JPH09129661A - Molding device and molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent roughened surfaces from being formed on the clamping surfaces of a top force with a bottom force. SOLUTION: Clamping surfaces 40a and 40b are formed on the joining surfaces of a top force 31 with a bottom force 32 along the outside periphery of a cavity 33 and escape recessed places 41a and 41b are formed in the region coming into contact with the intersecting part of a dam bar 10 on the clamping surfaces with an inner lead 9 into a low step shape along the inside end side parts of the clamping surfaces in such a way that the clamping surfaces do not come into contact with the lead 9 at the time of a molding work. At the time of the molding work, the clamping surfaces 40 pinch a lead frame on the outside of the cavity 30, but as the regions, where are formed with the escape recessed places 41, of the clamping surfaces 40 pinch the dam bar part only without coming into contact with the inner lead 9, roughened surfaces due to the contact of the regions with the inner lead 9 are not formed on the surfaces 40. As the roughened surfaces are not formed, a lead frame of a standard, wherein the form and pitch of inner leads are different from those of the inner leads 9, can be used in the same molding die.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for molding a resin molded product, and more particularly to a resin molding technique using a molding die, for example, molding a resin encapsulant in a semiconductor device equipped with a resin encapsulation package. The present invention relates to a molding technique effectively used for

[0002]

2. Description of the Related Art Generally, a semiconductor integrated circuit device provided with a resin-sealed package (hereinafter referred to as resin-sealed package IC
That. ) Is manufactured by using a lead frame provided with a dam bar (also called a tie bar) that is integrally installed between adjacent outer leads to dam the resin, and the lead frame is transferred by a transfer molding device. The resin sealing body is molded. That is, a general transfer molding apparatus includes a molding die including an upper die and a lower die that are fitted to each other, and a cavity for molding a resin sealing body is provided on a mating surface of the upper die and the lower die. It is buried. Further, on either mating surface of the upper mold or the lower mold, a gate communicated with the pot via a runner is provided in the cavity with a liquid resin (hereinafter, referred to as a molding material).
Called resin. ) Is submerged so that it can be injected.
Then, after the lead frame is arranged and sandwiched between the mating surfaces of the upper mold and the lower mold so that the dam bar group surrounds the outer periphery of the cavity, the resin is filled into the cavity through the runner and the gate. A resin sealing body is molded.

Incidentally, as an example in which the resin encapsulation body molding process of the resin encapsulation package IC is described, Nikkei BP 199
There is "Practical course VLSI packaging technology (below)" P31-P40 issued on May 31, 3rd.

[0004]

When the resin molding is molded on the lead frame by such a transfer molding device, the inner end side of the dam bar in the lead frame is located slightly outside the outer periphery of the cavity. Since the inner lead is located inside the dam bar, the root of the inner lead is located outside the cavity. For this reason, the mold is clamped with the root portion of the inner lead being sandwiched between the clamp surfaces of the upper mold and the lower mold. As a result, when a lead frame having an inner lead group with the same shape and the same pitch is clamped between the clamping surfaces of the upper die and the lower die, and the molding operation is repeatedly performed, the root portion of the inner lead on the clamping surface is Since the contacting portion undergoes plastic deformation, uneven portions are alternately formed on the tightening surface along the inner lead alignment direction.

In this way, the upper die and the lower die having the concavo-convex portion formed instead of the flat clamping surface as a whole are shared, and the lead of another standard having the inner lead group having different lead width and pitch standards is used. When the work of molding the resin sealing body on the frame is performed, the inner lead is formed on the tightening surface when the lead frame is sandwiched between the mating surfaces of the upper die and the lower die and the die is clamped. There is a possibility that the uneven portion may be deformed by being displaced toward the concave portion side, and when the deformation amount is large, a defect occurs in which adjacent inner leads come into contact with each other.

An object of the present invention is to provide a molding technique capable of preventing the uneven surface from being formed on the tightening surface.

[0007] The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

[0008]

The outline of a typical invention among the inventions disclosed in the present application is as follows.

That is, a cavity is formed in cooperation with the mating surfaces of the upper mold and the lower mold that are clamped to each other, and a clamping surface surrounding the cavity is formed on the mating surface. In the above, the relief recess is formed in a low step shape in the cavity side region of the tightening surface.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a method for molding a SOP / IC resin encapsulant, which is an embodiment of the present invention.
(A) is an enlarged partial sectional view cut along the dam bar portion, and (b) is an enlarged partial sectional view cut along the inner lead portion. 2 is a partially omitted plan view showing a lead frame as the work, FIG. 3 shows an assembly as the work, (a) is a partially omitted plan view, and (b) is a part (b) of (a). It is a front sectional view taken along the line -b. FIG. 4 and FIG. 5 are each a structural diagram showing a main part of a transfer molding apparatus which is an embodiment of the present invention.

In this embodiment, the transfer molding method according to the present invention comprises a small outline package, which is an example of a resin-sealed package IC.
It is used to mold C (hereinafter referred to as SOP / IC) packages. The work supplied to this transfer molding method is manufactured by the multiple lead frame 1 shown in FIG. This multiple lead frame 1 is made of a thin plate made of a copper-based (copper or its alloy) material or an iron-based (iron or its alloy), and is integrally formed by punching and pressing. A plurality of unit lead frames 2 are arranged side by side in a row in the multiple lead frame 1. However, illustration and description will be made for one unit.

The unit lead frame 2 has a pair of outer frames 3 each having a positioning hole 3a.
Are arranged so as to be parallel to each other at a predetermined interval and extend in series. Adjacent unit lead frames 2, 2
A pair of section frames 4 are disposed between the outer frames 3 and 3 in parallel with each other and integrally erected. A substantially rectangular shape formed by these outer frames 3 and 3 and section frames 4 and 4. The unit lead frame 2 is formed in the frame body (frame) 5.

A pair of tab suspension leads 6, 6 are respectively provided at the central portions of the outer frames 3 and 3 and are integrally projected. The tab suspension leads 6 each have a substantially rectangular flat plate shape at the tip thereof. The tab 7 formed in the above is arranged substantially concentrically with the frame shape of the frame body 5 and is integrally suspended. Both section frames 4,
A plurality of outer leads 8 are arranged on the inner edge of the section frame 4 at equal intervals in the direction along the edge and are parallel to each other.
And an inner lead 9 is integrally formed at the tip of each outer lead 8.
The tip of each inner lead 9 is arranged close to the tab 7 and surrounds it. Incidentally, in the present embodiment, the tab 7 is lowered in the back surface direction by the thickness of the semiconductor pellet (hereinafter referred to as pellet) from the surface of the inner lead 9 group (so-called tab lowering). In addition, a dam bar 10 is installed between the outer leads 8 and 8 at a portion adjacent to the inner lead 9 so as to stop the flow of resin between the outer leads 8 and 8 which are adjacent to each other at the time of molding a resin encapsulating body which will be described later. There is.

On the multiple lead frame 1 constructed and prepared as described above, pellet bonding work and then wire bonding work are carried out for each unit lead frame 2, and by these works, as shown in FIG. The assembly 20 shown in FIG. The assembly 20 is supplied as a work to the transfer molding apparatus.
First, a pellet 22 as a semiconductor integrated circuit structure in which an integrated circuit (not shown) including a semiconductor element is formed in a previous step by a pellet bonding operation is formed in a substantially central portion on the tab 7 in each unit lead frame 2. And is fixed via a bonding layer 21 formed of a suitable material such as silver paste. The silver paste is formed by mixing an epoxy resin adhesive, a curing accelerator, and a solvent with silver powder, and after the pellets are pressed against the silver paste applied onto the lead frame, the silver paste is appropriately applied. The bonding layer 21 is formed by being cured (cured) by temperature.

Between the bonding pad 22a of the pellet 22 fixedly bonded to the tab 7 and each inner lead 9 in the unit lead frame 2,
The wire 23 formed by using a copper-based material (copper or copper alloy) is bonded at both ends thereof by using an appropriate wire bonding device such as an ultrasonic thermocompression bonding type. Entangled. By the above bonding work, the integrated circuit built in the pellet 22 has bonding pads 22a, wires 23,
It will be electrically drawn out through the inner lead 9 and the outer lead 8.

Assembled product 2 after being pellet-bonded and wire-bonded to the multiple lead frame as described above.
0 is supplied to the transfer molding device as a work,
A group of resin encapsulants for resin encapsulation for each unit lead frame is simultaneously molded for the unit lead frame group using a transfer molding device.

The transfer molding apparatus 3 according to this embodiment
Reference numeral 0 is provided with a pair of upper mold 31 and lower mold 32 that are clamped together by a cylinder device (not shown).
A plurality of rectangular upper flat mold cavity recesses 33a and lower mold cavity recesses 33b are formed on the mating surfaces of the lower mold 32 and the lower mold 32 so as to cooperate with each other to form the cavity 33. It is buried. A pot 34 is opened on the mating surface of the upper mold 31, and a tablet (not shown) made of resin as a molding material is placed in the pot 34 and a plunger 35 is advanced and retracted by a cylinder device (not shown). The liquid resin (resin) obtained by melting this tablet can be fed. On the mating surface of the lower die 32, culls 36 are arranged in a position facing the pot 34 and are buried therein, and a plurality of runners 37 are arranged in a radial pattern so as to be connected to the pot 34, respectively. ing. The other end of each runner 37 is connected to the lower cavity recess 33b, and a gate 38 is formed at the connection so that the resin can be injected into the cavity 33.

Recesses 39a and 39b are respectively recessed in the mating surfaces of the upper mold 31 and the lower mold 32, and the upper mold 31 and the lower mold 32 are formed by the recesses 39a and 39b.
Tightening surfaces 40a and 40b are relatively formed on the mating surface along the outer periphery of the cavity 33. Both tightening surfaces 4 formed along the outer periphery of the cavity 33
0a, 40b, in the region facing the dam bar 10 and the inner lead 9 of the unit lead frame 2, the relief recesses 41a, 41b have fastening surfaces 40a, 40b at the base of the inner lead 9 with the dam bar 10 during the molding operation described later. Each of the tightening surfaces 40a and 40b is formed in an extremely shallow stepped shape having a constant width and a constant depth along the inner side edges thereof so as not to contact the portions. During a molding operation described later, both fastening surfaces 40a and 40b formed on the mating surfaces of the upper die 31 and the lower die 32 sandwich the portion of the unit lead frame 2 that faces the outer periphery of the cavity 33. At this time, since the tightening surfaces 40a and 40b in the regions facing the outer leads 8 and the inner leads 9 have the recessed recesses 41a and 41b respectively sunk in the cavity side regions, only the portion of the dam bar 10 is sandwiched. It will be.

Next, a transfer molding method using the transfer molding apparatus 30 having the above structure will be described.

At the time of transfer molding, the assembly 20 after pellet wire bonding as a work is put in the lower die 32 and the pellet 22 in each unit lead frame 2 is formed.
Are arranged and set so as to be housed in the respective cavities 33. In this state, as shown in FIGS. 1, 4 and 5, the unit lead frame 2
The inner side edge 10a of the dam bar 10 at is slightly separated from the lower mold cavity recess 33b, that is, the outer periphery of the cavity 33 by a certain size. That is, the correlation between the dam bar 10 and the cavity 33 is such that the inner end side 10a of the dam bar 10 and the outer periphery of the cavity 33 face each other with a narrow predetermined dimension when molding the resin sealing body. It is set.

Next, the upper die 31 and the lower die 32 are clamped. By this mold clamping, the upper and lower mold clamping surfaces 40a, 40
In the case of b, the unit lead frame 2 is tightened in the narrow region outside the outer peripheral edge of the cavity 33. At this time, in the portion of the inner lead 9 located between the outer periphery of the cavity 33 and the inner end side of the dam bar 10, the escape recesses 41a and 41b are recessed in the fastening surfaces 40a and 40b. Only the portion of the dam bar 10 is not pressed by the tightening surfaces 40a and 40b, and only the part of the dam bar 10 is tightened.
It is in a state of being sandwiched by a and 40b.

In this way, the tightening surfaces 40a, 40b come into contact with the flat dam bar 10, so that the tightening surfaces 40a, 40b are
Since b is not plastically deformed in an uneven shape by the pressed surface, the tightening surfaces 40a and 40b can always maintain a flat surface. Therefore, even when the same molding die is used to mold the resin encapsulant on lead frames of different standards having different lead widths and lead pitches, the upper mold 31 and the lower mold 32 are formed.
It is possible to prevent the inner leads from being deformed at the time of mold clamping, and it is possible to prevent a problem that the inner lead portions adjacent to each other come into contact with each other.

By the way, as shown in FIGS. 9 (a) and 9 (b), in the case of the conventional example in which the relief recess is not formed in the tightening surface, the leads having the same lead width and the same lead pitch are used. When the resin molding work is repeatedly performed on the frame, as shown in FIGS. 9B and 9C, the dam bar 10 and the inner lead 9 intersect with each other on the fastening surfaces 50a and 50b having no escape recess. The portion that repeatedly contacts the portion (the root portion of the inner lead) is crushed or worn to be plastically deformed to be recessed, and the inner leads 9 are aligned on the tightening surfaces 50a and 50b having no escape recess. An uneven surface is formed along the direction corresponding to the lead width W and the lead pitch P.

By using the upper die and the lower die having the tightening surfaces 50a and 50b having the uneven surface as described above, a lead frame of different standards having different lead widths and lead pitches is formed. Is carried out, FIG. 9 (d)
As shown in FIG. 5, when the lead frame is clamped between the mating surfaces of the upper die 31 and the lower die 32, the uneven width and the uneven pitch of the uneven surface, the lead width W ′ of the inner lead 9 ′, and the lead Due to the deviation from the pitch P ',
Since the inner leads 9 ′ that come into contact with the uneven surface portion are pushed from the convex portion to the concave portion, the inner leads 9 ′ are displaced and deformed, and as shown in FIG. In some cases, a defect in which they contact each other may occur. However, as described above, in the molding apparatus according to the present embodiment, the relief recesses 41a and 41b prevent the occurrence of uneven surfaces on the tightening surfaces 40a and 40b.
The occurrence of such defects can be avoided in advance.

After the upper mold 31 and the lower mold 32 are clamped as described above, the resin 42 as a molding material is fed from the pot 34 to the cavities 33 through the runner 37 and the gate 38 by the plunger 35. It is pressed in respectively. The resin 42 press-fitted into the cavity 33 leaks to the outside of the cavity 33 from between the outer leads 8 which are adjacent to each other between the mating surfaces of the upper mold 31 and the lower mold 32 as the resin 42 is filled. However, the cavity 33 has a dam bar 1 between the outer leads 8 which are adjacent to each other.
Since it is surrounded by the group 0, the resin 42 leaking from the cavity 33 does not flow beyond the dam bar 10 to the outside. Inside edge 10a of the dam bar 10
Since the size of each part is set so that the gap between the cavity 33 and the outer peripheral edge of the cavity 33 is extremely small, even if a space burr is formed, the protrusion amount thereof is extremely small and does not hinder the operation. Become. The space burr can be deburred by a punching die device, a shot blasting device, or the like.

Further, the resin 42 press-fitted into the cavity 33 is filled with the resin, and the fastening surfaces 40a, 4a of the upper die 31 and the lower die 32 on the outer peripheral edge of the cavity 33 are formed.
At the escape recesses 41a and 41b at 0b, the surface leaks to the surfaces of the dam bar group 10 and the lead portion inside thereof, forming a surface burr. However, this surface burr is extremely thin, and since the mold release agent is mixed in the resin 42, it can be easily deburred by jetting high-pressure water or the like.

After the injection, when the resin is thermoset and the resin encapsulant 24 is molded, the upper mold 31 and the lower mold 32 are opened, and the resin encapsulant is ejected by an ejector pin (not shown). Twenty-four groups are released. That is, the resin molding 24 is molded on each unit lead frame 2 of the multiple lead frame 1, and the assembly 25 after molding the resin molding shown in FIGS. 6 and 7 is the transfer molding device 30.
Dismantled from. The pellet 22, the inner lead 9 and the wire 23 are resin-sealed inside the resin-sealed body 24 resin-molded in this way.

Then, the assembly 25 after molding the resin encapsulant is sent to a lead cutting molding step (not shown), and unnecessary portions such as the dam bar 10 are cut off by the lead cutting device, and the lead molding is performed. Each outer lead 8 is bent and formed into a gull wing shape by the device. With the above manufacturing method, the SOP IC 26 shown in FIG. 8 is manufactured.

According to the above embodiment, the following effects can be obtained. (1) By forming an escape recess on the tightening surface of the mating surface of the upper mold and the lower mold and tightening the dam bar portion of the lead frame by the tightening surface, the dam bar and the inner lead on the tightening surface Since it is possible to prevent plastic deformation due to repeated tightening of the portion contacting the intersecting portion of, it is possible to avoid forming an uneven surface on the tightening surface.

(2) According to the above (1), even when lead frames of different standards having different lead widths and lead pitches are molded using the same molding die, the inner leads are pressed and deformed by the uneven surface. Therefore, it is possible to prevent the problem that the inner leads adjacent to each other come into contact with each other.

(3) Since the same molding die is shared by lead frames of a plurality of standards, the cost of the molding die can be saved, so that the manufacturing cost as a whole of semiconductor device production can be reduced.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention is not limited to the above embodiment, and various modifications can be made without departing from the gist of the invention. Needless to say.

For example, when the tightening margin of the tightening surface is reduced by the amount of the recessed recess being recessed, and there is a possibility of malfunction, the width of the dam bar of the lead frame is set to be large and the tightening surface is It is also possible to supplement the tightening allowance by escaping the tightening allowance and increasing the outside by the amount of the recess recessed.

Further, in the above description, the invention made by the present inventor was mainly described as a technique for forming a resin encapsulating body for SOP / IC, which is a field of use which is the background of the invention.
The present invention is not limited to this, and can also be applied to a resin encapsulant molding technique such as an IC (QFP IC) having a quad flat package in which outer leads are projected in four directions.

[0035]

The effects obtained by typical aspects of the invention disclosed in the present application will be briefly described as follows.

By forming relief recesses in the tightening surfaces formed along the outer periphery of the cavity on the mating surfaces of the upper mold and the lower mold, the dam bar is molded during the molding work for molding the resin sealing body on the lead frame. Since it is possible to avoid the crossing portion between the inner lead and the inner lead from pressing against the tightening surface, it is possible to prevent the uneven surface from being formed on the tightening surface due to plastic deformation accompanying repeated use of the molding die. .

For example, when a plurality of standard lead frames having different lead shapes and pitches are used to form a resin encapsulant using the same molding die, it is possible to prevent uneven surfaces from being formed on the tightening surface. Therefore, it is possible to prevent the inner leads from being deformed during the molding operation after the standard exchange, and it is possible to prevent the occurrence of the problem that the inner leads adjacent to each other come into contact with each other. By sharing the same molding die for lead frames of a plurality of standards, it is possible to reduce the manufacturing cost of the entire semiconductor device production.

[Brief description of the drawings]

FIG. 1 shows a method for molding a resin sealing body of an SOP / IC, which is an embodiment of the present invention, in which (a) is an enlarged partial sectional view taken along a dam bar portion and (b) is an inner lead. It is an expanded partial sectional view cut along a part.

FIG. 2 is a partially omitted plan view of a lead frame.

3A and 3B show an assembled product after pellets and wire bonding, wherein FIG. 3A is a partially omitted plan view, and FIG. 3B is a front sectional view taken along line bb of FIG.

FIG. 4 shows a main part of a transfer molding apparatus according to an embodiment of the present invention, in which (a) is a side sectional view and (b) is a sectional view.
Is a front sectional view.

FIG. 5 is a partially omitted enlarged plan view of the lower mold.

FIG. 6 is a partially cutaway partially cutaway plan view showing the assembly after molding the resin encapsulant.

FIG. 7A is an enlarged partial cross-sectional view similarly cut along the dam bar portion, and FIG. 7B is an enlarged partial cross-sectional view cut along the inner lead portion.

FIG. 8 is a perspective view showing an SOP / IC.

9A and 9B are explanatory views of a conventional example, FIG. 9A is an enlarged partial cross-sectional view showing a molding process of a resin sealing body, FIG. 9B is a partial plan view showing a relationship between a tightening surface and a lead frame, (c) is a vertical cross-sectional view showing the inner lead sandwiched between the fastening surfaces, (d) is a vertical cross-sectional view showing a state in which lead frames of different standards are sandwiched, and (e) is a partial plan view showing the deformed lead frame. It is a figure.

[Explanation of symbols]

1 ... multiple lead frame, 2 ... unit lead frame, 3
... outer frame, 4 ... section frame, 5 ... frame body (frame), 6
... Tab suspension lead, 7 ... Tab, 8 ... Outer lead, 9 ...
Inner lead, 10 ... Dam bar, 10a ... Inner edge, 2
0 ... Pellet wire assembly (work) after wire bonding, 21 ... Bonding layer, 22 ... Pellet, 23 ...
Bonding wire, 24 ... Resin encapsulant, 25 ... Assembly after resin encapsulant molding, 26 ... SOP / IC (semiconductor device), 30 ... Transfer molding device, 31 ... Upper mold, 32
... lower mold, 33 ... cavity, 33a ... upper mold cavity recess, 33b ... lower mold cavity recess, 34 ... pot, 35 ... plunger, 36 ... cul, 37 ... runner, 3
8 ... Gate, 39a, 39b ... Recess, 40a, 40b ...
Clamping surface, 41a, 41b ... Escape recess, 42 ... Resin, 5
0a, 50b ... Tightening surface with no recess.

Claims (3)

[Claims] 1. A molding apparatus in which a cavity is formed in cooperation with a mating surface of an upper die and a lower die which are clamped to each other, and a clamping surface surrounding the cavity is formed on the mating surface. 2. The molding apparatus according to claim 1, wherein a relief recess is formed in a low step shape in the cavity side region of the tightening surface. 2. Using the molding apparatus according to claim 1,
A molding method for resin-molding a resin sealing body on a lead frame having a dam bar intersecting an outer lead and an inner lead, wherein the tightening surface tightens a region on the outer lead side of the dam bar, and the escape recess A molding method, characterized in that the resin encapsulant is molded by the cavity in a state where the cross section of the dam bar and the inner lead escapes. 3. The molding method according to claim 2, wherein the shortage of the tightening margin due to the relief recess on the tightening surface is compensated by increasing the width of the dam bar.