JPH02111039A - Method for manufacturing semiconductor devices and resin molding equipment used therein - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of manufacturing a semiconductor device, and particularly to a technique that is effective when applied to a resin molding process in manufacturing a resin-sealed semiconductor device.

[Conventional technology]

An example of this type of technology described is Japanese Patent Laid-Open No. 52-95765.

The above-mentioned publication describes in detail the resin molding device used to form a package in the manufacturing process of a resin-sealed semiconductor device, and particularly the mold structure thereof.

Generally, in such a resin molding device, a plurality of cavities are formed in each facing portion of a pair of molds consisting of an upper mold and a lower mold, and a lead frame is placed between both molds. The package is formed by injecting molten resin into the cavity at high pressure and heating and hardening the resin in the shape of the cavity around the lead frame.

The outline of such a resin molding device will be explained in more detail using FIG. 11.

In the figure, a lower mold 54 is fixed on a lower mold base unit 53 (substrate) supported by a support pillar 52 vertically installed above a lower movable platen 51.

The lower mold 54 is heated to a predetermined temperature by a heater 55 as a heat source built into the lower mold base unit 53.

An upper mold 57 fixed to the lower surface of the upper mold base unit 56 is installed above the lower mold 54, and both molds 5
Cavities 58 are formed in the molding dividing planes (parting planes P) corresponding to the respective parts 4.57. Inside the upper mold base unit 56, there is a heater 55 as described above.
The upper mold 57 is heated by heating the upper mold 57.

Further, this upper mold base unit 56 is connected to the support pillar 5.
2, it has a structure fixed to the upper fixed platen side (not shown).

A cylindrical pot 60 is disposed approximately vertically in the center of the upper die base unit 56 and the upper die 57, and a plunger 61 is disposed inside the pot 60 so as to be slidable in the sleeve direction. There is.

In the above configuration, the IJ-de frame 62, which is the object to be molded, is composed of an upper mold 57 and a lower mold 54).
It is disposed within a cavity 58 that is In this state, the tablet 63 (package resin material) housed in the pot 60 is melted by heating by the heater 55 and transfer pressure by the plunger 61, and is injected into the cavity 58 under high pressure through the runner 64 and the gate 65. A package corresponding to the cavity shape is formed.

In the resin molding process, the upper mold 57 and the lower mold 5
If an equal mold clamping force is not applied to all the inserts such as the lead frame 62 held by the parting surface P between the parting surface P and This gap causes the resin to ooze out, a so-called resin flash R. FIG. 12 shows the state of occurrence of such resin fludge, H.

[Problem to be solved by the invention]

A product in which the resin flash R has occurred to such an extent that it covers the surface of the lead 66 not only has an unfavorable appearance but also results in a decrease in soldering performance and sealing reliability. Further, there are other disadvantages, such as the work to remove the resin flash R generated in this way is complicated.

On the parting surface P, the causes of the above-mentioned gap include the machining accuracy of the lead frame 62, and
The assembly and processing accuracy of the upper mold 57 and the lower mold 54, and the heater 5 built into each base unit 5356.
This gap is mainly caused by the flatness error caused by the difference in thermal expansion between the heated portion and the non-heated portion by 5, the transfer pressure of the plunger 61, the platen pressurization, etc., and the synergistic effect of these causes the above-mentioned gap. In FIG. 1I, the two-dot chain line indicates the distorted shape of the lower die base unit 53 due to the transfer pressure of the plunger 61, and the broken line indicates the deformed shape of the movable platen 51 due to the platen pressurization. It shows.

In order to prevent such deformation, the height of the corresponding part of the support pillars 52, which are arbitrarily arranged in the initial design of the device, is adjusted by cutting or inserting a spacer. However, adjusting the height of the support pillar 52 requires highly accurate technology, and furthermore, the deformed shape changes over time, so it has been difficult to completely adjust the height. Therefore, a sufficient effect in preventing the occurrence of resin fluff 5R has not been achieved.

The present invention has been made with attention to the above-mentioned problems, and its purpose is to provide a technology that can prevent the occurrence of resin flash during resin molding and realize highly reliable pancage molding. .

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

[Means to solve the problem]

A brief overview of typical inventions disclosed in this application is as follows.

That is, in the resin molding process, high-pressure injection of resin into the cavity is performed while the stress locally applied to the molding dividing plane of the mold is evenly distributed over the entire molding dividing plane.

In addition, in order to realize the above-mentioned stress distribution, the mold or the base holding the mold is equipped with a pressure equalization mechanism consisting of a plurality of cylinders filled with fluid and connected to each other by fluid flow pipes. Each cylinder of the pressure equalization mechanism is structured to support the mold or the base body by its respective rod end surface.

[Effect]

According to the above-mentioned means, firstly, by performing high-pressure injection of resin while uniformly dispersing the stress locally applied to the molding dividing plane of the mold, the thermal expansion difference of the mold or the plunger It is possible to prevent flatness errors in the molding division plane due to deformation of the mold due to transfer pressure, platen pressurization, etc., and it is possible to effectively prevent resin flash due to the generation of gaps.

Second, by providing a pressure equalization mechanism and connecting the cylinders of this pressure equalization mechanism to each other through fluid flow pipes, the locally applied stress is evenly distributed over the entire molding division plane of the mold. can be dispersed into Therefore, it is possible to correct the flatness error of the molded parting surface without requiring highly accurate and complicated adjustment work such as cutting of support pillars or insertion of spacers, and it is possible to prevent resin flash due to the occurrence of gaps.

〔Example〕

Fig. 1 is a sectional view showing the vicinity of the mold of a resin molding device which is an embodiment of the present invention, Fig. 2 is an overall configuration diagram of this resin molding device, and Fig. 3 is a forming state on the parting surface of the lower mold. FIG. 4 is a perspective view showing the pressure equalizing mechanism in this embodiment, FIG. 5 is an explanatory diagram showing variations in the plate thickness of the lead frame, and FIGS. 6 and 7 are the plates of the lead frame. FIGS. 8 and 9 are explanatory diagrams showing the relationship between the thickness dimensional error and the occurrence of resin flash. FIGS. FIG. 2 is a cross-sectional view showing a semiconductor device.

As shown in FIG. 2, the resin molding device 1 used in this embodiment includes an upper mold part 3 held by an upper fixed platen 2 and a lower mold part 5 supported by a lower movable platen 4. have. The detailed structure of the upper mold part 3 and the lower mold part 5 is as shown in FIG. 1, and the details will be described later.

The fixed platen 2 is supported above the stage of the device base 6 by a column 7 vertically installed from the device base 6, and a transfer cylinder 10 into which the tablet 8 is inserted is attached to the top of the fixed platen 2. ing. on the other hand,
A platen driving cylinder 11 for moving the movable platen 4 up and down is provided at the bottom of the apparatus base 6, and this platen driving cylinder 11 is controlled by a control section 12 disposed on the side of the stage.

Next, the structure of the upper mold part 3 and the lower mold part 5 will be explained using FIG. 1.

In the figure, the lower mold part 5 includes a movable platen 4, a pressure equalizing block 13, a lower mold base unit 14, and a lower mold 15.
It is made up of. On the other hand, the upper mold part 3 is connected to a movable platen 4.
It is composed of an upper mold base unit (17) held by a support pillar 16 hanging down, a stopper mold 18, a pot 20, and a plunger 21.

In the figure, a lower mold base unit 14 fixing the lower mold 15
The upper mold base unit 17 that fixes the upper mold 18 has heaters 22 as heating sources built in at multiple locations, and is structured to heat the upper mold 18 and the lower mold 15. . Further, as shown in detail in FIG. 4, the lower mold base unit 14 has a configuration in which a contact slope 24 is provided at the bottom of the unit main body 14a via a cut Qli 23. The heat insulating plate 23 blocks heat from the heater 22 and prevents the temperature of the hydraulic oil 25 (described later) in the pressure equalizing block 13 from rising.

In addition to the heat insulating plate 23, a forced cooling mechanism such as water cooling (not shown) may be provided on the pressure equalizing block 13 side.

A cylindrical pot 20 is vertically installed approximately at the center of the upper mold base unit 17 and the upper mold 18.
A plunger 21 is installed inside the pot so as to be slidable in the axial direction of the pot.

A parting surface P composed of an upper mold 18 and a lower mold 15 is connected to a cull 26 corresponding to the lower end opening of the pot 20 when both molds 18 and 15 are in a closed state, and a passage for molten resin is formed. A runner 27 configured as a runner 27, a gate 28 functioning as a pressurizing means, and a cavity 3 that holds a lead frame 30 as an object to be molded.
1 are formed respectively.

Runner 27 and cavity 3 in the lower mold 15
Fig. 3 shows the wiring/arrangement state of No. 1, and this figure shows a route for supplying molten resin from a single pot 20 (cull 26) to a plurality of cavities 31 through a launch 27. Note that in the same figure, the lower mold 15 in which the runner 27, gate 28, and cavity 31 are formed is shown.
is shown as a chain unit structure that can be divided into multiple parts. In the figure, a case is shown in which there are eight chase units, but the number of chase units can be changed as necessary, such as four or six.

In addition, in the same figure, a so-called single-pot system, which is composed of a single pot 20, has been described, but a so-called multi-pot system, which has a plurality of pots 20, may also be used.

Next, the configuration of the pressure equalizing block 13, which is the pressure equalizing mechanism of this embodiment, will be explained using FIG. 1 and FIG. 4.

The pressure equalizing block 13 of this embodiment has five hydraulic cylinders 81 to 81 in the block body 13a as an outer enclosure.
S5 is arranged, and each hydraulic cylinder 81 to S5 is
They are connected to each other by a flow pipe 32 (fluid flow pipe). Therefore, the hydraulic oil 25 filled in the hydraulic cylinders is transferred to each other's hydraulic cylinders 81 through this flow pipe 32.
~85 can flow and functions as an interlocking cylinder. A floating rod 33 is arranged at the upper end of each cylinder 81 to S5, and the end surface of each rod 33 is connected to the block body 13a as shown in FIG.
It is protruding from the top surface.

Further, the rod 3 is provided on the upper surface of the block main body 13a.
A stopper 34 of a predetermined height is formed to protrude from the end face of the rod 3, and the maximum displacement of the rod 33 by the hydraulic cylinders S1 to S5 is determined by the height of the stopper 34.

Next, the set values of each part of the pressure equalizing block 13 will be explained based on the matters to be considered.

According to the research of the present inventor, the variation in the frame thickness of the lead frame 30 whose thickness is set to 0.25 mm is as shown in FIG.
It was found that the particles were concentrated in 20 μm between mm.

FIGS. 6 and 7 show the influence of such a variation in plate thickness of 20 μm on the occurrence of resin flash R.

That is, FIG. 6 shows the package body 3 after resin molding.
The generation level of resin flash R from 5 to dam 37 and lead 36 is shown in six levels from 0 to 5, and the numbers surrounded by O in the figure correspond to the ranks in FIG. Here, 0 rank means that the occurrence of resin flash R is not recognized at all, and 1 rank means that resin flash R occurs, but dam 3 of lead frame 30
Those within the range of 7, 2 ranks are Resin Flash R
3rd rank is the one that occurs on the dam 37, 3rd rank is the one that exceeds the dam 37, 4th rank is the one that is at the permissible limit in the position immediately before the lead 36, and 5th rank is that the resin flash R occurs beyond this and reaches the top of the lead 36. Each shows what is happening.

From the above points, even if the machining accuracy at the parting surface P1 between the upper mold 18 and the lower mold 15 is maintained at the initial setting state, the tolerance range may be exceeded due to a variation of 20 μm in the lead frame 30. Since a lot of resin fluff sR occurs on the surface of the door 36, the stress fraction by the pressure equalizing block 13 must also be able to absorb this range. FIG. 3 is an explanatory diagram showing the relationship between the pressure applied to the area and the position of the tip of the resin flash R.

As is clear from the figure, the occurrence of resin flash R can be suppressed by increasing the surface pressure, that is, by decreasing the pressurized area.

Therefore, also in the pressure equalizing block 13 of this embodiment,
It can be seen that by arranging a plurality of hydraulic cylinders and pressurizing the lower die base unit 14 with a high surface pressure at the end surfaces of the plurality of rods 33, the occurrence of resin fluff and R can be suppressed.

In this embodiment, if the mold clamping force by the movable platen 4 is, for example, 150 (T) and is regularly used at 100% output, the load Q per hydraulic cylinder 81 to S5 is Q = 150 x 1000/N. (kg). Note that here, N indicates the number of hydraulic cylinders, and in FIG. 4, N=5.

Here, the diameter of the end surface of the rod 33 is φ=100 (mo)
Then, the internal pressure QI is QI=150X1000
/(π/ 4 x 1 0) x N(kg/c
m') come out.

For example, if the number of hydraulic cylinders is N=9,
The load is 15 to 30 (T) per hydraulic cylinder, and the internal pressure is about 200 to 350 (kg/cm2>). This is an appropriate value for evenly distributing the pressure to other hydraulic cylinders.

Next, a resin molding process using the resin molding apparatus 1 of this embodiment will be explained.

First, when the lead frame 30 is placed in each cavity 31 with the movable platen 4 positioned downward and the upper mold 18 and lower mold 15 opened, the platen driving The cylinder 11 is actuated and the movable platen 4 is raised.

In this way, the parting surfaces P of the lower mold 15 and the upper mold 18 are brought into close contact, and the mold clamping force is, for example, 150 (
When the temperature reaches T), a cylindrical tablet 8 made of semi-molten epoxy resin is introduced into the pot 20, the transfer cylinder 10 is activated, and the plunger 21 is moved downward in FIG. For example, 75 (Kgf/c
When a transfer pressure of about m') is applied, combined with heating by the heater 22 to about 180° C., the tablet 8 becomes a molten resin 8a and is transferred through the runner 27 to each gate 2.
8, the injection pressure is further increased and the injection pressure is increased by
High pressure is injected into the body.

At this time, stress may be locally applied to the lower mold 15 due to variations in the thickness of the lead frame 30, the mold clamping force of the movable platen 4, or the transfer pressure of the plunger 21 described above.

In FIG. 4, when a stress greater than +t is applied to the hydraulic cylinder S1 in the direction of the arrow in the figure compared to the pond portion, this +t force is applied to the rod 3 of the hydraulic cylinder S1.
It acts to push down the end face of 3. On the other hand, the hydraulic cylinder S1 is connected to the other hydraulic cylinders 82 to 82.
Since it has an interlocking structure through S5 and the flow pipe 32,
A reaction force of t15 acts on the end surfaces of the rods 33 of the full hydraulic cylinders S1 to S5. Therefore, the stress t locally applied to the hydraulic cylinder Sl is distributed to each of the hydraulic cylinders 81 to S5 and acts equally on the entire parting surface P. For this reason, the deformation of the lower die base unit 14 or the mold 15 due to the application of local stress and the resulting flatness error of the parting surface P are corrected, thereby suppressing the occurrence of resin flutter: LR.

In particular, according to this embodiment, stress can be uniformly distributed without requiring complicated mechanical control for each local area.

After the molten resin 8a injected into the cavity 31 under high pressure is cured by heating, the movable platen 4 is lowered under the control of the control unit 12, and the upper mold 18 and the lower mold 15 are opened.
The lead frame 30 with the package body 35 formed of the resin is taken out.

Such a lead frame 30 becomes a semiconductor device 43 shown in FIG. 1O by cutting and molding the leads 36 protruding from the package body 35 into a predetermined shape.

In the figure, 38 indicates a tab, and a semiconductor pellet 41 is mounted on the tab 38 via a bonding material 40 such as silver paste. The electrode pad 41a of the semiconductor pellet 41 and the inner lead (the part sealed inside the package body 35) of the lead 36 are made of conductive material such as gold (Au), copper (Cu), or aluminum (AI). The wire 42 is stretched in a loop shape, and the lead 36
Through this, it is possible to apply a power supply voltage to the semiconductor pellet 41 from the outside, output signals, and the like.

Although the invention made by the present inventor has been specifically explained above based on Examples, it goes without saying that the present invention is not limited to the above Examples and can be modified in various ways without departing from the gist thereof. Nor.

For example, although the number of hydraulic cylinders in the pressure equalizing block is five in FIG. 4 and nine in the description, it is of course not limited to these numbers.

Further, although hydraulic oil is used as the fluid filled in the cylinder, other types of fluid may be used.

In the above explanation, the invention made by the present inventor will be mainly described in terms of its field of application, which is the so-called flat package type (QFP: Quad Flat Pack).
e) The case where the application is applied to the resin molding process in a semiconductor device has been described, but the invention is not limited to this. For example, DIP (Dual In-1 In-1
e Package), P L CC (Plasti
c Leaded Chip Carrier),
S OJ (Small 0ut-'1ine J-b
It can also be applied to package structures such as end 1 ead).

〔Effect of the invention〕

A brief explanation of the effects obtained by representative inventions among the inventions disclosed in this section is as follows.

That is, by injecting the resin at high pressure while uniformly distributing the stress locally applied to the molding dividing plane of the mold, it is possible to prevent flatness errors in the molding dividing plane.

Furthermore, flatness errors in the molded dividing surfaces can be corrected without requiring highly accurate and complicated adjustment work.

These can prevent resin flash caused by gaps caused by flatness errors, and enable highly reliable package molding of resin-sealed semiconductor devices.

[Brief explanation of the drawing]

Fig. 1 is a cross-sectional view showing the vicinity of the mold of a resin molding device, which is an embodiment of the present invention; Fig. 2 is an overall configuration diagram of this resin molding device; Fig. 4 is a perspective view showing the pressure equalizing block; Fig. 5 is an explanatory diagram showing variations in the thickness of the lead frame; Figs. 6 and 7 are the thickness dimensions of the lead frame. An explanatory diagram showing the relationship between errors and the occurrence of resin flash. Figures 8 and 9 are explanatory diagrams showing the relationship between the pressing area for the mold and the occurrence of resin flash. Figure 10 is an illustration of the semiconductor obtained by this example. 11 is an explanatory diagram showing an outline of a resin molding device in the prior art, and FIG. 12 is a plan view showing a state in which resin flash occurs in a semiconductor device in the prior art. ■...Resin Mold device, 2... Fixed platen, 3
... Upper mold part, 4... Movable platen, 5... Lower mold part, 6... Device base, 7... Support, 8... Tablet, 8a... Molten resin, 10...Transfer fan ring, 11...Platen drive cylinder, 12...
Control unit, 13... pressure equalization block (pressure equalization mechanism), 14.
...lower pace unit, 14a...uniso +- book,
tt, 15...Lower mold, 16...Support pillar, 1
7... Upper mold base unit 7), 18... Upper mold, 20
... Pot, 21... Plunger, 22... Heater, 23... Heat insulation plate, 24... Backing plate, 25...
・Hydraulic oil, 26...Cal, 27...Runner, 28.
...gate, 30...lead frame, 31...cavity, 32...flow pipe (fluid flow pipe), 33...
・Rod, 34...stopper, 35...package body, 36...lead, 37...dam, 38...tab, 40...bonding material, 41...
Semiconductor pellet, 41a... Electrode pad, 42...
Wire, 43... Semiconductor device, 51... Movable platen, 52... Support pillar, 53... Lower die base unit, 54... Lower die, 55... Heater, 56...
・Upper mold base unit, 57... Upper mold, 58...
Cavity, 60... Pot, 61... Plunger, 62... Lead frame, 63... Tablet,
64...Runner, 65...Gate, 66...Lead, P...Parting surface, R...Resin flash, S1-S5...Hydraulic cylinder. Agent: Patent Attorney Daiwa Tsutsui

Claims (5)

[Claims] 1. When injecting resin at high pressure into multiple cavities formed on the molding dividing plane of a pair of upper and lower molds, the stress applied locally to the molding dividing plane of the mold is applied to the entire molding dividing plane. A method for manufacturing a semiconductor device, comprising forming a resin mold package corresponding to the shape of the cavity by uniformly dispersing the resin. 2. 2. The method of manufacturing a semiconductor device according to claim 1, wherein when stress is applied locally on a molding dividing plane of said mold, a pressing force opposing said stress is generated in said local area. 3. A resin molding device that forms a package corresponding to the shape of the cavity by high-pressure injection of resin into a plurality of cavities formed on a molding division plane of a pair of upper and lower molds, and the apparatus holds at least the mold or the mold. The base body is equipped with a pressure equalization mechanism consisting of a plurality of cylinders filled with fluid and connected to each other by fluid flow pipes, and each cylinder of the pressure equalization mechanism is connected to the mold or the base body by its respective rod end surface. A resin molding device characterized by supporting. 4. Claim characterized in that the fluid filled in the cylinder is oil, and each rod end face of each cylinder equally supports the molding dividing plane of the mold by hydraulic pressure transmitted by the fluid flow pipe. 3. The resin molding device according to 3. 5. 4. The resin molding apparatus according to claim 3, wherein the support surface of the pressure equalizing mechanism is provided with a stopper controlled to a predetermined height, and the maximum eccentric position of the rod end surface is controlled.