 for each electronic component is sandwiched between the upper and lower surfaces by the front and back pressing plates 14 and 15 and is annealed while being kept in an appropriate shape. Retained internal residual stress and / or
Further, residual distortion is removed. That is, the internal residual stress and / or residual strain retained in the continuum 12 is eliminated by heating, and the internal residual stress and / or distortion disappears after passing through the cooling part on the outlet side of the annealing furnace 11. Since the continuum 12 is cooled in a proper shape (planar shape) gradually, even if the connecting piece 12h is cut in a later step after annealing, deformation or the like occurs at the tip of the extremely fine inner lead 12f. hard.

Each of the front and back pressing plates 14 and 15
Front and back side chain conveyor 16,
17, the cost of equipment can be reduced on the front and back sides of both sides of the continuous body transfer path a. The annealing furnace 11
After passing through the exit of the table, the nipping and conveying of the continuum 12 is completed,
The back pressing plates 14 and 15 are sequentially washed with water by the cleaning device 20 on the drive side of the return chains 18b and 19b of the front and back endless chains 18 and 19, and then dried by the drying device 21. Thereby, the front and back surfaces of the electronic component lead frame 13 sandwiched next by the used front and back surface pressing plates 14 and 15 are not stained,
Can be reused in a beautiful state.

Although the present invention has been described above, the present invention is not limited to these embodiments, and any changes in design or the like without departing from the scope of the present invention are included in the present invention. For example, in the embodiment, a lead frame for a semiconductor device is adopted as a lead frame for an electronic component. However, the present invention is not limited to this. For example, a lead frame for a relay terminal may be used. Further, in the embodiment, the punching method is adopted as a method for continuously forming the lead frame for the electronic component on the strip-shaped metal sheet for the continuum. However, the present invention is not limited to this. You may.

Further, as shown in FIGS.
The upper and lower guide rails 40, 41 are arranged on both sides of each of the upper and lower guide rails 40, 41 parallel to the continuous body transfer path a and supported by springs 40a, 41a as another example of the elastic support member. Both ends of the mounting plates 14a and 15a of the front and back pressing plates 14 and 15 are extended to the sides of the annealing furnace 11, and the respective extended portions are separated from the continuous body transfer path a on the surfaces thereof. If the running roller 43 which rolls in contact with the lower guide rails 40, 41 is arranged via the bracket 42, the upper and lower guide rails 40, 4 are provided.
1, the running roller 43 of each mounting plate 14a, 15a is rolled, so that
4 and 15 are transported smoothly in the annealing furnace 11 without moving up and down, whereby the lead frame 13 for each electronic component of the continuum 12 of the pair of front and rear pressing plates 14 and 15 is firmly fixed. The sandwiching state is set such that the front and back pressing plates 14 and 15 are connected to the continuous body transfer path a of the annealing furnace 11.
Can be maintained at all times during transport.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of a heat treatment apparatus for a continuous lead frame for electronic components to which a heat treatment method for a continuous lead frame for electronic components according to an embodiment of the present invention is applied.

FIG. 2 is an enlarged plan view of a main part of a continuum.

FIG. 3 is an enlarged side view of a main part of a pressing roller.

FIG. 4 is an enlarged front view of a main part of a pressing roller.

FIG. 5 is an enlarged schematic cross-sectional view of a main part of a heat treatment apparatus for a continuous lead frame for electronic components used in a method for heat treating a continuous lead frame for electronic components according to another embodiment of the present invention.

FIG. 6 is an enlarged schematic side view of the main part.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 Heat treatment apparatus of lead frame continuous body for electronic parts 11 Annealing furnace 12 Continuous body 12a Inner frame 12b Side rail 12c Dam bar 12d Mounting stage 12e Stage support bar 12f Inner lead 12g Outer lead 12h Connection piece 13 Electronic component lead frame 14 Surface pressing Plate 14a Mounting plate 15 Back side pressing plate 15a Mounting plate 16 Front side chain conveyor 16a Drive roller 17 Back side chain conveyor 17a Drive roller 18 Front side endless chain 18a Feed chain 18b Return chain 18c Mounting jig 19 Back side endless chain 19a Feed chain 19b Return chain 19c Mounting jig 20 Cleaning device 20a Nozzle 21 Drying device 22 Front side pressing roller 22a Rotary shaft 23 Back side pressing Roller 23a Rotary shaft 24 Guide rail 24a Slot 26 Take-up unit 27 Spring 28 Guide roller 29 Spacer 30 Pin 40 Upper guide rail 40a Spring 41 Lower guide rail 41a Spring 42 Bracket 43 Traveling roller a Continuous body transfer path

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-114249 (JP, A) JP-A-8-213528 (JP, A) JP-A-9-64268 (JP, A) JP-A-4- 22157 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 23/50 C21D 1/00 113 C21D 9/00

Claims (5)

(57) [Claims] 1. An internal residual stress and / or residual strain retained in a continuum of a single lead frame for an electronic component having a plurality of connection terminals whose tips are connected by connecting pieces, the continuum being annealed. What is claimed is: 1. A method for heat-treating a continuous lead frame for electronic components, wherein the lead frame is continuously removed by heating while passing through a furnace. By a pressing plate, the front surface of each single electronic component lead frame, in a state where the back surface is individually pressed, the continuous body and the table arranged in each pair,
The lead frame for electronic parts, wherein the internal residual stress and / or residual strain of the lead frame for electronic parts is continuously removed by synchronously moving the back surface pressing plate along the continuous body transfer path. Heat treatment method for continuum. 2. Each of the surface pressing plates is laid at a predetermined pitch between a pair of surface-side endless chains arranged on the surface side of both sides of the continuous body transfer path via a mounting plate. Further, each of the back-side pressing plates is interposed at a predetermined pitch between a pair of back-side endless chains disposed on the back side of both sides of the continuous body transfer path via the mounting plate, respectively, By rotating the front and back endless chains synchronously, the paired front and rear pressing plates respectively press the electronic component lead frames of the continuum sequentially and individually, 2. The method according to claim 1, wherein the lead frame is transferred along a transfer path. 3. A plurality of pairs of movable front and rear side pressing rollers, which are arranged side by side on the front and rear sides of the continuous body transfer path at a pitch shorter than the length of the front and rear pressing plates in the transport direction. Are urged in a direction approaching each other through a plurality of elastic members, so that each table being transferred along the continuum transfer path, the back-side pressing plate is a table in which each pair is arranged, the back side. When reaching between the pressing rollers, each of the front and back pressing plates is sequentially and individually pressed against the front and back of each electronic component lead frame of the continuous body during the synchronous transfer. Item 3. The heat treatment method for a continuous lead frame for an electronic component according to Item 1 or 2. 4. An upper and lower guide rail, which is parallel to the continuous body transfer path and is supported by an elastic support member, is disposed on both sides of the annealing furnace, and the front and back surface pressing plates are attached. Both ends of the plate are extended to the side of the annealing furnace, and the respective rolling portions are in contact with the upper and lower guide rails on the surfaces of the extended portions that are separated from the continuous body transfer path, and roll. 3. The method for heat treating a continuous lead frame for an electronic component according to claim 1, wherein a roller is provided. 5. A cleaning device for the front and back pressing plates is provided on a portion of the front and back side endless chain outside the annealing furnace, and the front and back pressing plates passing through the annealing furnace are provided.
The heat treatment method for a continuous lead frame for an electronic component according to claim 2, wherein the lead frame is sequentially washed.