CN1123068C - Lead frame manufacturing method - Google Patents

Abstract

To reduce the cost of the manufacture of a lead frame as simplifying its processes, by performing its plating-layer forming process after its etching process, and by making its plating-layer peeling process omissible. Preheating a base material 21, a laminater-roll is utilized to laminate photosensitive films 22 on both the surfaces of the base material 21. Then, utilizing parallel beam exposure devices and photomasks 23, the exposures of the photosensitive films 22 laminated on the base material 21 are performed. Thereafter, exposing the etched portions of the base material 21 to the external by developing the films 22, an etching liquid is sprayed thereon to form through portions 24. Subsequently, after removing photosensitive films 22a left on the base material 21 and applying the strike platings of Ag, selective platings are applied to certain portions of the base material 21 to form plating layers 25 on the base material 21. Thereafter, post-plating processings are applied thereto, and further, after the positions for putting chips on a lead frame are prepared by usual down-set processes, a taping process for sticking on the lead frame a tape for preventing its deformation is performed.

Description

Lead frame manufacturing method

The present invention particularly can make the manufacture method of the lead frame of tiny figure continuously about lead frame.

Usually the manufacture method of lead frame is included in the optical treatment operation of printed circuit on the egative film, form the corrosion process of lead frame structure, the electroplating work procedure of on the part egative film, electroplating selectively, ready position is installed the plug-in mounting operation of chip, prevents that the band of lead frame distortion from tiing up (taping) operation.

Detailed process is, at first removes the impurity on the egative film, covering protection material on two surfaces of egative film then, and then this egative film is in order through overexposure and developing procedure, and the corrosion egative film is to form the lead frame figure.Then with predetermined circuitous pattern parcel plating, the lead frame that following dress is electroplated and strapping is produced final lead frame like this.

In the manufacture method of this traditional lead frame, each procedure all carries out in the discontinuous mode of autonomous device, and this needs a lot of times.And manual operations can produce substandard products between discontinuous operation.In order to solve the problem that classical production process is brought, in U.S. Patent No. 5,305, a kind of manufacture method of being finished the continuous lead frame of per pass operation by individual equipment is disclosed in 043.

Figure 1A-1F has illustrated traditional flow process of making lead frame continuously.At first, preliminary treatment lead frameegative film 11 carries out strike plating to improveegative film 11 and next procedure with the adhesive force between theelectrodeposited coating 12 that forms.Then, on partegative film 11, electroplate selectively to formelectrodeposited coating 12, shown in Figure 1A.

Then,photographic film 13 is laminated on two surfaces of theegative film 11 that is provided withelectrodeposited coating 12, shown in Figure 1B.Carry out exposure process withphotomask 14 then and carry out developing procedure to form photographic film figure 13a, shown in Fig. 1 c.Therefore,parcel plating layer 12 comes out, and its indication number is 15.Yet, owing to the electrodeposited coating 15 that exposes is not eroded the corrosive agent of using by following road corrosion process, so the electrodeposited coating 15 that exposes will be removed by stripping process.

Then, the corrosive agent flushing has so just been finished the circuit diagram of the lead frame shown in Fig. 1 E to form the throughhole 16 on the egative film 11.Then, remove photographic film figure 13a (Fig. 1 F), order downloads operation and band is tied up operation again.

Yet the method for traditional continuous manufacturing lead frame has following problems.

The first, electrodeposited coating is prior to forming before other layers, and when playing photographic film lamination operation, the adhesive force between electrodeposited coating and the photographic film has just weakened like this.Also have, because random scatters in the exposure process is difficult to make the fine line circuitry figure.

The second, need a series of stripping processs to remove the part that is not corroded on the electrodeposited coating.

The 3rd, the whole technological requirement time of said method long (at least 24 hours), so efficient is not high and manufacturing cost increases.

In order to address the above problem, to the purpose of this invention is to provide a kind of continuous manufacturing and have the method for the lead frame of fine line circuitry figure.

For realizing this purpose, a kind of method of making lead frame is provided here, the operation that comprises has: (a) preheating egative film and at two backsheet surface upper strata pressure sensitivity ray films; (b) expose and the egative film of the lamination of developing to form the photographic film figure; (c) structure that forms in the corrosion process (b) is to make the lead frame figure; (d) remove the photographic film figure; (e) structure that forms in the operation (d) is electroplated selectively to form electrodeposited coating; (f) in operation (e) on the formed structure order download and band is tied up operation.

Egative film preferably by suitable made of electroplating, preferably has iron nickel (Fe-Ni) alloy or copper (Cu) alloy.In addition, preferred photographic film is that thickness is the wafer of 1～100 μ m.

In addition, be preferably in 30～80 ℃ of following preheatings and at 80～140 ℃ at operation (a) mediella, 1～6kgf/m²Pressing photographic film under the pressure.

Etching process in the operation (c) preferably adopts injection method to carry out.Here corrosive agent is preferably in 0.5～6.0kgf/cm²Pressure sprays down.

In addition, the manufacture method of lead frame of the present invention can further include in operation (d) and the pre-electroplating work procedure (e), as uses the alkaline solution degrease, pickling, or strike plating (strikeplating)

By being described in detail with reference to the attached drawings preferred embodiment, above-mentioned purpose of the present invention and advantage will be clearer, wherein:

Figure 1A is the quick-reading flow sheets that the explanation conventional method is made lead frame continuously to 1F; And

Fig. 2 A is the quick-reading flow sheets that explanation the method according to this invention is made lead frame continuously to 2D.

In lead frame manufacturing method of the present invention, any material that can electroplate also can be used as egative film, preferably has, and width is 1～20 inch iron nickel (Fe-Ni) alloy or copper (Cu) alloy.Preferred also have, and the thickness that is used as photographic film is the wafer of 1～100 μ m.Use under the situation of wafer, jet etching agent under high pressure in corrosion process, thereby form the fine pitches circuit patterns.Therefore, semiconductor equipment can be highly integrated miniature.

Provide better adhesive force between egative film and the photographic film at preliminary treatment egative film before the photographic film lamination.Be to realize this purpose, egative film carries out Chemical Pretreatment, as with alkaline electrolyte degrease and microetch, and/or the mechanical pretreatment of handling as brushing.

Then, use the lamination cylinder photographic film to be hot-pressed onto on two surfaces of egative film and carry out photographic film lamination operation.Here, the lamination operation depends on the preheat temperature of egative film, the pressure and temperature of cylinder.The lamination operation is preferably under the following condition carries out: drum pressure is 1～6kgf/cm², bowl temperature is 80～140 ℃, the preheat temperature of egative film is 30～80 ℃.

Then, in exposure and developing procedure, lamination has the egative film of photographic film to be exposed under the directional light, is exposed to dispersed light following time at egative film, because the capacity of decomposition of inherence is difficult to form the fine line circuitry figure.Also have, after exposure process, the part that unexposed part will be corroded with formation with developing solution dissolution.Here, the developer solution type that is based on photographic film is selected.

As mentioned above, carry out corrosion in the corrosion process, to form through hole by jet etching liquid.Here, preferred expulsion pressure is at 0.5～6.0kgf/cm²Between scope in.

Therefore then, peel off remaining photographic film, with two face exposure of lead frame.

In the next procedure that forms electrodeposited coating, predetermined part is electroplated selectively to form electrodeposited coating on the egative film.Here, the electrodeposited coating preferable material is a silver (Ag).Yet gold (Au) or other material that can electroplate also can be used as the electrodeposited coating material.Also have, in order to improve the adhesive force between egative film and the electrodeposited coating, can additionally on the lead frame of photographic film carry out pre-electroplating work procedure as with alkaline electrolyte degrease, pickling or strike plating removing.

Then, follow-up dress down and press mold operation can adopt usual way to carry out.

Fig. 2 A is the quick-reading flow sheets that explanation method of the present invention is made lead frame continuously to 2D.

Referring to Fig. 2 A, at first preliminary treatmentegative film 21 and be preheating to 50 ℃ then, is used in 6kgf/cm²Under the pressure, temperature is that 110 ℃ lamination cylinder presses thephotographic film 22 that thickness is 30 μ m on each surperficial upper strata ofegative film 21.

Then, referring to Fig. 2 B, to the exposure instrument exposure that lamination hasegative film 21 usefulness of photographic film layer only to produce directional light, developing forms the part that will corrode again.

Below, referring to Fig. 2 C, with 1.2kgf/cm²Pressure corrosive agent is ejected among Fig. 2 B on the formed structure, make through hole 24.

Subsequent, referring to Fig. 2 D, remove photographic film 22a remaining on theegative film 21, carry out silver-colored strike plating then in the above, part egative film is electroplated selectively to form electrodeposited coating 25, has therefore improved the adhesive force between time road wiring operation chips and the lead frame.Operation after electroplating again, and position by placing chip on the general following dress operation preparation lead frame.Then with tiing up operation to prevent the distortion of lead frame.

As mentioned above, make continuously in the method for lead frame in the present invention, form electrodeposited coating after corrosion process, therefore saved a series of operations of peeling electrodeposited coating off, this operation is followed the electroplating work procedure before corrosion process and is produced, and has simplified manufacturing process.The result has reduced manufacturing cost.And owing to adopt wafer as photographic film, corrosive agent can adopt high-pressure injection, forms the lead frame figure with fine pitches.In addition, reduced problem, and can carry out manufacturing process continuously in the exposure process irregular reflection.

Claims (8)

1. method of making lead frame comprises operation:

(a) preheating egative film and at each surperficial upper strata pressure sensitivity ray film of egative film; (b) egative film of exposure and development lamination is to form the photographic film figure; (c) structure that forms in the corrosion process (b) is to form the lead frame figure; (d) remove the photographic film figure; (e) formed structure in the operation (d) is electroplated selectively to form electrodeposited coating; And (f) in operation (e) on the formed structure order download and band is tied up operation.

2. the method in the claim 1, wherein photographic film is a kind of wafer.

3. the method in the claim 2, wherein wafer thickness is 1～100 μ m.

4. the method in the claim 1 wherein is preheating to 30～80 ℃ with egative film in the operation (a).

5. the method in the claim 1 is wherein used 1～6kgf/cm²The lamination cylinder of pressure and 80～140 ℃ of temperature carries out the lamination in the operation (a).

6. the method in the claim 1 is wherein carried out corrosion in the operation (c) by jet etching liquid, to form through hole.

7. the method in the claim 1, further comprise operation (d) and (e) between pre-electroplating work procedure.

8. the method in the claim 7, wherein pre-electroplating work procedure is by the alkaline electrolyte degrease, pickling or strike plating are carried out.

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