JPH1084008A - Burr removing method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove at low cost the burrs formed on the lead frame after a mold sealing operation. SOLUTION: A stopper part 2a, corresponding to the lead part 1a of the lead frame 1, on which a mold sealing process is finished, is formed, and using a burr-removing device, having a frame retaining material 2 which retains the lead frame 1 detouring a mold part 1b and a pressing part 3 with which the mold part 1b is displaced and the lead part 1a is warped by pressing it to the stopper 2a, the burrs 5 are removed by adding stress.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique which is effective when applied to removal of burrs formed on a lead frame by mold sealing.

[0002]

2. Description of the Related Art When a lead frame on which a semiconductor chip is mounted is molded and sealed, resin may ooze out from a slight gap between the lead frame and a mold. Also,
The space surrounded by the outer lead and the dam bar is filled with resin for the thickness of the lead frame. These resins,
That is, if the burrs are peeled off particularly after the exterior treatment, the base material of the lead frame is exposed, and the solder wettability and corrosion resistance of the outer lead are impaired. Therefore, when the mold sealing step is completed, it is necessary to sufficiently remove burrs.

Here, for example, “Practical Course VLSI Packaging Technology (2)” published by Nikkei BP (1993)
May 31), as described on pages 41 to 43,
A typical example of the deburring method is an inner diameter that performs a high-speed circular motion.
There is a hydraulic honing method in which pressurized water is sprayed onto burrs from a thin nozzle of about 0.2 mm.

[0004]

[SUMMARY OF THE INVENTION However, according to this hydraulic honing, water pressure 300kg · f / cm ² at a minimum, since the higher also reach 1000kg · f / cm ² at maximum,
Deburring devices are extremely expensive and large in size.

[0005] In this case, the deburring cost increases, and
It is not preferable because the space efficiency of the device is deteriorated.

An object of the present invention is to provide a technique capable of removing burrs formed on a lead frame after mold sealing at low cost.

Another object of the present invention is to provide a technique capable of removing burrs formed on a lead frame after mold sealing with a compact deburring device.

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.

[0009]

SUMMARY OF THE INVENTION Among the inventions disclosed in the present application, the outline of a representative one will be briefly described.
It is as follows.

That is, the deburring method according to the present invention comprises:
The lead portion of the lead frame after the mold sealing step is warped, and a burr formed in the mold sealing step is stressed in advance and then removed.

In this deburring method, a pressure may be applied to the burr at the same time as a pressure is applied to the burr. In this case, it is desirable to apply pressure intermittently.

Further, the method of removing burrs according to the present invention is characterized in that the burrs are removed while warping the lead portions of the lead frame after the mold sealing step to apply stress to the burrs formed in the mold sealing step. It is assumed that.

In these deburring methods, the burrs are removed by electrolysis in an alkaline solution to remove the burrs with H ₂ gas generated by electrolysis, and chemical treatment in which the burrs are swollen and removed by an organic solvent. At least one of a hydraulic honing method in which a pressurized water is sprayed onto a burr to remove the burr, a liquid honing method in which an abrasive mixed aqueous solution is sprayed in a burr at a high pressure, and a dry honing method in which a burr is removed with a dry abrasive or a brush. This can be done using one method.

In the deburring apparatus according to the present invention, a stopper portion is formed opposite to the lead portion of the lead frame after the mold sealing step, and the lead frame is held so as to avoid the mold portion of the lead frame. And a pressing portion for displacing the mold portion, pressing the lead portion against the stopper portion, and warping the lead portion to apply a stress to a burr formed on the lead frame.

In this deburring apparatus, the stopper portions are formed on both sides of the lead portion, and the pressing portions displace the mold portions in mutually different directions so that the lead portions are pressed against the respective stopper portions.

Further, the frame holding member may be formed of a hollow pipe material, and the stopper may have an ejection hole for ejecting the ejection body toward the burr. It is desirable that the ejector ejects intermittently.

According to the above-described means, a good deburring effect can be obtained, and deburring can be easily performed. As a result, an expensive device having a large power is not required, and burrs can be removed at low cost. Further, since only a compact device is required, the space efficiency of the device can be improved.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings. In all the drawings for describing the embodiments, the same members are denoted by the same reference numerals, and the description thereof will not be repeated.

FIG. 1 is a front view showing a deburring apparatus according to an embodiment of the present invention, FIG. 2 is a side view of FIG. 1, FIG. 3 is an explanatory view showing burrs formed on a lead frame, and FIG. FIG.
It is explanatory drawing which shows the burr removed by the deburring apparatus of FIG.

In this embodiment, for example, a surface mount type QFP (Quad FQ) having lead portions 1a extending in four directions is formed.
lat Package) type lead frame 1, and four places of the lead frame 1 after the mold sealing process are completed.
A molded portion 1b in which a semiconductor chip is sealed with a resin is formed. However, in the present invention, various lead frames can be applied, and the present invention is not limited to the QFP described in the present embodiment.

The deburring apparatus has a frame holding member 2 made of, for example, SUS having corrosion resistance. The frame holding member 2 has a stopper portion 2a formed to face the lead portion 1a so as to avoid the mold portion 1b. As shown in FIG. 2, the stopper 2a is formed on both sides of the lead 1a, and the end of the lead frame 1 is brought into contact with a connecting portion 2b connecting these two stoppers 2a. The right and left sides are regulated, and it is held in an inverted posture. However, the stopper 2a may be formed only on one side of the lead 1a. in this case,
On the side where the stopper 2a is not provided, a posture restricting portion for supporting the lead frame 1 and preventing the lead frame 1 from falling is provided.

Pressing portions 3 having pressing protrusions 3a (FIG. 2) projecting toward the mold portions 1b are provided on both sides of each of the mold portions 1b. The pressing portion 3 is attached to a shaft portion 4 provided below the lead frame 1 along the lead frame 1 so as to swing. Therefore, when the pressing protrusion 3a of the pressing portion 3 swings and comes into contact with the mold portion 1b, the molding portion 1b
Is displaced in a direction perpendicular to its surface. The lead portion 1a is moved to the stopper portion 2a by the displaced mold portion 1b.
, And warping occurs when further displaced. As a result, as shown in FIG.
The burrs 5 formed near the mold portion 1b and the burrs 5 formed in the space surrounded by the lead portion 1a and the dam bar 1c are stressed.

When the pressing portion 3 swings in the opposite direction,
The mold portion 1b is pressed by the pressing protrusion 3a on the opposite side to the previous one, and the opposite surface of the lead portion 1a is pressed against the other stopper portion 2a, and warpage occurs in the opposite direction.

The pressing portion 3 only needs to be capable of displacing the mold portion 1b so that the lead portion 1a is warped, and does not necessarily have to swing as in this embodiment. . When the stopper 2a is formed only on one side of the lead 1a as described above,
The pressing protrusion 3a is also formed only on one side where the lead portion 1a is pressed against the stopper portion 2a.

The frame holding member 2 is made of a hollow pipe material. The stopper portion 2a is provided with an ejection hole 7 (FIG. 4) through which an ejection body 6 such as a gas or a liquid is ejected toward the burr 5. Therefore, the burr 5 stressed by the warpage of the lead portion 1a
Is forcibly separated from the lead frame 1 by the ejector 6. It is preferable that the ejector 6 be ejected intermittently so that the burr 5 is more effectively peeled off.
However, such a jet is not always necessary, and the burr 5 may be removed only by the stress caused by the warpage of the lead portion 1a.

Here, by using the frame holding member 2 as an electrode for electrolysis, a function as an electrolysis apparatus is also provided, and the H ₂ gas generated by immersion in an alkaline solution ensures the separation of the burr 5. Can also. In this case, it is desirable to use a gas that does not adversely affect the alkaline solution, such as air or an inert gas, for example. The deburring by electrolysis may be performed after applying stress to the burr 5, or may be performed while applying stress.

With the deburring apparatus having the above configuration,
The burrs 5 formed on the lead frame 1 are removed as follows.

First, a lead frame 1 for which a mold sealing step has been completed is prepared, and the lead frame 1 is set on the frame holding member 2 such that the lead portion 1a faces the stopper portion 2a.

Next, as shown in FIG. 4, the pressing portion 3 is swung to displace the mold portion 1b to the left side in the drawing by the pressing protrusion 3a, and the lead portion 1a is pressed against the stopper portion 2a to generate warpage. Let it. As a result, stress is applied to the burrs 5 that extend from the mold portion 1b and adhere to the leads 1a, and the burrs 5 formed on the right side of the leads 1a in FIG. The formed burr 5 is separated from the contact surface with the lead portion 1a. When the mold portion 1b is displaced to the opposite side to cause the lead portion 1a to be warped in the opposite direction, the burr 5 formed on the left side is cracked, and the burr 5 formed on the right side is separated from the lead portion 1a. I do.

Further, as shown in the drawing, a greater stress is applied to the burr 5 by spraying the ejector 6 from the ejection hole 7 to the burr 5 deformed by applying stress due to the warpage of the lead portion 1a. .

After stress is applied to the burrs 5 formed in the mold sealing step in this way, the burrs 5 are removed. For removal, an electrolytic method, a chemical treatment method, a hydraulic honing method, a liquid honing method, a dry honing method, or the like is used.

[0032] Here, the electrolytic method, dipping the deburring device in an alkaline solution, for example, the electrode is a frame holding member 2 over the electrolyte to generate H ₂ gas, burr 5 This H ₂ gas Float and remove. In the chemical treatment method, for example, the lead frame 1 is immersed in an organic solvent such as N-methylpyrrolidone to chemically swell and remove the burrs 5. The hydraulic honing method removes burrs 5 by a pressurized water injection method. The burrs 5 to which stress has been applied in advance can be completely removed with an extremely low water pressure of about 50 to 100 kg · f / cm ^2. Become. In the liquid honing method, an aqueous solution in which an abrasive is mixed is ejected at a high pressure to burrs 5 to remove the same. And
The dry honing method is to remove the burrs 5 with a dry abrasive or a brush.

Although the deburring is performed by using any one of these, a plurality of removing means may be used in combination as required. That is, the burrs can be removed by using at least one of the above-described removing means. Instead of removing the burrs 5 after applying the stress, the burrs 5 may be removed while applying the stress.

As described above, according to the deburring technique of the present embodiment, the lead portion 1a is warped to apply a stress to the burr 5 in advance, or to remove the burr 5 while applying the stress. Therefore, deburring can be easily performed. Thus, for example, even in the case of the hydraulic honing method, the burr 5 can be removed with a low water pressure of about 50 to 100 kg · f / cm ² .

Therefore, an expensive device having a large power is not required, and the burr 5 can be removed at low cost. In addition, since a compact device is enough,
The space efficiency of the device can be improved.

Although the invention made by the inventor has been specifically described based on the embodiment, the invention is not limited to the embodiment, and various modifications may be made without departing from the gist of the invention. It goes without saying that it is possible.

For example, in the present embodiment, the burr is stressed by inverting the lead frame. However, the burr may be stressed from above and below in a lying state.

[0038]

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

(1) According to the deburring technique of the present invention, the lead portion is warped to apply stress to the burr in advance,
Alternatively, since this is removed while applying a stress, a good burr floating effect can be obtained, and deburring can be easily performed.

(2) According to the above (1), an expensive device having a large power is not required, and burrs can be removed at low cost.

(3) According to the above (1), since a compact device is sufficient, the space efficiency of the device can be improved.

(4) When the deburring technique of the present invention is used together with the hydraulic honing method, it is possible to sufficiently and quickly remove burrs even with a device having a low water pressure of about 50 to 100 kg · f / cm ^2. it can. According to the present invention, both the apparatus cost and the processing time can be reduced by about 50% as compared with the conventional hydraulic honing.

(5) If the deburring is performed in parallel with the deburring by applying a stress, the time required for the deburring can be further reduced.

[Brief description of the drawings]

FIG. 1 is a front view showing a deburring apparatus according to an embodiment of the present invention.

FIG. 2 is a side view of FIG.

FIG. 3 is an explanatory view showing burrs formed on a lead frame.

FIG. 4 is an explanatory view showing burrs removed by the deburring apparatus of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lead frame 1a Lead part 1b Mold part 1c Dam bar 2 Frame holding material 2a Stopper part 2b Connection part 3 Press part 3a Press protrusion 4 Shaft part 5 Burr 6 Injector 7 Jet hole

Claims (9)

[Claims] 1. A burr formed by warping a lead portion of a lead frame after a mold sealing step to apply a stress to burrs formed in the mold sealing step in advance, and thereafter removing the burrs. How to take. 2. The deburring method according to claim 1, wherein
A deburring method, wherein a stress is applied to the burr and a pressure is applied to the burr by a jet. 3. The deburring method according to claim 2,
A deburring method, wherein intermittent pressure is applied to the burr. 4. A method for removing burrs, wherein the burrs are removed while warping a lead portion of a lead frame after the mold sealing step to apply stress to burrs formed in the mold sealing step. 5. The deburring method according to claim 1, wherein the burr is removed by (a) floating the burr with H ₂ gas generated by electrolysis in an alkaline solution. (B) a chemical treatment method in which the burr is removed by swelling with an organic solvent, (c) a hydraulic honing method in which pressurized water is injected into the burr to remove the burr, and A deburring method characterized by using at least one of a liquid honing method in which the burrs are sprayed with high pressure to remove the burrs, and (e) a dry honing method in which the burrs are removed with a dry abrasive or a brush. . 6. A frame holding member for holding a lead frame so as to avoid a mold portion of the lead frame, wherein a stopper portion is formed opposite to the lead portion of the lead frame after the mold sealing step. A deburring device, comprising: a pressing portion for displacing a mold portion to press the lead portion against the stopper portion, and warping the lead portion to apply stress to a burr formed on the lead frame. 7. The deburring apparatus according to claim 6, wherein
The deburring device is characterized in that the stoppers are formed on both sides of the lead, and the pressing unit displaces the mold in different directions to press the leads against the stoppers. 8. The deburring apparatus according to claim 6, wherein the frame holding member is formed of a pipe material having a hollow inside, and an ejector is ejected toward the burr at the stopper portion. A deburring device having an ejection hole. 9. The deburring apparatus according to claim 8, wherein
A deburring device, wherein the ejector is ejected intermittently.