Processing method of lead frame with inner extending pins

Abstract

The present invention provides a processing method of a lead frame with inwardly extending pins, and relates to the technical field of lead frame processing. The method comprises the following steps: first, a layer of dry film is applied to the front and back of a copper material respectively; second, a part of the dry film on the front and back of the copper material is irradiated respectively to form a corresponding front polymerized anti-corrosion dry film and a back polymerized anti-corrosion dry film; third, the unexposed dry film on the front and back of the copper material is washed off to reveal the front polymerized anti-corrosion dry film and the back polymerized anti-corrosion dry film; and fourth, the front and back of the copper material are respectively etched by spraying etching liquid with etching liquid to form a plurality of inwardly extending pins located on the inner side of the front of the copper material. The present invention solves the problem that the lead frame with inwardly extending pins is processed by traditional processes in the prior art, which results in the defects of weak pin strength and poor supporting force of the inwardly extending pins, and may cause abnormal welding wires during packaging of the lead frame, which will eventually affect the production efficiency and product yield of the lead frame.

Description

Technical Field

[0001] The invention relates to the technical field of lead frame processing, in particular to a processing method of a lead frame with inwardly extending pins. Background Art

[0002] The cantilever lead of the lead frame is an important component that connects the IC chip to the external circuit. It extends inward from the main body of the lead frame, passes through the packaging material, and finally reaches the IC chip. With the development trend of miniaturization and integration of electronic components, the market has put forward requirements for the cantilever lead of the lead frame with high density and small gap.

[0003] However, in the existing technology of this industry, traditional processes are usually used to process lead frames with extended pins, which specifically include the steps of lamination, exposure, development, and etching, wherein: during lamination, a layer of dry film is applied to both the front and back sides of the copper material; during exposure, since most of the extended pins only function through the front structure, usually only part of the dry film on the front side of the copper material is irradiated for polymerization; during development, the unexposed dry film is washed away, and the polymerized dry film formed by exposure is exposed on the copper surface; during etching, the front and back sides of the copper material are sprayed with etching liquid for etching, and the polymerized dry film on the front side of the copper material can shield part of the copper material due to its anti-corrosion properties, but there is no polymerized dry film on the back side of the copper material to play an anti-corrosion role, so the etching amount and etching rate on the front and back sides of the copper material are quite different, making it difficult to control the formation process and results of the extended pins.

[0004] When the lead frame is processed by the above-mentioned traditional process, in order to meet the requirements of high density and small gap of the inner extending pins, the inner extending pins will be narrow and thin, and the half-etched plane will be uneven; the inner extending pins with a narrow and thin shape have the problems of weak pin strength and poor supporting force, and the uneven half-etched plane may cause the half-etched plane to be inconsistent with the plane of the packaging wire bonding fixture, which will cause abnormal wire bonding of the lead frame during packaging; therefore, the inner extending pins processed by the traditional process will affect the production efficiency and product yield of the lead frame.

[0005] In summary, the present invention provides a method for processing a lead frame with inwardly extending pins. Summary of the invention

[0006] The object of the present invention is to provide a method for processing a lead frame with inwardly extending pins to solve the following technical problems mentioned in the above background technology: In the prior art, the lead frame with inwardly extending pins is processed by traditional processes, which will cause the inwardly extending pins to have defects such as weak pin strength and poor supporting force, and may cause abnormal welding wires during packaging of the lead frame, which will ultimately affect the production efficiency and product yield of the lead frame.

[0007] The present invention is achieved by adopting the following technical solutions:

[0008] A method for processing a lead frame with inwardly extending pins comprises the following steps:

[0009] Step 1: Laminating: Apply a layer of dry film on the front and back of the copper material respectively;

[0010] Step 2: Exposure; respectively irradiate the partial dry film on the front side of the copper material and the back side of the copper material to form the corresponding front side polymerized anti-etching dry film and back side polymerized anti-etching dry film;

[0011] Step 3: Development; washing away the unexposed dry film on the front and back sides of the copper material to reveal the front polymerized anti-etching dry film and the back polymerized anti-etching dry film;

[0012] Step 4: Etching: Spray etching liquid on the front and back of the copper material to etch, so as to form a plurality of inner extending pins located on the inner side of the front of the copper material.

[0013] In the processing method, during exposure, not only the front side of the copper material is polymerized, but polymerized anti-etching dry films are formed on the front side and the back side of the copper material respectively; based on this, during etching, both the front side polymerized anti-etching dry film and the back side polymerized anti-etching dry film can play an anti-etching role, thereby making it possible to effectively control the etching amount and etching rate of the front side and the back side of the copper material, and then control the etching depth and the morphology of the resulting inner extending pin, so as to obtain the desired flatness of the half-etched plane and the width and height of the inner extending pin.

[0014] Furthermore, in the step 2, the front polymerized anti-etching dry film includes a plurality of unconnected front protection units, and a front protection gap is formed between every two front protection units; the back polymerized anti-etching dry film includes a plurality of unconnected back protection units, and a back protection gap is formed between every two back protection units; the plurality of front protection units and the plurality of back protection units are staggered relative to each other, and there are both a back protection unit and a back protection gap directly below each front protection unit.

[0015] In the above scheme, the front protection unit is used to shield part of the copper material from being sprayed by the etching liquid, and the shielded part forms an inner pin later; the back protection unit is used to prevent the etching liquid from being sprayed on the back of the copper material where it is located, so as to adjust the etching amount and etching rate of the back of the copper material; the front protection gap and the back protection gap are used to allow the etching liquid to be sprayed into the copper material to play an etching role. Among them, by setting the back protection unit and the back protection gap directly below each front protection unit, the etching liquid can still be sprayed from the back of the copper material into the inner pin inside the copper material while playing the role of back anti-corrosion, and then etching away the excess copper material under the inner pin, and the morphology of the bottom of the inner pin (that is, the part relatively far away from the front protection unit) can be adjusted by playing the etching role; on the contrary, if there is only a back protection unit directly below the front protection unit, and there is no back protection gap, the front protection unit and the back protection unit can form two-side protection for the copper material between the two, which will make it impossible to flexibly adjust the etching depth, and thus unable to control the height of the inner pin, which does not meet the processing requirements.

[0016] Furthermore, in the step 2, the morphology of the inner extending pin formed by etching is controlled by controlling the lengths of a plurality of front protection units, a plurality of front protection gaps, a plurality of back protection units and a plurality of back protection gaps.

[0017] In the above scheme, by controlling the length of several front protection units, the length of the top surface of several inner extending pins (i.e., the surface just below the front protection unit) can be controlled; by controlling the length of several front protection gaps, the length of the interval between every two inner extending pins among several inner extending pins can be controlled; by controlling the length of several back protection units and several back protection gaps, the area where the etching liquid is sprayed onto the back of the copper material, the etching amount and the etching rate can be controlled, and then the morphology of the bottom of the inner extending pin can be regulated.

[0018] Furthermore, in the step 4, the etching depth is controlled by adjusting the spraying pressure when the etching solution is sprayed on the front side and the back side of the copper material respectively.

[0019] Furthermore, the lengths of the plurality of front protection units are consistent, and the lengths of the plurality of front protection gaps are consistent.

[0020] In the above scheme, by setting the lengths of several front protection units to be consistent, the lengths of the top surfaces of several inwardly extending pins are made consistent; by setting the lengths of several front protection gaps to be consistent, the lengths of the intervals between every two inwardly extending pins among several inwardly extending pins are made consistent, that is, several inwardly extending pins are evenly arranged.

[0021] Furthermore, several of the back protection units have the same length, and several of the back protection gaps are divided into several back protection gaps I and several back protection gaps II according to two lengths; several back protection units are divided into a protection unit group in pairs, and there is a back protection gap II between every two protection unit groups, and there is a back protection gap I between two back protection units in each protection unit group.

[0022] In the above scheme, by setting the lengths of several back protection units to be consistent, dividing several back protection units into a protection unit group in pairs, and dividing back protection gap I and back protection gap II, uniform back side corrosion resistance can be achieved.

[0023] Furthermore, a plurality of the back protection gaps I are respectively located directly below a plurality of the front protection units, and a plurality of the back protection gaps II are respectively located directly below a plurality of the front protection gaps.

[0024] In the above scheme, the etching liquid entering from the back protection gap I can etch away the excess copper material under the inner extending pin and adjust the morphology of the bottom of the inner extending pin; the etching liquid entering from the back protection gap II can etch away the copper material located at the lower part of the area between the two inner extending pins, and the copper material located at the upper part of the area between the two inner extending pins is etched away by the etching liquid entering from the front protection gap, thereby the copper material in the area between the two inner extending pins can be completely etched away.

[0025] The beneficial effects achieved by the present invention are:

[0026] A processing method for a lead frame with an inner extending pin is provided. By forming a front polymerized anti-etching dry film and a back polymerized anti-etching dry film, when etching a copper material to form an inner extending pin, both the front polymerized anti-etching dry film and the back polymerized anti-etching dry film can play an anti-etching role, thereby effectively regulating the etching amount and etching rate on the front and back of the copper material, and further controlling the etching depth and the morphology of the resulting inner extending pin. Compared with the traditional process in which there is no polymerized dry film on the back of the copper material to play an anti-etching role, this processing method can obtain the required flatness of the half-etched plane and the width and height of the inner extending pin, so as to improve the fit between the half-etched plane and the plane of the package welding wire fixture, increase the width and height of the inner extending pin, and further improve the yield of the welding wire operation, enhance the strength and support of the pin, so as to ensure the production efficiency and product yield of the lead frame. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a schematic diagram of the changes in the structure formed in each step of the processing method described in Example 1 of the present invention;

[0028] Figure 2is a schematic diagram of the flow direction of the etching solution in step 4 of the processing method described in Example 1 of the present invention;

[0029] Figure 3 This is a 3D contour diagram of the inner extension pin obtained by the processing method described in Example 1 of the present invention after being magnified 1000 times under a Keyence VK3000 microscope;

[0030] Figure 4 This is a product morphology picture of the inner extending pin obtained by the processing method described in Example 1 of the present invention after being magnified 250 times under a tool microscope STM7;

[0031] Figure 5 It is a schematic diagram of the changes of the structure formed in each step of the processing method described in Comparative Example 1 of the present invention;

[0032] Figure 6 This is a 3D contour diagram of the inner extension pin obtained by the processing method described in Comparative Example 1 of the present invention after being magnified 1000 times under a Keyence VK3000 microscope;

[0033] Figure 7 This is a product morphology picture of the inner extending pin obtained by the processing method described in Comparative Example 1 of the present invention after being magnified 250 times under a tool microscope STM7;

[0034] Figure 8 It is a schematic diagram of the relationship between the lead etching depth and the side etching width described in Comparative Example 1 of the present invention;

[0035] Fig. 9 It is a schematic diagram of step 4 of the processing method described in Comparative Example 2 of the present invention;

[0036] Fig.10 This is a product morphology picture of the inner extending pin obtained by the processing method described in Comparative Example 2 of the present invention after being magnified under a microscope;

[0037] Fig.11 It is a schematic diagram of step 4 of the processing method described in Comparative Example 3 of the present invention;

[0038] Fig.12 This is a product morphology picture of the inner extending pin obtained by the processing method described in Comparative Example 3 of the present invention after being magnified under a microscope;

[0039] Fig.13 It is a schematic diagram of step 4 of the processing method described in Comparative Example 4 of the present invention;

[0040] Fig.14 This is a product morphology picture of the inner extending pin obtained by the processing method described in Comparative Example 4 of the present invention after being magnified under a microscope;

[0041] In the figure: 1, copper material; 2, dry film; 3, polymer dry film; 4, inner extending pin; 5, etching solution; 6, front polymer anti-etching dry film; 7, back polymer anti-etching dry film; 61, front protection unit; 62, front protection gap; 71, back protection unit; 72, back protection gap I; 73, back protection gap II; D1, back etching depth; D2, pin etching depth; W, side etching width. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0043] Example 1

[0044] This embodiment provides a method for processing a lead frame with an inner extending pin. Figure 1 and Figure 2 , including the following steps:

[0045] Step 1: Laminating: A layer of dry film 2 is respectively applied to the front and back of the copper material 1 by hot pressing;

[0046] Step 2: Exposure; through the mold pattern masking, ultraviolet rays are used to irradiate the front and back portions of the dry film 2 of the copper material 1 to form corresponding front polymerized anti-etching dry film 6 and back polymerized anti-etching dry film 7;

[0047] Step 3: Development; washing away the unexposed dry film 2 on the front and back sides of the copper material 1, revealing the front polymerized anti-etching dry film 6 and the back polymerized anti-etching dry film 7;

[0048] Step 4: Etching; spray the etching liquid 5 on the front and back sides of the copper material 1 to etch, so as to form a plurality of inner extending pins 4 located on the inner side of the front side of the copper material 1.

[0049] in:

[0050] The front polymerized anti-etching dry film 6 includes a plurality of unconnected front protection units 61, and a front protection gap 62 is formed between every two front protection units 61; the back polymerized anti-etching dry film 7 includes a plurality of unconnected back protection units 71, and a back protection gap is formed between every two back protection units 71; the plurality of front protection units 61 and the plurality of back protection units 71 are staggered relative to each other, and there are both a back protection unit 71 and a back protection gap directly below each front protection unit 61.

[0051] In step 2, by controlling the lengths of the plurality of front protection units 61, the plurality of front protection gaps 62, the plurality of back protection units 71 and the plurality of back protection gaps, the morphology of the inner extension pin 4 formed by etching can be controlled. In step 4, by adjusting the spray pressure when the etching liquid 5 is sprayed on the front and back of the copper material 1, the etching depth can be controlled.

[0052] In this embodiment: the lengths of the plurality of front protection units 61 are consistent, and the lengths of the plurality of front protection gaps 62 are consistent. The lengths of the plurality of back protection units 71 are consistent, and the plurality of back protection gaps are divided into a plurality of back protection gaps I 72 and a plurality of back protection gaps II 73 according to two lengths; the plurality of back protection units 71 are divided into a protection unit group in pairs, and there is a back protection gap II 73 between each two protection unit groups, and there is a back protection gap I 72 between the two back protection units 71 in each protection unit group. The lengths of the back protection gap I 72 and the front protection gap 62 are both shorter than the length of the back protection gap II 73, and the plurality of back protection gaps I 72 are respectively located directly below the plurality of front protection units 61, and the plurality of back protection gaps II 73 are respectively located directly below the plurality of front protection gaps 62.

[0053] In actual application, the spray pressure value and the length value of each protection unit and protection gap are specifically set according to the drawings and pin specifications required by the customer. In this embodiment, the various processing parameters used are as shown in the following table:

[0054] Table 1 Processing parameters of Example 1

[0055]

[0056] When the thickness of the copper material 1 is different, the lengths of the front protection unit 61, the front protection gap 62, the back protection unit 71 and the back protection gap all need to change accordingly, and the etching depth will also change accordingly. For example: when the thickness of the copper material 1 is 0.152mm, the length of the front protection unit 61 is 220um, the length of the front protection gap 62 is 20um, the length of the back protection unit 71 is 80um, the length of the back protection gap I 72 is 30um, the length of the back protection gap II 73 is 60um, and the etching depth is 75um.

[0057] In the processing method provided in this embodiment, during exposure, not only the front side of the copper material 1 is polymerized, but a front polymerized anti-etching dry film 6 and a back polymerized anti-etching dry film 7 are formed on the front side of the copper material 1 and the back side of the copper material 1, respectively; based on this, during etching, the front polymerized anti-etching dry film 6 and the back polymerized anti-etching dry film 7 can both play an anti-etching role. For details, please refer to Figure 2The front protection unit 61 is used to shield part of the copper material 1 from being sprayed by the etching liquid 5, and the shielded part will form the inner extension pin 4 later. The back protection unit 71 is used to prevent the etching liquid 5 from being sprayed on the back of the copper material 1 where it is located, so as to adjust the etching amount and etching rate of the back of the copper material 1. The etching liquid 5 sprayed on the front of the copper material 1 enters from the front protection gap 62, and the etching liquid 5 is directly etched and lateral etched (see Figure 2 The arrows and curves shown in the figure are used to etch away the copper material 1 located at the upper part of the area between the two inner extension pins 4. The etching liquid 5 sprayed on the back of the copper material 1 enters from the back protection gap I 72 and the back protection gap II 73 respectively. The etching liquid 5 entering from the back protection gap I 72 can be directly etched and lateral etched (see Figure 2 The excess copper material 1 below the inner extension pin 4 is etched away, and the morphology of the bottom of the inner extension pin 4 is adjusted by etching; the etching liquid 5 entering from the back protection gap II 73 can be directly etched and lateral etched (see Figure 2 The copper material 1 at the bottom of the region between the two inner protruding pins 4 is etched away (as shown by the arrows and curves in FIG. 1 ); therefore, the etching liquid 5 entering the copper material 1 from different gaps can jointly etch away the excess copper material 1 outside the inner protruding pins 4 .

[0058] Through the above processing method, the 3D contour image of the inner extension pin 4 obtained under the Keyence VK3000 microscope after magnification 1000 times and the product morphology image after magnification 250 times under the tool microscope STM7 are shown as follows: Figure 3 and Figure 4 shown.

[0059] Comparative Example 1

[0060] This comparative example provides a method for processing a lead frame with an inner extending pin. The processing method adopts a traditional process. Please refer to Figure 5 , specifically including the following steps:

[0061] Step 1: Laminating: a layer of dry film 2 is applied to the front and back of the copper material 1 by hot pressing;

[0062] Step 2: Exposure, through the masking of the mold pattern, using ultraviolet light to irradiate part of the dry film 2 on the front side of the copper material 1 for polymerization;

[0063] Step 3: Developing, washing away the unexposed dry film 2, and revealing the polymerized dry film 3 formed by exposure on the front side of the copper material 1;

[0064] Step 4: Etching: Spray the etching liquid 5 on both the front and back sides of the copper material 1 for etching. The polymerized dry film 3 on the front side of the copper material 1 can shield part of the copper material 1 due to its anti-corrosion property.

[0065] In this embodiment, the pressure of the etching liquid 5 sprayed on the front of the copper material 1 is 40 PSI, and the pressure of the etching liquid 5 sprayed on the back of the copper material 1 is 20 PSI. The length of each protection unit in the polymerized dry film 3 is 230um, and the gap between each two protection units is 20um. Among them, the spray pressure on the front of the copper material 1 is greater than the spray pressure on the back of the copper material 1. The reason is: please refer to Figure 8 By increasing the spraying pressure on the front side of the copper material 1, the pin etching depth D2 can be guaranteed to reach the required value as much as possible; however, the pin etching depth D2 is proportional to the side etching width W, and the side etching width W affects the width of the inner extending pin 4; therefore, with the pressure of the spraying pressure on the front side of the copper material 1, even if the pin etching depth D2 reaches the required value as much as possible, the side etching width W will also increase, and finally the width of the inner extending pin 4 becomes narrower.

[0066] Through the above processing method, the 3D contour image of the inner extension pin 4 obtained under the Keyence VK3000 microscope after magnification 1000 times and the product morphology image after magnification 250 times under the tool microscope STM7 are shown as follows: Figure 6 and Figure 7 shown.

[0067] Comparative Example 2

[0068] This comparative example provides a processing method for a lead frame with an inwardly extending pin. The basic steps are consistent with the four steps described in Example 1 and will not be repeated here. In the processing method provided in this comparative example, a back protection gap I72 with a length that is too small (the specific value varies according to actual conditions) is used. The back protection gap I72 with a length that is too small will result in insufficient amount of etching liquid 5, which will in turn result in insufficient copper replacement and excessive residual copper. Please refer to Fig. 9 and Fig.10 , the back protection gap Ⅰ72 with too small a length will eventually cause the pin width to exceed the upper limit, resulting in serious pin connection abnormalities.

[0069] Comparative Example 3

[0070] This comparative example provides a processing method for a lead frame with an inwardly extending pin. The basic steps are consistent with the four steps described in Example 1 and will not be repeated here. In the processing method provided in this comparative example, a back protection unit 71 with an excessively large length (the specific value varies according to actual conditions) is used. The back protection unit 71 with an excessively large length will result in insufficient side etching of the etching liquid 5, which will in turn result in copper residue in the protection covering area; please refer to Fig.11 and Fig.12 The back protection unit 71 with too large a length will eventually cause the half-eclipse plane to bulge, thereby causing the half-eclipse flatness to fail to meet the standard.

[0071] Comparative Example 4

[0072] This comparative example provides a method for processing a lead frame with an inwardly extending pin. The basic steps are consistent with the four steps described in Example 1 and are not described in detail here. In the processing method provided in this comparative example, a back protection gap I72 with a length that is too large (the specific value varies according to actual conditions) (or a back protection unit 71 with a length that is too small) is used. The back protection gap I72 with a length that is too large will cause the anti-corrosion shielding to fail; please refer to Fig.13 and Fig.14 The back protection gap I72 with too large a length will eventually cause the etching solution 5 to excessively replace the copper material 1, and the back polymerized anti-etching dry film 7 will fail to achieve the expected effect.

[0073] By comparing Example 1 with Comparative Example 1, it can be seen that: by forming a back polymerized anti-etching dry film 7 as a protective design, the amount of etching liquid 5 entering from the back of the copper material 1 can be reduced; and then the pressure of the etching liquid 5 sprayed on the back of the copper material 1 can be appropriately increased, so that the etching liquid 5 entering from the back of the copper material 1 can accurately etch away the residual copper at the bottom of the copper material 1 through direct etching and side etching; so the pressure of the etching liquid 5 sprayed on the front of the copper material 1 can be appropriately reduced, thereby ensuring the width of the inner extension pin 4. In addition, by controlling the length of each protection unit and the protection gap, the morphology of the inner extension pin 4 can be flexibly controlled so that the half-etched plane reaches the required flatness. Therefore, compared with the traditional process in which the back of the copper material 1 cannot play an anti-etching role, the processing method provided in Example 1 can improve the fit between the half-etched plane and the plane of the package welding wire fixture, increase the width and height of the inner extension pin 4, and then improve the yield of the welding wire operation, enhance the strength and support of the pin, so as to ensure the production efficiency and product yield of the lead frame.

[0074] By comparing Example 1 with Comparative Examples 2, 3, and 4, it can be seen that in practical applications, it is necessary to pay attention to controlling the length of each protection unit and the protection gap, which cannot be too large or too small, otherwise negative effects will occur.

[0075] It should be noted that the parts that are not described in detail or in detail in the above scheme, such as other basic steps such as cleaning required for processing the lead frame, and how to specifically adjust the spray pressure and the length of the protection unit, are all prior art and do not belong to the improvements made by the present invention over the prior art, nor do they belong to the scope of protection of the technical scheme of the present invention. Therefore, they will not be repeated in this article.

[0076] Of course, the above contents are only preferred embodiments of the present invention and cannot be considered to limit the scope of the embodiments of the present invention. The present invention is not limited to the above examples, and equal changes and improvements made by ordinary technicians in the technical field within the essential scope of the present invention should all fall within the scope of the patent coverage of the present invention.

Claims

1. A method for processing a lead frame having an inwardly extending pin, characterized in that: The steps include: Step 1: Laminating; a layer of dry film (2) is applied to the front side of the copper material (1) and the back side of the copper material (1); Step 2: Exposure; respectively irradiating the front side of the copper material (1) and the part of the dry film (2) on the back side of the copper material (1) to form a corresponding front side polymerized anti-etching dry film (6) and a back side polymerized anti-etching dry film (7); Step 3: Development; washing away the unexposed dry film (2) on the front side of the copper material (1) and the back side of the copper material (1), revealing the front side polymerized anti-etching dry film (6) and the back side polymerized anti-etching dry film (7); Step 4: etching; spraying etching liquid (5) on the front side and the back side of the copper material (1) respectively to etch, so as to form a plurality of inner extending pins (4) located on the inner side of the front side of the copper material (1); In the step 2, the front polymerized anti-etching dry film (6) comprises a plurality of unconnected front protection units (61), and a front protection gap (62) is formed between every two front protection units (61); the back polymerized anti-etching dry film (7) comprises a plurality of unconnected back protection units (71), and a back protection gap is formed between every two back protection units (71); the plurality of front protection units (61) and the plurality of back protection units (71) are staggered relative to each other, and a back protection unit (71) and a back protection gap exist simultaneously directly below each front protection unit (61); The lengths of the plurality of front protection units (61) are consistent, and the lengths of the plurality of front protection gaps (62) are consistent; the lengths of the plurality of back protection units (71) are consistent, and the plurality of back protection gaps are divided into a plurality of back protection gaps I (72) and a plurality of back protection gaps II (73) according to two lengths; the plurality of back protection units (71) are divided into a protection unit group in pairs, and a back protection gap II (73) is formed between each two protection unit groups, and a back protection gap I (72) is formed between two back protection units (71) in each protection unit group; The plurality of back protection gaps I (72) are respectively located directly below the plurality of front protection units (61), and the plurality of back protection gaps II (73) are respectively located directly below the plurality of front protection gaps (62).

2. The method for processing a lead frame with inwardly extending pins according to claim 1, characterized in that: In the second step, the morphology of the inner extending pin (4) formed by etching is controlled by controlling the lengths of a plurality of front protection units (61), a plurality of front protection gaps (62), a plurality of back protection units (71) and a plurality of back protection gaps.

3. The method for processing a lead frame with inwardly extending pins according to claim 1 or 2, characterized in that: In the step 4, the etching depth is controlled by adjusting the spraying pressure when the etching solution (5) is sprayed on the front side of the copper material (1) and the back side of the copper material (1) respectively.

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