JPH09237866A - Manufacture of dam-barfree lead frame member and dam-barfree lead frame member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a dam-bar free lead frame member by which a dam bar part, in a predetermined width and a predetermined shape, composed of an insulating resin is formed easily in a predetermined position between leads by a method wherein a predetermined region on a lead frame not containing a dam bar is coated with the resin so as to bury a dam-bar formation region, the resin is hardened and the resin is irradiated with a laser beam so as to be molded. SOLUTION: A dam bar 120A is formed of an insulating resin 120, and a resin sealing operation is performed. When a dam-bar free lead frame member for a resin-sealed semiconductor device is manufactured, the outer shape of lead frames 112, 113 which do not comprise any dam bar is worked from a lead frame blank. Then, a region which corresponds to a dam bar in the resin sealing operation of the lead frames 112, 113 whose outer shape is worked is coated with the insulating resin used to form the dam bar, and at least the dam-bar formation region is buried. Then, the insulating resin 120 which is buried in the dam-bar formation region is hardened, and the hardened insulating resin 120 is then irradiated with a laser beam 140 so as to be molded.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a dambar-free lead frame member for a resin-sealed semiconductor device, in which a dambar is formed of an insulating resin and resin-sealed.
The present invention relates to a dam bar free lead frame member manufactured by the manufacturing method.

[0002]

2. Description of the Related Art Conventionally, resin-encapsulated semiconductor devices (plastic-encapsulated packages) used in electronic control devices and the like.
10 has a structure as shown in FIG. 10, and using a lead frame with a dam bar, (a) a semiconductor element such as an LSI can be simply used as a die bonding material such as silver paste on the die pad portion of the lead frame. And then electrically connecting the terminals of the semiconductor element to the lead frame by wire bonding, (b) resin-sealing the semiconductor element and the lead frame with a resin, and then resin-sealing. A step of removing resin burrs, which is the protrusion of the sealing resin at the time of stopping, by a method such as water jet or sandblasting, and (c) Furthermore, a dam bar for stopping the protrusion of the resin formed between the outer leads of the lead frame. Punching and removing with a punch, (d) After that, the outer lead part of the lead frame is processed into a predetermined shape with a mold That step, etc. have been produced through a.

A lead frame with a dam bar used for manufacturing the resin-sealed semiconductor device (plastic-sealed package) is generally the one shown in FIG. Inner lead portion 901 that is electrically connected, an outer lead portion 902 that is electrically connected to an external circuit, a die pad portion 903 on which a semiconductor element is mounted, and to stop the flow of resin during resin sealing by a mold die press. The dam bar 904 and the frame 906 required for assembling the semiconductor device. As a material of such a lead frame 900 with a dam bar, a copper alloy or a 42% nickel-iron alloy or the like is used, and the lead frame 900 with a dam bar is manufactured by a punching method using a die press or a photolithography technique. This has been performed by an etching method using a corrosive liquid.

However, the above lead frame has a structure in which a dam bar is provided when manufacturing a resin-sealed semiconductor device, and when resin sealing is performed using this, resin burr is inevitable. Further, in recent years, along with the trend of light and thin electronic devices and high integration of semiconductor elements, resin-sealed semiconductor devices are remarkably reduced in size and thickness and the number of electrode terminals is increased. Semiconductor device, especially QF
P (Quad Flat Package) and TQF
P (Thin Quad Flat Package)
In such a package with a large number of pins, the pitch of the outer leads, which are electrode terminals, has been narrowed from a pitch of 0.65 mm to a pitch of 0.5 to 0.3 mm in recent years. The narrow pitch of the outer leads has made it very difficult to remove the dam bar of the plastic sealed package. In other words, as the outer lead pitch becomes narrower, the punch for punching the dam bar must also be made thinner, which increases the manufacturing cost of the punch and the occurrence of chipping of the punch that occurs when removing the dam bar. Was causing a shorter life. For example, when cutting the outer lead dam bar having a pitch of 0.3 mm, the punch thickness needs to be as thin as about 0.1 mm, the strength of the punch becomes weak, and the manufacturing thereof is inevitably difficult. Furthermore, the protruding position of the outer lead may be displaced in the plastic package due to the influence of shrinkage of the resin, and a certain processing accuracy is required at the time of dam bar cutting, but when the pitch is narrow,
There is also a problem that the amount of deviation allowed in the dam bar cutting process becomes small, and the occurrence of defects in the dam bar removing process becomes large. As described above, various problems have arisen with the increase in the number of pins and the pitch of the package, and the method itself for removing the dam bar by the punch has become very difficult.

To cope with these problems, a method has been proposed in which a dam bar portion is formed of an organic insulating resin using a dam bar free lead frame. Here, a lead frame without a dam bar is referred to as a dam bar free lead frame, but may also be referred to as a dam barless lead frame. This method is as shown in FIG.
A metal lead frame without a dam bar is used for the outer lead 512, and a dam bar 52 made of an organic insulating resin is provided around the mold line 507 as shown in FIGS.
0 is provided. In FIG. 5A, in order to make it easy to understand the position where the insulating resin is embedded, the thin residual insulating resin layer on the outer lead and the deterioration of the outer shape are omitted.
It is shown in a simplified manner. FIG. 5B is a diagram showing a case of a lead frame with a dam bar, and is given here for easy understanding of the difference from the dam bar free lead frame shown in FIG. 5A.

Then, the dam bar portion 52 shown in FIG.
The formation of 0 has conventionally been performed in the process as shown in FIG. Simply put, paste-like insulating resin is applied to predetermined positions including the package line (molding line) of the dam bar-free lead frame, dried in a curing oven (drying oven), and then the outer leads are made with a press die. Insulating resin was embedded between them to form the dam bar portion. A sectional view of each step in the dam bar formation region is shown in FIG. 8, and the method shown in FIG. 7 will be described in more detail. 8 (b1) and FIG.
(E1) is a plan view corresponding to FIGS. 8 (b) and 8 (e). FIG. 8A shows a cross section of a lead including a package line after a dam bar-free lead frame having no dam bar is externally processed by etching or the like and a predetermined portion is plated. . 8B to 8E below also show the state of each process at this position. The insulating resin applied to the lead 702 of the lead frame by the dispenser is 720
8B, as shown in FIG. 8B, the lead 702 is not completely filled with the viscous and coated state. In this state, a drying process for removing the solvent component is performed. (FIG. 8C) After drying, the dried insulating resin 720 is pressed between the leads 702 by hot pressing using a press die (FIG. 8D), and the leads 702 are completely insulated. The resin 702 embedded between the leads 702 is cured (cured) while being filled with the resin of
The dam bar section will be used. (FIG. 8E) In this method, since the dam bar at the time of resin sealing is formed of the organic insulating resin 720, after resin sealing as in the case of using the above-mentioned lead frame with a dam bar. It does not require the step of punching the dam bar with a punch and is very effective for narrowing the outer lead pitch.

[0007]

However, as shown in FIG. 7 and FIG.
In the method of using a dambar-free lead frame having no dambar as shown in FIG. 2 and providing a dambar made of an organic insulating resin at a predetermined position between the leads, the dambar portion is 0.5
It is difficult to form the dam bar part at a predetermined position including the package line as narrow as about mm, and the surface tension due to the insulating resin paste causes deformation when it is housed between the outer leads, resulting in insulation of the dam bar part. A part of the resin is easily removed from the package line. Further, in the step of forming the dam bar with the insulating resin 720 shown in FIGS. 7 and 8, pressure is applied by a press for the purpose of filling the space between the outer leads with the insulating resin in a softened state applied by the dispenser. When the insulating resin is embedded between the leads, the insulating resin applied on the outer leads enters between the leads, so that it is difficult to form the dam bar portion in a predetermined position with a good linearity. and again,
It was also difficult to form the insulating resin thinly left on the outer leads after pressing into a predetermined shape at a predetermined position without variation between the outer leads. As described above, it is difficult to provide the dam bar portion made of the insulating resin with a predetermined width and shape at a predetermined position between the leads, and it is required to cope with the dam bar portion. Under the circumstances, the present invention provides a method of forming a dam bar made of an insulating resin by using a dam bar free lead frame having no dam bar in order to cope with a multi-pin and narrow pitch semiconductor device. It is intended to provide a method capable of solving the above problems.

[0008]

A method for manufacturing a dam bar-free lead frame member according to the present invention is a dam bar free lead for a resin-sealed semiconductor device in which a dam bar is formed of an insulating resin and resin-sealed. A method of manufacturing a frame member, which is equivalent to at least (A) a step of externally processing a lead frame having no dam bar from a lead frame material and (B) a dam bar at the time of resin-sealing the externally processed lead frame. By applying an insulative resin for forming a dambar to the area to be filled, at least filling the dambar forming area, (C) curing the insulative resin embedded in the dambar forming area, and (D)
And a molding step of molding the cured insulating resin portion by irradiating it with laser light. The viscosity of the insulating resin applied is 20000.
It is characterized by being cps or less and 8000 cps or more. Further, the laser light is a laser light such as an excimer laser or a carbon dioxide gas laser that can remove the irradiated portion by irradiating an insulating resin. Further, the above-mentioned irradiation of the insulating resin with the laser beam is characterized by masking irradiation using a mask that can be adjusted so that a predetermined amount of light hits a predetermined portion of the insulating resin. The dam bar free lead frame member of the present invention is characterized by being manufactured by the method for manufacturing a dam bar free lead frame member of the present invention. As described above, the lead frame having no dam bar is referred to as a dam bar free lead frame here, but may be referred to as a dam barless lead frame.

[0009]

In the method of manufacturing the dam bar-free lead frame member of the present invention, the dam bar portion made of an insulating resin having a predetermined width and shape is provided at a predetermined position between the leads by adopting such a structure. It makes it possible.
Specifically, a step of filling at least the dam bar forming area by applying an insulating resin for forming the dam bar to the area corresponding to the dam bar at the time of resin sealing of the outer shape processed lead frame, and the dam bar forming step. This is achieved by having a step of curing the insulative resin embedded in the region and a molding step of irradiating the cured insulative resin portion with laser light to form the resin. Specifically, in the area corresponding to the dam bar at the time of resin-molding the lead frame that has been externally processed, the viscosity is 20000 cps or less
By applying an insulating resin of 8000 cps or more, the insulating resin can be surely embedded between the leads. Then, the insulating resin embedded in the dam bar formation region is cured, and the cured insulating resin portion is molded by irradiating with KrF excimer laser light or carbon dioxide gas laser light to form a dam bar portion between the leads. Can be formed to have a predetermined width and a predetermined shape. When molding an insulating resin by laser light irradiation, the applied insulating resin is applied on the leads and between the leads by masking irradiation using a mask that can adjust the amount of light depending on the laser light irradiation position. Even if the flatness cannot be ensured, it becomes possible to make the surface almost flat by shaping the laser beam. It is preferable that the insulating resin between the leads, which are flattened in this way and serve as a dam bar, be slightly left (10 μm or less) outside the leads from the lead surface. This is because if the irradiation of the laser beam is too much, the insulating resin that becomes the dam bar is removed more than necessary, and the sealing resin leaks from the dam bar during resin sealing. As a result, resin leakage is less likely to occur during resin sealing. It is also possible to form the insulating resin that remains thinly on the outer leads in a predetermined shape (substantially rectilinear) at a predetermined position without variation between the leads, which ultimately results in the influence of the insulating resin on each outer lead. It is supposed that it is possible to prevent the coplanarity defect and the skew defect of the outer lead after the package sealing (molding) due to the variation of the above.

[0010]

EXAMPLE An example of a method for manufacturing a dam bar free lead frame of the present invention will be described with reference to the drawings. FIG.
FIG. 1A is a cross-sectional view of the dam bar formation region viewed from the outer lead side in the process of the dam bar free lead frame of the present embodiment, and FIG. 1B1, FIG. 1C1 and FIG.
(E1) are shown in FIG. 1 (b), FIG. 1 (c), and FIG.
The top view corresponding to (e) is shown. FIG.
FIG. 3A is a plan view of a dam bar free lead frame used in the method for manufacturing the dam bar free lead frame of this embodiment, and FIG. 3B is FIG.
FIG. 6 is a plan view showing a state in which an insulating resin is applied to the dam bar free lead frame shown in FIG. 1 in FIGS. 1 and 3
10 is a dam bar free lead frame, 111 is a die pad, 112 is an inner lead, 113 is an outer lead, 114 is a tab suspension lead, 116 is a frame portion, 1
20 is an insulating resin, 120A is a dam bar, 121 is a mold line, and 140 is a laser beam.

First, a dam bar-free lead frame 110 having no dam bar shown in FIG. 3A was produced by etching. (FIG. 1A) The dam bar-free lead frame having no dam bar will be briefly described with reference to FIG. 6 regarding the etching process.
First, the lead frame material 610 made of a thin plate made of a copper alloy, 42% nickel-iron alloy or the like and having a thickness of about 0.1 mm to 0.2 mm is thoroughly washed (FIG. 6 (a)), and then potassium dichromate is added. A photosensitive photoresist 620 such as a water-soluble casein resist as a photosensitizer is uniformly applied to both surfaces of the lead frame material 610 (FIG. 6 (b)), and a high pressure is applied through a mask having a predetermined pattern. After exposing with a mercury lamp and developing the photosensitive resist with a predetermined developing solution to obtain a resist pattern 630, a film hardening process, a cleaning process and the like are performed as necessary (FIG. 6 (c)), and then a second chloride The thin plate is sprayed with an etching solution containing an iron aqueous solution as a main component to etch the thin plate to a predetermined size (FIG. 6 (d)), and the resist is peeled off and washed to prepare. (FIG. 6 (e)) After that, a predetermined area is plated with silver, washed and dried,
After the step shown in FIG. 7 and the step of taping the inner lead part with a polyimide tape with an adhesive for fixing, etc., a predetermined amount of the tab suspension bar is bent as necessary to down set the die pad part.

Next, by using the dam bar-free lead frame 110 obtained by the etching process, the insulating resin 120 is applied to the dam bar forming region by a dispenser, so that the insulating resin is applied between the leads. It was completely embedded so that there were no voids (Fig. 1 (b)). An insulative resin having a predetermined thickness is formed evenly on the surface of the lead. The insulating resin has a viscosity of 15,000 cps.
Able stick thermosetting polyimide (rel
y-imide) was used. As a dispenser,
Using a ML-808i manufactured by Musashi Engineering Co., Ltd., the dam bar free lead frame obtained by external processing by etching is fixed with a predetermined jig pin, and the insulating resin application area is stored in advance. Was applied to. The required properties of the insulating resin are that the insulating resin is completely filled between the leads by application with a dispenser, and the viscosity is such that it does not spread more than necessary. Those are preferable. Such viscosity is 20000cps or less, 8000c
ps or more. The coating method is not particularly limited to coating with a dispenser, but by coating,
It is necessary that the insulating resin is completely filled between the leads and does not spread more than necessary.

Subsequently, the dam bar free lead frame, which had been applied to a predetermined area, was placed in a curing oven and cured. (FIG. 1 (c)) The curing conditions are 200 ° C. and 20 minutes.

Next, a KrF laser (248 nm) light is irradiated (FIG. 1 (d)) to form an insulating resin 12 having a predetermined shape.
0 was molded to form a dam bar 120A in which an insulating resin having a predetermined width was embedded between the leads. (FIG. 1 (e)) The width h in FIG. 1 (e) is preferably 10 μm or less in consideration of resin leakage at the time of resin sealing. Irradiation of the KrF laser light was performed as shown in FIGS.
In FIG. 4, 400 is a laser processing device, 410 is a laser beam,
Reference numeral 420 is a mask, 430 is a lens system, and 110 is a lead frame. The laser light 410 is shaped by the mask 420, reduced by the lens system 430, and applied to the workpiece. The mask used in FIGS. 4A and 4A is a mask for transmitting laser light into a predetermined shape.
A region having a shape corresponding to this is irradiated with laser on the lead frame. On the other hand, when the insulating resin is applied, the leads have a convex shape, and the flatness of the insulating resin cannot be maintained on the leads or between the leads, which causes a problem during resin sealing. In such a case, as shown in FIGS. 4A and 4B, a mask that can adjust the amount of light transmission at a pitch that matches the lead shape of the lead frame is used.
It is possible to deal with the unevenness of the flatness of the insulating resin when the insulating resin is applied to the dam bar forming region, and it is possible to secure the substantially flatness after the laser irradiation. In FIGS. 4A and 4B, T1 and T2 indicate regions having different transmittances of laser light, and the light passing through these regions of the mask 410 irradiates the surface of the lead frame 110 with corresponding light amounts. Becomes 4 (b) (a) is a plan view showing the state of the dam bar formation region when the insulating resin is applied.
4B and 4B are cross-sectional views taken along line B1-B2 of FIGS. 4 (c) and (a) are plan views showing the state of the dam bar formation region after laser processing.
4C and 4B are cross-sectional views taken along line C1-C2 of FIGS.

A KrF excimer laser was used as the laser beam, because it can be processed into a clean shape as compared with a carbon dioxide gas laser or a YAG laser. This is because the excimer laser enables photochemical processing called ablation processing for polymers such as polyimide. That is, it is possible to non-thermally separate the bond between the molecules of the substance. In recent research, even excimer lasers are thermal processes, and the reason why the removal processing surface is better than the conventional infrared lasers such as carbon dioxide lasers and YAG lasers is that ultra-short pulses and high peak output lead to material It is said that this is due to the extremely small thermal conductivity of N. Therefore, even with a carbon dioxide laser, if this is used with a short pulse and high peak output,
There is also a view that it can reduce thermal damage. Also, Y
Since the fourth harmonic of the AG laser is ultraviolet light with a wavelength of 266 nm, attention is paid to the good stability and maintainability of the YAG laser, and it is also possible to use this for fine processing of polymers such as polyimide. Being tried.

The lead frame member thus formed is subjected to plating treatment or down-set processing for shifting the die pad downward by a predetermined height, if necessary.

Next, the dam bar free lead frame member of the present invention will be described. 2A is a plan view of the dam bar free lead frame member of the embodiment, FIG. 2B is a sectional view taken along line A1-A2 of FIG.
(A) shows a state in which an insulating resin is embedded as a dam bar in the outer lead portion of the dam bar free lead frame of the second embodiment. In addition, also in FIG.
For the sake of clarity, the thin residual insulating resin layer on the outer leads is omitted and shown in a simplified manner. In FIG. 2, 1
00 is a lead frame member, 110 is a lead frame,
Reference numeral 120 denotes an insulating resin. The dam bar-free lead frame member of the present embodiment is manufactured by the method of manufacturing the lead frame member of the above embodiment, the positional accuracy of the dam bar is controlled within a range of ± 50 μm, and
The accuracy of the width of the dam bar part embedded between the leads is ± 100 μm
The linearity can be secured, the variation in each lead is small, and as a result, it is possible to sufficiently cope with the increase in the number of pins (increased number of terminals) of the semiconductor device.

Examples of the lead frame include copper alloy and 42 alloy (42% nickel-iron alloy), but the lead frame is not limited thereto. As described above, the insulating resin 120 is a resin in which the insulating resin is completely filled between the leads by application with a dispenser, and has a viscosity that does not spread more than necessary, and is thermosetting. Molds are preferred. Specifically, in addition to thermosetting polyimide, thermoplastic polyimide may be used.

[0019]

As described above, the dam-bar-free lead frame of the present invention is resin-sealed so that the outer leads of the resin-sealed semiconductor device can be further narrowed in pitch with the high integration of semiconductor elements. It is possible to provide a semiconductor device of the type. Specifically, when the dam bar-free lead frame of the present invention is used for resin encapsulation, it is formed so that the encapsulating resin (mold resin) does not have burrs in the insulating resin portion forming the dam bar. It does not require a burr removal process as in the case of using a conventional lead frame with a dam bar, and when using the conventional dam bar free lead frame manufactured by the process shown in FIGS. 7 and 8. There is no resin leakage when the resin is sealed. After all, by using the dam bar-free lead frame of the present invention to perform resin encapsulation, it is possible to manufacture a resin-encapsulated semiconductor device which is stable in quality and can cope with the increase in the number of terminals.

[Brief description of drawings]

FIG. 1 is a diagram showing steps of a method for manufacturing a dam bar free lead frame member of an example.

FIG. 2 is a schematic view showing an example dam bar free lead frame member.

FIG. 3 is a schematic diagram of a dam bar-free lead frame used in Examples.

FIG. 4 is a diagram for explaining molding by laser light irradiation.

FIG. 5 is a diagram for explaining formation of a dam bar of a dam bar free lead frame.

FIG. 6 is a diagram for explaining a manufacturing process by etching a dam bar free lead frame.

FIG. 7: Method for manufacturing conventional dam bar free lead frame member

FIG. 8 is a schematic cross-sectional view of a main part in each step in the conventional method of manufacturing a dam bar free lead frame member.

FIG. 9 is a diagram of a conventional lead frame with a dam bar.

FIG. 10 is a schematic view of a resin-sealed semiconductor device.

[Explanation of symbols]

100 Dam Bar Free Lead Frame Member 110 Dam Bar Free Lead Frame 111 Die Pad (Tab) 112 Inner Lead 113 Outer Lead 114 Tab Hanging Lead 116 Frame Part 120 Insulating Resin 120A Dam Bar 121 Mold Line (Package Line) 400 Laser Processing Equipment 410 Laser light 420 Mask 430 Lens system 512 Inner lead 513 Outer lead 514 Dam bar 507 Mold line (package line) 520 Dam bar made of insulating resin 610 Lido frame material 620 Photo resist 630 Resist pattern 640 Outer lead 700 Dam bar Free lead frame 701 Inner lead 702 Outer lead 704 Die pad 710 Dice Spencer 20 Organic Insulation Resin Part 730 Cure Furnace (Drying Furnace) 740 Press Mold 900 Lead Frame 901 Inner Lead 902 Outer Lead 903 Die Pad 1000 Semiconductor Device 1001 Semiconductor Element 1002 Die Pad Part 1003 Inner Lead Part 1004 Outer Lead Part 1005 Resin Part 1006 Semiconductor Element Terminal (pad) 1007 wire

Claims (5)

[Claims] 1. A method of manufacturing a dambar-free leadframe member for a resin-sealed semiconductor device, comprising forming a dambar with an insulating resin and sealing the resin, which comprises at least (A) a leadframe material. By the step of externally processing the lead frame having no dam bar, and (B) applying the insulating resin for forming the dam bar to the area corresponding to the dam bar at the time of resin sealing of the externally processed lead frame, At least a step of embedding the dam bar forming area, a step (C) of curing the insulating resin embedded in the dam bar forming area, and a step (D) of molding the cured insulating resin portion by irradiating laser light. A method for manufacturing a dam bar-free lead frame member, comprising: 2. A method for manufacturing a dam bar free lead frame member, wherein the applied insulating resin has a viscosity of 20000 cps or less and 8000 cps or more. 3. The laser beam according to claim 1 or 2,
A method of manufacturing a dam bar-free lead frame member, which is a laser beam such as an excimer laser or a carbon dioxide gas laser that can remove an irradiated portion by irradiating an insulating resin. 4. The irradiation of the insulating resin with laser light according to claim 1 is masking irradiation using a mask that can be adjusted so that a predetermined amount of light hits a predetermined portion of the insulating resin. A method for manufacturing a dam bar free lead frame member. 5. A dam bar free lead frame member manufactured by the method for manufacturing a dam bar free lead frame member according to any one of claims 1 to 4.