JPH07245368A - Lead frame for semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To eliminate lead strain and distortion, and enable simple and stable formation, by constituting a dumb bar and a fixing bar of the same thermoplastic insulating resin. CONSTITUTION:Leads 12 at the part positions turning to dumb bars 15 for preventing resin from flowing out at the time of molding and the part positions turning to fixing bars 16 for preventing distortion of inner leads 14 are coated with thermoplastic insulating resin by using a dispenser. After coating, the insulating resin is dried, and firstly the fixing bars 16 are formed. Secondly the dumb bars 15 are formed by making the thermoplastic insulating resin, out of the insulating resin, with which the parts to be the dumb bars 15 are coated flow into the parts between the leads 12 by heating and pressing. The insulating resin has dynamic elastic modulus higher than or equal to 10<7>dyn/cm<2> at the molding temperature, and has a low viscosity lower than or equal to 10<6> poise in the temperature range higher than the molding temperature. As the thermoplastic insulating resin having the above characteristics, polyimide, polyether amide, polyether amide imide, etc., are used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device lead frame and a method for manufacturing the same, and more particularly to a process for manufacturing a dam bar by composing a dam bar and a fixed bar of the same material and sharing a part of the manufacturing process. It relates to what forms a fixed bar.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 3, a lead frame has a tab 1 on which a semiconductor chip is mounted, and leads 2 extend in four directions from the outer periphery of the tab. Lead 2
Strictly speaking, the signal lead and the suspension lead supporting the tab are distinguished from each other, but here, they are simply referred to as the lead 2 without distinguishing them. The lead 2 has an inner lead 3 located on the tab 1 side and an outer lead 4 located on the opposite side of the tab 1.

The outer lead 4 is a dam bar 5 that crosses the outer lead 4.
The inner lead 3 is also fixed by a fixing bar 6 that crosses the inner lead 3.

As shown in the enlarged view of FIG. 4, the dam bar 5 is integrally formed with the outer lead 4 by the same metal material and is formed at the same time as the lead molding. This metal dam bar 5 is molded so that the molding resin 8 in the molding die 7 does not flow out from between the outer leads 4 when the semiconductor chip is mounted on the die and molding is performed as shown in FIG. It has the function of blocking the resin 8.

On the other hand, as shown in the enlarged view of FIG. 6, the fixing bar 6 has a tape-shaped polyimide film 6a attached on the inner lead 3 via an adhesive 6b. Generally, an inexpensive thermosetting resin is used as the adhesive.
The fixing bar 6 has an inner lead 3 with a floating tip.
Has a function of fixing the inner lead 3 and preventing the inner lead 3 from being deformed.

By the way, the dam bar made of metal must be separated in order to separate the leads after molding. Recently, the number of leads in the lead frame for logic ICs has increased, and the pitch is 0.5 to 0.3.
It has become as small as about mm. This dam bar is punched and removed by a metal mold, but the punching punch has a thin punch of about 0.2 mm, and the number is increasing. Therefore, after the punching, deformation of the lead such as bending and twisting occurs, and problems such as punching failure due to punch breakage and scoring with the die occur. Further, the initial investment amount of the mold, the complicated work required for maintenance, or the cost required for this increase, and the increase of this burden is also a serious problem.

Therefore, conventionally, in order to solve such a problem, a resin dam bar is formed by applying a soluble heat-resistant resin (polycarbonate, polyphenylene oxide, polysulfone, etc.) or an insulating resin, and after molding resin sealing. It has been proposed to melt the dam bar so that it can be easily removed, or to leave it as it is (for example, JP-A-4-91464 and JP-A-4-139868).

However, since a resin generally called a soluble heat resistant resin or an insulating resin has a high viscosity, when the resin is pressed between the leads, a force may be applied to the leads at the time of resin shaping, and the leads may be deformed. Further, since the viscosity is high, the resin cannot be sufficiently pushed between the leads, resin leakage may occur, and a good dam bar could not be stably formed. In particular, such lead deformation and resin leakage may be fatal in a lead frame having a large number of pins and a fine structure.

Therefore, a method is conceivable in which a thermosetting insulating resin that does not have such a problem is used as the resin for the dam bar and the separation after molding is unnecessary. In terms of using a thermosetting resin, the fixing bar made of a polyimide film attached with an adhesive also uses a thermosetting adhesive (eg, epoxy resin) as an adhesive for attachment. Therefore, a thermosetting resin of the same type as the thermosetting adhesive may be used as the dam bar.

[0010]

However, when the thermosetting resin is used for the dam bar, the following common drawbacks occur with the fixed bar which has already been used.

(1) Since it does not have heat resistance, the shape as a bus bar cannot be maintained at the temperature at the time of molding, and a gap is formed between the leads, and the resin outflow preventing function cannot be achieved.

(2) In addition to the time required for curing to cure,
Current leakage may occur due to outgas generated during curing, or wire bondability may deteriorate.

(3) Generally, the hardener in the thermosetting resin is likely to contain impurities, and the electric insulation is deteriorated due to the impurities, and a short circuit accident due to migration occurs.

An object of the present invention is to eliminate the drawbacks of the prior art described above by forming both the dam bar and the fixing bar with a thermoplastic resin, and to provide a lead frame for a semiconductor device which is inexpensive and has a high yield, and its manufacture. To provide a method.

[0015]

A lead frame for a semiconductor device according to the present invention comprises a dam bar provided between outer leads for preventing resin outflow during molding, and a fixing bar for fixing inner leads to prevent deformation of the inner leads. In the lead frame for a semiconductor device having the above, both the dam bar and the inner lead are made of a thermoplastic insulating resin.

According to the method of manufacturing a lead frame for a semiconductor device of the present invention, a portion to be a dam bar provided between outer leads for preventing resin outflow during molding and an inner lead for preventing deformation of the inner lead are fixed. The thermoplastic insulating resin is applied to the lead and the portion to be the fixed bar by a dispenser, respectively, and after the application, the thermoplastic insulating resin is dried to form the fixed bar first, and then the dried thermoplastic insulating resin Among them, the thermoplastic insulating resin applied to the portion to be the dam bar is hot pressed and poured between the leads to form the dam bar.

[0017]

In the present invention, both the dam bar and the fixed bar are made of thermoplastic insulating resin. A varnish-like thermoplastic insulating resin is applied to a predetermined portion to first form a fixed bar, and then hot press to form a dam bar. As the thermoplastic insulating resin, a resin having heat resistance, high purity and good workability such as polyimide or polyether amide imide is used. The dam bar is made of an insulating resin similarly to the fixed bar because it is not necessary to cut the dam bar after the resin is filled.

Regarding the heat resistance, it is important that this resin is hard up to about 200 ° C. near the mold temperature, has a strength enough to support the mold pressure, and softens in a temperature range exceeding this and can be easily shaped. . Therefore, a thermoplastic insulating resin having a dynamic elastic modulus of 10 ⁷ dyn / cm ² or more up to around the mold temperature and a low viscosity of 10 ⁶ poise or less in a temperature range higher than the mold temperature is preferable.

With respect to high purity, this resin is less likely to contain impurities, and in general, as compared with a curable resin in which impurities are likely to be contained, deterioration of electrical insulation due to impurities and a short circuit accident due to migration do not occur.

With respect to workability, this resin only needs to evaporate and dry the solvent contained in the resin, so that it takes time to cure the resin like a curable resin, or the curing is difficult. Occurrence of outgas that is sometimes generated does not cause deterioration of wire bondability. From these points, the thermoplastic resin is preferable to the thermosetting resin.

By the way, when the dam bar is made of a thermoplastic insulating resin satisfying the above requirements, heating at about 200 ° C. is performed for drying the resin and hot press molding. Therefore, it is necessary to provide the fixed bar near the dam bar with the same heat resistance. As a result, if the fixed bar is made of the same resin as that of the dam bar, both bars can be formed by the same method, so that they can be formed more easily than when they are formed individually.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a lead frame for a semiconductor device of the present invention will be described below with reference to FIG. FIG. 1 shows a dam bar 15 and a fixed bar 1 formed on a lead 12 according to this embodiment.
6 shows an enlarged perspective view of FIG.

The dam bar 15 is made of a thermoplastic insulating resin 10 and is provided between the outer leads 14 in order to prevent the resin from flowing out at the time of molding. The outer leads 14 are connected to each other with the same thickness as the lead thickness. There is. On the other hand, the fixing bar 16 is also made of the thermoplastic insulating resin 10 and is provided in a tape shape on the inner lead 13 to prevent the inner lead 13 from being deformed.
Is fixed so that it does not move.

In order to provide the dam bar 15 and the fixed bar 16, first, the thermoplastic insulating resin 10 is formed in stripes on the outer lead 14 which is to be the dam bar and the inner lead 13 which is to be the fixed bar. Apply a fixed amount. After application, thermoplastic insulating resin 1
0 is dried to first form the tape-shaped fixing bar 16.

If the dam bar 15 is simply dried, the excess insulating resin 10 remains applied to the lead surfaces other than the gaps between the leads 14. If this is left as it is, the insulating resin on the surface of the leads will interfere, and a gap will be created between the cavity and the lead during resin sealing that will be performed later. , The resin outflow prevention function of the dam bar cannot be exerted.

Therefore, after the insulating resin is dried, a pressing pressure is applied to the lead coating portion by pressing to push the excess insulating resin on the lead surface into the spaces 3 between the leads so that the lead surface and the insulating resin are flush with each other. , Do not leave the insulating resin on the lead surface.

At the time of this press working, if excessive force is applied to the leads, the leads may be deformed, so heat is applied at the same time. The heating temperature is higher than that during drying so that the thermoplastic resin can easily flow.

In this way, it is possible to effectively prevent a force from being applied to the leads during resin shaping, and to form a good dam bar without lead deformation in a stable manner between the leads. Since the dam bar is made of an insulating resin like the fixed bar, it is not necessary to remove the dam bar even after resin sealing.

The thermoplastic insulating resin 10 forming both the dam bar and the inner lead has a large dynamic elastic modulus at the mold temperature in order to stabilize the coating. Further, in order to shape at a temperature higher than the mold temperature after coating, a material having a low viscosity in a temperature region higher than the mold temperature is used. Polyimide, polyether amide, polyether amide imide and the like are suitable as the thermoplastic insulating resin having such characteristics.

Next, a specific example of the above-mentioned embodiment will be described. The lead frame is 42 alloy, plate thickness T0.2mm, outer lead pitch P0.5mm, outer lead width W
0.2 mm, outer lead spacing D 0.3 mm.

The thickness t of the dam bar is 0.2 mm, which is the same as that of the outer lead 14, and the width w in the lead length direction is 0.5 to 1.0 mm.
And is embedded between the outer leads 14. The thickness t'of the fixing bar is 0.1 to 0.5 mm, and the width w'in the lead length direction.
Is about 0.5 mm and is attached to the inner lead 13 in a tape shape.

The thermoplastic insulating resins used are both polyether amide imides, specifically, trade name HM-1.
(Hitachi Chemical Co., Ltd.) was used. As shown in FIG.
Glass transition temperature T of the polyether amide imide used
g is around 230 ° C. 10 ¹⁰ at temperatures below Tg
It has a dynamic elastic modulus of dyn / cm ² or more, softens at a temperature of 250 ° C. or more, and has a viscosity of 10 ⁶ poise or less.

In this specific example, first, a portion of the lead frame to be the dam bar and a portion of the lead frame to be the fixed bar are
A varnish-like thermoplastic insulating resin containing a solvent is continuously extruded with a dispenser in a fixed amount and applied. At this time, only one side is applied to the lead of the portion to be the fixed bar, but both sides are applied to the lead of the portion to be the dam bar.

Next, after evaporating the solvent at a temperature of about 100 to 200 ° C. to dry the thermoplastic insulating resin, only the thermoplastic insulating resin at the dam bar portion is pressed from above and below by a hot press at about 250 ° C., and between the leads. Pour resin into and shape. At this time, in order to prevent the lead from being deformed by applying a force during shaping by hot pressing, it is important to perform the heating at a temperature of about 250 ° C. at which the resin easily flows.

[0035]

【The invention's effect】

(1) According to the invention described in claim 1, by using the thermoplastic insulating resin together, the dam bar and the fixing bar which are inexpensive and have a good finished yield can be stably produced without causing distortion or deformation of the leads. Can be formed.

(2) According to the second aspect of the invention, since the fixed bar is formed when the bus bar is formed, it can be formed more easily.

(3) According to the invention described in claim 3, since the thermoplastic insulating resin is limited to one having a predetermined characteristic at a predetermined temperature, a better dam bar and a fixed bar can be stably formed. You can do it.

(4) According to the invention described in claim 4, since inexpensive polyimide, polyether amide, or polyether amide imide is used as the thermoplastic insulating resin, the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is a partially enlarged perspective view of a dam bar and a fixing bar for explaining an embodiment of a semiconductor device lead frame of the present invention.

FIG. 2 is a temperature characteristic diagram of elastic modulus of the polyether amide imide used in this example, in which the horizontal axis represents temperature (° C.) and the vertical axis represents elastic modulus (dyn / cm ² ) on a logarithmic scale. .

FIG. 3 is a plan view showing the overall structure of a conventional lead frame.

FIG. 4 is a partially enlarged perspective view illustrating the structure of a conventional dam bar.

FIG. 5 is a partial cross-sectional view illustrating a situation at the time of molding.

FIG. 6 is a partially enlarged perspective view illustrating a structure of a conventional fixed bar.

[Explanation of symbols]

 10 Thermoplastic Insulation Resin 13 Inner Lead 14 Outer Lead 15 Dam Bar 16 Fixed Bar

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 23/28 A 8617-4M

Claims (4)

[Claims] 1. In a lead frame for a semiconductor device having a dam bar for preventing resin outflow during molding and a fixing bar for preventing deformation of the inner leads, both the dam bars and the inner leads are made of thermoplastic insulating resin. A lead frame for a semiconductor device, which is characterized in that 2. A thermoplastic insulating resin is applied by a dispenser to the leads of a portion to be a dam bar for preventing resin outflow during molding and a portion to be a fixing bar for preventing deformation of the inner leads, respectively. After coating, the thermoplastic insulating resin is dried to form the fixing bar first, and then the thermoplastic insulating resin applied to the portion of the dried thermoplastic insulating resin that is to become the dam bar is heated and pressed between the leads. A method for manufacturing a lead frame for a semiconductor device, characterized by forming a dam bar by pouring into a substrate. 3. The thermoplastic insulating resin has a dynamic elastic modulus of 10 ⁷ dyn / cm ² or more up to the mold temperature and a low viscosity of 10 ⁶ poise or less in a temperature range higher than the mold temperature. The method of manufacturing a lead frame for a semiconductor device according to claim 1 or the lead frame for a semiconductor device according to claim 2. 4. The lead frame for a semiconductor device according to claim 1, wherein the thermoplastic insulating resin is made of polyimide, polyether amide or polyether amide imide, or claim 2 or 3. Manufacturing method of lead frame for semiconductor device.