JPH07245373A - Lead frame for semiconductor device and its manufacture - Google Patents

Abstract

PURPOSE:To eliminate lead distortion at the time of molding, and restrain lead flatness and lead bending after lead shaping in the range lower than or equal to allowable values, by regulating the upper limit of the thickness of a thermoplastic insulating resin on the lead surface at the coating part position turning to a dumb bar. CONSTITUTION:Dumb bars 3 are formed between leads 2 by spreading insulating resin 4 on the leads 2. The insulating resin 4 turning to the dumb bar 3 is spread in lines type on the leads 2 with a dispenser 5. The resin is dried by heating and evaporating solvent with a hot plate 6. The part positions coated with the resin 4 are sandwiched by polymer films 7 easy to be peeled. The resin 4 is heated and pressed from both sides by the plates 6, 8, and made to flow with pressure into the part between the leads 2, 2. The temperature or the pressure is so controlled that the gap M between an upper metal mold and a lower metal mold satisfies the relation M<=T+2(10mum+tF) where T is the lead thickness and tF is the film thickness. Thereby the thickness of the thermal plastic insulating resin on the single surface of the lead at the part position coated with the insulating resin is set lower than or equal to 10mum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lead frame for a semiconductor device and a method for manufacturing the same, in which a dam bar made of an insulating resin is formed between leads so that the dam bar does not have to be removed after molding, and more particularly to an outer frame. The present invention relates to a multi-pin lead frame having a very narrow lead pitch, which prevents lead deformation during molding.

[0002]

2. Description of the Related Art In a lead frame used for a semiconductor device with a molded package, leads are provided in four directions,
Moreover, a multi-pin lead frame having lead terminals whose outer lead pitch is 0.5 mm or less has been developed.

As shown in FIG. 4, in the conventional lead frame 1, since the leads 2 and 2 are integrally connected by a metal dam bar 3 made of the same material as the leads 2, the dam bar 3 after molding is connected. Although it must be cut in order to divide it, as the number of pins increases and the spacing between leads becomes narrower, it becomes difficult to cut the dam bar.

Therefore, a method has been proposed in which an insulating resin is applied to the leads and then dried to replace the metal dam bar.

[0005]

However, the conventional method of providing an insulating resin instead of the metal dam bar has the following problems.

As shown in FIG. 5, if the insulating resin 4 is applied and then dried to form the dam bar 3, the insulating resin 4 is largely left on the surface of the lead 2.

If much insulating resin 4 remains on the surface of the lead 2 in this way, the dam bar 3 coated with the resin is sandwiched by the molding die during resin molding. Since the resin 4 apparently increases the thickness of the lead 2, when the resin 2 is crushed by the molding die, the lead 2 coated with the resin 4 is also crushed and deformed.

After molding, the outer leads are shaped according to the mounting form, but if the leads are deformed during molding, accurate lead shaping cannot be performed, and the lead flatness and lead bending after shaping are bad. Here, the flatness indicates the amount of displacement of each lead in the lead thickness direction when the semiconductor device after lead shaping is placed on a horizontal plate. Further, the lead bending indicates the displacement amount after shaping with respect to the design value in the width direction of each lead.

The object of the present invention is to eliminate the above-mentioned drawbacks of the prior art by defining the thickness of the thermoplastic insulating resin on one surface of the lead at the application site, and to improve the lead flatness and lead bending after lead shaping. Another object of the present invention is to provide a lead frame for a semiconductor device and a method for manufacturing the same.

[0010]

A semiconductor device lead frame according to the present invention is a semiconductor device lead frame in which a thermoplastic insulating resin is applied to the leads and a dam bar is provided between the leads, to which the thermoplastic insulating resin is applied. The thickness of the thermoplastic insulating resin on one surface of the lead of the portion is 10 μm or less.

Further, the method for manufacturing a lead frame for a semiconductor device of the present invention has a step of applying a thermoplastic insulating resin to the leads to provide a dam bar between the leads, and the step of applying the thermoplastic insulating resin to be the dam bar to the leads. After application, the solvent contained in the thermoplastic insulating resin is evaporated to dry the insulating resin, and after drying, the site coated with the thermoplastic insulating resin is
It is sandwiched between a thermoplastic insulating resin and a heat-resistant polymer film that can be easily peeled off, and the thermoplastic insulating resin is pushed between the leads by heat press molding with upper and lower molds from both sides so that the gap between the upper and lower molds satisfies the following formula. Where M ≦ T + 2 (10 μm + t _F ), where M is the gap between the upper and lower molds, T is the thickness of the lead, t _{F is} the thickness of the heat-resistant polymer film, and the thermoplastic insulating resin is controlled by controlling the temperature or pressure. The thickness of the thermoplastic insulating resin on one surface of the lead at the portion coated with is 10 μm or less.

[0012]

In the lead frame of the present invention, the thickness of the thermoplastic insulating resin on one surface of the lead at the portion coated with the thermoplastic insulating resin is 10 μm or less. If the thickness of the thermoplastic insulating resin is 10 μm or less, the apparent thickness of the lead due to the insulating resin becomes small, so there is no lead deformation due to the mold during molding, and lead flatness after lead shaping due to lead deformation. Is favorable and lead bending is reduced.

The material of the lead frame may be 42 alloy, Cu alloy or the like, and the shape of the lead frame may be DIP (Dual In Line Package) or QFP (Quad Fla).
t Package) or the like.

The plate thickness of the lead frame is not particularly limited, but it is effective that the thickness of the outer lead, which is the portion to which the thermoplastic insulating resin is applied, be 0.08 to 0.3 mm.
This is because if the thickness is 0.08 mm or less, the lead deformation at the time of molding cannot be controlled depending on the thickness of the resin at the site, and if it is 0.3 mm or more, the lead deformation does not become a problem. The outer lead pitch is not particularly limited, but it is effective to apply it to a lead frame having a fine pitch of 0.5 mm or less in order to clear the allowable value of lead bending after lead shaping.

Further, in the method of manufacturing the lead frame of the present invention, the solvent in the insulating resin is evaporated after the thermoplastic insulating resin which becomes the dam bar is applied to the leads and before shaping.
This is because it is necessary to let the solvent escape in advance because the coating part is sandwiched by the heat resistant polymer film during shaping. In addition, the part coated with the thermoplastic insulating resin,
When the coated portion is sandwiched by the heat-resistant polymer film, the insulating resin is smoothly moved between the leads, and pressure is softly applied to the leads, so that the leads are not deformed during resin shaping.

The thickness of the heat-resistant polymer film is preferably about the thickness of the lead at the application site or thinner than the lead, particularly about 0.1 mm, from the viewpoint of ensuring the flatness of the insulating resin between the leads. A polyimide film is preferable in terms of heat resistance, releasability, and flatness.

[0017]

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. The lead frame of this embodiment has 42 alloys, the lead 2 has a plate thickness T of 0.15 mm, the outer lead pitch P is 0.5 mm, and the outer lead width W.
Is 0.2 mm and the outer lead spacing D is 0.3 mm, 20
It is an 8-pin QFP (Quad Flat Package). Also,
The thermoplastic insulating resin 4 is a varnish-like polyether amide imide having a glass transition temperature of about 200 ° C., and HM-1 (trade name) manufactured by Hitachi Chemical Co., Ltd. was used.

FIG. 1E is a sectional view of the lead frame of the dam bar portion after the dam bar is formed. The dam bar 3 of the lead frame is provided between the leads 2 and 2 by applying the thermoplastic insulating resin 4 to the leads 2. . The thickness t of the thermoplastic insulating resin 4 on one side (one side) of the surface of the lead 2 coated with the thermoplastic insulating resin 4 is 10 μm or less. The thickness of the other is 20 μm or less. An example of a method of manufacturing the dam bar with the insulating resin 4 on the lead frame is as follows.

First, a varnish-like thermoplastic insulating resin 4 is linearly applied on the leads by a dispenser 5 so as to cross between the leads 2 at the portion to be the dam bar (FIG. 1).
(A)). This coating is applied to both sides of the lead 2. Next, the solvent contained in the insulating resin 4 in a large amount is evaporated on the hot plate 6 of about 200 ° C. that constitutes the lower mold to dry the insulating resin (FIG. 1B).

After drying, the coated portion of the insulating resin 4 of the lead frame 1 is sandwiched between the insulating resin 4 and a material that is easily peeled off, here polyimide films 7 and 7 having a thickness of 0.1 mm (FIG. 1C). .

Further, heat and power are applied from both sides by the hot plates 8 and 6 of 250 ° C. which constitute the upper and lower molds. As a result, the insulating resin 4 on the lead 2 is washed away between the leads 2 and 2 to uniformly fill the space between the leads 2 and 2 with the insulating resin 4 (FIG. 1 (d)).

Then, the films 7, 7 are peeled off to obtain the above-mentioned lead frame having the dam bar 3 made of the insulating resin 4 having a smooth surface (FIG. 1 (e)).

The thickness t of the insulating resin 4 on the lead surface when the dam bar 3 is made of the insulating resin 4 by the method described above.
2 and 3 show the results of examination in lead shaping after resin molding. The thickness of the insulating resin at the site was changed by adjusting the amount of insulating resin applied or the temperature and pressure (temperature or pressure, or temperature and pressure) by a hot plate. For the thickness of the insulating resin at the relevant portion, a displacement sensor (not shown) for measuring the gap between the dies is provided between the upper and lower dies to be pressed, and the thickness of the lead frame is subtracted from the measured value of the displacement sensor. It was calculated as a value obtained by subtracting the thickness of the film (thickness of one sheet) from the value halved.

[0024] t = 1/2 (M- T) -t F (1) where, t: thickness of the insulating resin M: the gap between the upper and lower molds (the measured value of the displacement sensor) T: the lead thickness t _F : Film Thickness FIG. 2 shows the relationship between the resin thickness on the lead surface and the lead flatness after shaping. The resin thickness was measured by microscopic observation of the cross section, and the lead flatness was measured by an optical focusing microscope. As can be seen from these results, the flatness of the leads, that is, the displacement amount, increases as the resin thickness on the lead surface increases. After the lead is shaped, the semiconductor device is to be mounted on a circuit or device that uses the semiconductor device. At this time, it is desirable that the flatness of the lead be 75 μm or less. Was 10 μm or less.

Next, FIG. 3 shows the relationship between the resin thickness on the lead surface and the lead bending after shaping. The lead bend was defined as the lead displacement from the design value, and the displacement was measured with a tool microscope to obtain the lead bend. As you can see from the result, as the resin thickness on the lead surface becomes thicker,
The lead bend, that is, the amount of displacement is large. In the case where the outer lead pitch P is 0.5 mm as in this embodiment, the lead bending of ± 100 μm or less is practical.
The resin thickness satisfying that value was 20 μm or less. However, when the outer lead pitch is 0.3 mm, the allowable value of lead bending is about ± 50 μm, which satisfies the requirement that the resin thickness is 10 μm or less.

As described above, when the thickness of the insulating resin on the surface of the lead is 10 μm or less, the lead is prevented from being deformed by applying an unnecessarily large force to the lead at the time of molding, and the lead flatness after shaping. Both the lead bending and the lead bending can satisfy the allowable value of the multi-pin lead frame.

[0027]

【The invention's effect】

(1) According to the invention described in claim 1, since the thickness of the insulating resin in the relevant portion is 10 μm or less, there is no lead deformation during molding, the lead flatness after lead shaping is good, and the lead bending is small. .

(2) According to the invention described in claim 2, since the thickness of the lead at the relevant portion is set to 0.08 to 0.3 mm,
The thickness of the insulating resin whose upper limit value is defined works effectively for preventing lead deformation during molding, and is particularly effective for improving lead flatness and lead bending after lead shaping.

(3) According to the invention described in claim 3, since the pitch of the leads of the relevant portion is set to 0.5 mm or less, the thickness of the insulating resin that defines the upper limit value prevents the lead from being deformed during molding. It works effectively, and it is possible to sufficiently clear the lead flatness after lead shaping as well as the lead bending tolerance after shaping required for a lead frame having a lead pitch of 0.5 mm or less.

(4) According to the invention described in claim 4, the solvent in the insulating resin is evaporated and dried before the insulating resin coating portion is sandwiched between the polymer films, and the coating portion is covered with the polymer film. Since heating and pressurization are performed after sandwiched by, it is possible to effectively prevent resin leakage at the time of molding, in combination with defining the upper limit of the thickness of the thermoplastic insulating resin on one surface of the lead.

[Brief description of drawings]

FIG. 1 is a process drawing of a dam bar for explaining an embodiment of a lead frame for a semiconductor device of the present invention.

FIG. 2 is a relationship diagram between the resin thickness of the lead surface and the flatness of the lead after shaping in the present embodiment.

FIG. 3 is a diagram showing the relationship between the resin thickness of the lead surface and the lead bending after shaping in the present embodiment.

FIG. 4 is an external view of a lead frame having a conventional metal dam bar and an enlarged view of a dam bar portion.

FIG. 5 is a cross-sectional view of a dam bar portion after drying of a lead frame having a dam bar of an insulating resin of a conventional example.

[Explanation of symbols]

 2 Lead 3 Dam bar 4 Thermoplastic insulating resin 5 Dispenser

Claims (4)

[Claims] 1. In a lead frame for a semiconductor device in which a thermoplastic insulating resin is applied to the leads and a dam bar is provided between the leads, the thickness of the thermoplastic insulating resin on one surface of the lead at the portion to which the thermoplastic insulating resin is applied is adjusted. A lead frame for a semiconductor device, which has a thickness of 10 μm or less. 2. The lead frame for a semiconductor device according to claim 1, wherein the thickness of the lead at the portion coated with the thermoplastic insulating resin is 0.08 to 0.3 mm. 3. The lead frame for a semiconductor device according to claim 1 or 2, wherein the pitch of the lead at the portion coated with the thermoplastic insulating resin is 0.5 mm or less. 4. A step of applying a thermoplastic insulating resin to the leads to provide a dam bar between the leads, the solvent being contained in the thermoplastic insulating resin after applying the thermoplastic insulating resin to be the dam bar to the leads. Is evaporated to dry the insulating resin, and after drying, the portion coated with the thermoplastic insulating resin is
It is sandwiched between a thermoplastic insulating resin and a heat-resistant polymer film that is easy to peel off, and the thermoplastic insulating resin is pushed between the leads by heat press molding with upper and lower molds from both sides, and the gap between the upper and lower molds is To satisfy M ≦ T + 2 (10 μm + t _F ), where M: gap between upper and lower molds T: lead thickness t _F : thickness of heat-resistant polymer film The thermoplasticity is controlled by controlling temperature or pressure. A method for manufacturing a lead frame for a semiconductor device, characterized in that the thickness of the thermoplastic insulating resin on one surface of the lead at the portion coated with the insulating resin is 10 μm or less.