TW200423304A - Twice semi-etching processing and packaging structure for single-layer lead frame of image sensor - Google Patents

Abstract

The present invention relates to a twice semi-etching processing and packaging structure for single-layer lead frame of image sensor. The structure of the image sensor includes: a sensing chip, a single-layer lead frame, and a glass cover; the lead frame is done with the upper and lower twice semi-etching processing to produce the 3D structure of the die pad and the leads. The precision can be achieved to the micrometer level of integrated circuit, so that the soldering for the signal contacts of sensing chip may have better precision matching, which can reach excellent reliability and quality for current high density and high pixels of image sensing chip packaging.

Description

200423304 V. Description of the invention (1) [Technical field to which the invention belongs] The present invention relates to the engraving process and packaging structure of an image sensor, especially a kind of wafer holder and bow that are used for semi-etching once and for all. Way of three-dimensional structure of feet. Next two. Human semi-etching process [Prior technology] Please refer to Fig. 6 to Fig. 9 for its image transmission technology ^ ^ μ ^ (Image sensor). As shown in FIG. 6 and FIG. 9, the manufacturing method of the conventional lead frame (lead f ram) is stamped or stacked. Among them, the stamping method is to etch the flat substrate substrate and die (Etching) the die pad 7! And the positions and shapes of the leads 7 2 before punching the wafer holder 7 1 from the bottom. Let it float out of the pin 7 2 plane. On the other hand, the stamping method also directly punches the conductor flat plate, and directly punches out the three-dimensional structure of the wafer holder 7 1 and each pin 7 2. However, both of these methods require mechanical punching, and it is not easy to achieve fine dimensional accuracy. Therefore, it is not suitable for the packaging of a large number of pins in a small area in modern image sensing chips. Moreover, it is usually difficult to control the flatness of the lead 72 during the stamping process. It is usually necessary to cooperate with the lead 7 2 alignment process. For today's high-density, high-day image sensor chip packages, the strength is not captured, and it is not easy to achieve good results. quality. As shown in Fig. 7, another stack i-type manufacturing method uses two procedures to prepare the lead frame templates 8 1 and 8 2 of the upper and lower layers, respectively. The upper template 8 1 includes a wafer holder 8 3 and each pin 8 4. The lower layer The sample plate 8 2 contains only pins 8 5; after the upper and lower sample plates 8 1 and 8 2 are stacked, the bottom of the wafer holder 8 3 is recessed relative to the bottom of the bow 8 5, and the plastic package is electrically isolated from the entire package.

II Page 5 i 200423304 5. The process of description of the invention is as the second model 8 The measuring pin 8 The accuracy is better. The quality is a difficult problem. Fine-chip packaging, and the molecular level can have a more stacked manufacturing method for subsequent surfaces, twice the lead frame to increase the output, to achieve (2) 8 figure, the first 1, 8 2 4, 8 5 to make this; Moreover, the unsuccessful transfer of the Rong] The single-layer semi-etched structure of the main device of the Ming Dynasty is meter-level, and the degree of cooperation is true. The present invention avoids the control of the contact resistance and the semi-engraved packaging of the wire. Going to the other end can be described as shown in Figure 9 above. However, the stacking method involves the problem of dimensional accuracy matching up and down. For the small area and large image sensing chip package, the 5 delicate pins' Nanyi process encountered the same difficulties, and it is not easy to achieve a good two-lead frame template 8 1, The contact resistance of 8 2 is also well controlled to a uniform level, and it may have a small impact, and it is really necessary to improve it. For now, the lead frame engraving process is two and a half times. Therefore, it is completely a problem for the above two times to waive the machine. The process can also be completed by resolving the second half etch and overcoming the above-mentioned etching process. High-density, easy to achieve I insect engraving process, mechanical stamping process does not need to cooperate with the manufacturing precision speed can achieve better description of the problem and process and packaging problems. Made by, the precision of the number of contacts can be welded, and the quality of the product is well-relied on chemical processing. Therefore, the lead quality of the lead pin alignment procedure is achieved once, so as to save processing and provide a structure. Reach the integrated body can have image sensing crystal quality. The accuracy can reach the flatness, which is also the heap. And,. The other party's transit time is improved by the cost of the same machine, and at the same time, it can be a new and improved technology. The single-layer lead frame of the image sensor of the present invention

Page 6 200423304 V. Description of the invention The second and half # engraving contains: a sense has to say that the sensing chip inside the top surface of the wafer to be measured to make the first process of the pins to flatten the benefit of the subsequent plastic second to the flat bottom and each The third step is to embed and electrically attach the sensor chip to form the top surface of the sensor chip. (3) Process the chip holder chip system. Follow the steps above, such as step-like position, glue pre-step, and step-like pin isolation. And various glass and packaging structures, in which, the structural package of the image sensor, a single-layer lead frame and a glass cover plate; the lead frame and a plurality of pins, the inside of each pin surrounds the periphery of the chip holder; and is adhered to the chip The top surface of the seat is connected with gold pins to transmit electrical signals; and the glass cover is covered with the sense, the above three are packaged with plastic material as a whole, and the main part is: the top surface of the conductor substrate The substrate and shape of the wafer seat are etched by semi-etching, and a number of through holes are silvered in place, and the mold is fixed. The bottom surface of the conductor substrate is etched into the concave junction at the bottom of the inside of the wafer seat by semi-etching. The lead frame that has been etched in the second step of the plastic pre-mold is plated and embedded in the plastic pre-mold. The plastic pre-mold is in the wafer holder. Finally, the sensing chip is glued on the top surface of the wafer holder. Welding wires between the top surfaces of the pins, and then covering the sensing chip with a plastic pre-molded convex wall cover to complete the packaging process. The above and other objects and advantages of the present invention are not difficult to choose from the following. The detailed descriptions of the embodiments and the accompanying drawings have gained in-depth understanding.

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Page 7 200423304 V. Description of the invention (4) Of course, the present invention allows some differences in the arrangement of other parts, or the arrangement of other parts, but the selected embodiment is explained in detail in this specification. The structure is shown in the drawings. [Embodiment] Please refer to FIG. 1 to FIG. 5 for illustration, which is the selected embodiment of the present invention. This is for illustration purpose only, and it is not limited by this structure in patent application.

The invention relates to a second-layer half-etching process and packaging structure of a single-layer lead frame of an image sensor. As shown in FIG. 5, the structure of the image sensor includes: a sensing chip 1, and a single-layer lead frame. 2 与 1 Glass cover 4. The lead frame has a chip holder 2 1 and a plurality of pins 2 2, and each pin 2 2 surrounds the periphery of the chip holder 2 1 and is commonly called an inner pin 2 2 1, which is used to connect the signal contacts of the sensing chip 1; Each pin 2 2 extends outside the package body and is commonly called an outer pin 2 2 2, which is used to solder the SMT pins of an external printed circuit board to facilitate the transmission of electrical signals. The sensing chip 1 is adhered to the top surface of the chip holder 2 1 and is connected to the top surface of each inner pin 2 2 1 with a gold wire 1 1, and each signal contact of the sensing chip 1 is connected to an external signal pin. The communication between the sensor chip 1 and the outside world.

The glass cover 4 covers the sensing chip 1 to protect the sensing chip 1 and facilitates light to penetrate to the sensing chip 1. The above three are packaged with plastic material as a whole. The main production process is as follows: First step:

Page 8 200423304 V. Description of the invention (5) As shown in Figure 1, the positions and shapes of the wafer holder 21 and the pins 22 are etched on the top surface of the flat conductor substrate by half etching, and A plurality of through holes 2 3 and anchor holes 24 are etched in place. Among them, in the process of injection of the through hole 2 3 in the subsequent plastic pre-mold 3, a plurality of bumps 3 1 will be formed on the top surface of the wafer holder 21 to control the horizontal angle when the sensing wafer 1 is stuck to the wafer holder 21 to prevent The tilt of the sensing chip 1 affects the quality of subsequent bonding wires. On the other hand, it also strengthens the bonding of the plastic pre-mold 3 and the chip holder 21. The anchor holes 2 4 located at the positions of the pins 22 and 22 will be used as the basis for fixing the plastic pre-mold 3 to the lead frame 2 during the injection of the plastic pre-mold 3 to strengthen the bonding of the plastic pre-mold 3 and the pins 22. Increase the reliability quality of the overall package. Second step: As shown in Figure 2, the bottom surface of the flat conductor substrate is etched on the bottom of the wafer holder 2 1 and the bottom of each inner pin 2 2 by semi-etching. The recessed structure 2 5, the inlay and electrical isolation of the 俾 利 preform 3 are isolated. After two half-etching processes, as shown in Figs. 2 and 4, the three-dimensional structure of the entire lead frame 2 has been formed. Third step: As shown in FIG. 3, the lead frame 2 that has been etched in the first and second steps is electroplated; and as shown in FIG. 5, the lead frame 2 is embedded in the plastic pre-mold 3 by injection. And the plastic pre-mold 3 forms a convex wall 3 2 around the wafer holder 21. Finally, the silver chip 1 is used to bond the sensing chip 1 to the top surface of the wafer holder 21, and a gold wire 1 1 is welded between the sensing chip 1 and the top surface of each inner pin 2 2 1 to facilitate the transmission of electrical signals. Convex to the plastic preform 3

— 丨 一 — V. Description of the invention (6) Wall. 3 2 The top surface has been glued:: Complete the packaging process to break the cover 3, and cover the sensor crystal, as shown above, The present invention can provide the mechanical stamping process of the conventional lead frame = ,,, and Q structure. Because the lead frame 2 = the second half-etching process of the V wire frame and the garment, the precision can reach the integrated structure. Welding of the f1 signal contact made by two half-etching is possible. Crystal: f, high-pixel image sensing: The accuracy is equipped with ♦, which can achieve good trust quality for today's high-easy. Dressing is really the best choice. Rather, the invention twice enriches your molecular and molecular grades, while avoiding only = process chemical processing. The accuracy can reach a better degree. 22 of the flat, also for the stacking method to connect _ 70 Wang does not match the lead 2 2 lead program. Moreover, the production accuracy can be completely completed on the same machine in the middle of the transportation process, free of man-hours; pressure: cost, and at the same time can save a new and improved technology. The disclosure of the above-mentioned examples of the limiting example I Γ is used to explain the present invention, and is not used to = the present invention, so that any change in numerical values or replacement of equivalent components should still be within the scope of the present invention. From the above detailed description, those skilled in the art can understand that the present invention can achieve the aforementioned purpose, and it has indeed complied with the provisions of the Patent Law. Page 10 200423304 Brief description of the drawings [Simplified description of the drawings] Figure 1 is a side view of the semi-etched top surface of the conductive substrate of the present invention. Figure 2 is a side view of the semi-etched bottom surface of the conductive substrate of the present invention. Schematic diagram of the plating of the lead frame of the invention. Figure 4 is the top view of the lead frame of the present invention after the etching is completed. Figure 5 is the completion of the sensing chip packaging of the present invention. Figure 6 is the packaging completed by the conventional stamping lead frame. Figure 7 is the conventional stacked lead. Side view of the frame. Figure 8 shows the plastic pre-moulded inlay of the conventional stacked lead frame. Figure 9 shows the package completed drawing of the conventional stacked lead frame. [Illustration of drawing number] (conventional part)

Page 11 Chip holder 7 1 Pin 7 2 Sample 8 1% 8 2 Chip holder 8 3 Pin 8 4, 8 (Part of the invention) Sensing wafer 1 Gold wire 1 1 Lead frame 2 Chip holder 2 1 Pin 2 2 Inner pin 2 2 1 Outer pin 2 2 2 Through hole 2 3 、 2 4 Recessed structure 2 5 Plastic pre-mold 3 Convex grain 3 1 Convex wall 3 2 Glass cover plate 4

Claims (1)

200423304 VI. Application Patent Scope 1 · A single layer lead frame secondary semi-etching (E t ch i ng) process and packaging structure of an image sensor, the structure of the image sensor includes: a sensing chip, a single Layer lead frame and a glass cover; the lead frame has a chip holder and a plurality of pins, and the inside of each pin surrounds the periphery of the chip holder; the sensing chip is adhered to the top surface of the chip holder and connected to each lead with gold wires The top surface of the inner side of the foot is used to transmit electrical signals; and the glass cover is covered above the sensing chip. The above three are packaged with plastic material as a whole. The main manufacturing process is as follows: First step: in the flat shape The top surface of the conductive substrate is etched to the position and shape of the wafer holder and each pin by a half-etching method, and a number of through holes are etched at an appropriate position. The second step is to etch the bottom surface of the flat-shaped conductive substrate by a half-etching method. A recessed structure is etched at the bottom of the chip holder and the inner bottom of each pin, and the plastic pre-mold is embedded and electrically isolated. The third step: the lead frame that has been etched in the first and second steps is plated. The plastic pre-mold is embedded in a plastic pre-mold by injection. The plastic pre-mold forms a convex wall around the wafer holder. Finally, the sensor chip is glued on the top surface of the wafer holder, and the sensor chip and the inner sides of the pins Welding wires between the surfaces, and then pasting the glass cover on the top surface of the convex wall of the plastic pre-mold to cover the sensor chip to complete the packaging process. 2 · Single-layer lead frame for image sensor as described in item 1 of the scope of patent application Page 12 200423304 VI. Patent application scope Second half-etching process and packaging structure, in which the through holes located at the wafer base are ejected from the plastic pre-mold, a number of bumps will be formed on the top surface of the wafer base, Control the horizontal angle of the sensor chip to prevent the sensor chip from tilting and affect the quality of the bonding wire. 3 · According to the single-layer lead frame of the image sensor described in item 1 of the scope of the patent application, the second and half-I engraving process and packaging structure, in which the through holes at the positions of the pins are ejected in the plastic pre-mold It will be used as the basis for fixing the plastic pre-mold to the lead frame, strengthen the bonding of the plastic pre-mold to each pin, and increase the reliability quality of the package. Page 13