TWM618877U - Flip chip substrate and packaging structure thereof - Google Patents

Abstract

A flip chip substrate has a surface on which a plurality of groups of groove units are formed, each group of groove units includes a plurality of grooves, and the grooves of each group of groove units jointly surround the surface Form a predetermined area, the predetermined area includes a connection area, the area of the predetermined area is larger than the area of the connection area, and the grooves are arranged around the predetermined area; when the chip is flip-chip on the substrate, Make each solder ball on the wafer correspond to the common center of the grooves of each group of groove units or the center of the connection area, so that the water is easier to remove the flux around the solder balls during the cleaning process. And it can balance the fluidity of the filling material filled under the chip, reduce the formation of voids, and ensure product reliability.

Description

Flip chip substrate and its packaging structure

This creation relates to the technical field of flip-chip packaging, in particular to improve the fluidity of the filling material at the bottom of the chip to reduce the generation of voids, and to make the flux easier to be eliminated during the cleaning process.

In the flip chip packaging process of the chip, an underfill process (underfill) is required when flipping the chip onto the substrate. The filling material (generally epoxy-based liquid material) is filled under the chip by capillary action, but it is set on the chip The arrangement of different pitches between the plurality of solder balls (bump balls) below will cause the flow rate of the filling material to be uneven and lead to incomplete filling. In addition, when the size of the solder ball is less than 50um, the flux will remain around the solder ball after the chip is mounted and cannot be completely cleaned off.

Taiwan Patent No. I229928 discloses a semiconductor package structure, as shown in FIG. 1, including: a semiconductor element A, a substrate B, a number of solder bumps C, a primer D, a buffer, and a solder ball E. The substrate B is arranged under the semiconductor element A; a bonding area is formed between the first surface of the semiconductor element A and the upper surface of the substrate; a number of solder bumps C are arranged in the bonding area to electrically connect the semiconductor element A and the substrate B; The primer D is filled in the bonding area and covers the solder bumps C to tightly bond the semiconductor device A and the substrate B; the buffer part E is arranged in the bonding area to buffer and control the filling of the primer D; several soldering The ball E is arranged on the lower surface of the substrate B. Among them, in the primer filling process, the primer D flows between the semiconductor device A and the substrate B in a capillary phenomenon, and the groove B1 formed on the substrate B is used as a buffer to confirm the glue discharge condition of the primer. Accurately control the amount of glue.

However, since the I229928 patent is to form the groove B1 on the surface of the substrate B corresponding to the periphery of the semiconductor element A, that is, the solder ball E provided under the semiconductor element is located within the range of the groove B1. The pitch of the solder balls E is too small or uneven, resulting in insufficient fluidity of the primer D filled into the bottom of the semiconductor device A, resulting in voids due to incomplete filling; in addition, when the size of the solder balls is less than 50 µm, on the semiconductor device After the chip is sliced, the flux is likely to remain around the solder balls, which cannot be completely cleaned off during the cleaning process, and more processes must be added for subsequent processing.

The purpose of this creation is to improve the lack of fluidity of the filling material at the bottom of the chip during flip-chip packaging, and the lack of flux that is not easily eliminated during cleaning.

The technical feature of this creation is to provide a flip chip substrate with a surface on which a plurality of groove units are formed, each group of the groove unit includes a plurality of grooves, and each group of the groove unit has a plurality of grooves. The grooves together enclose a predetermined area on the surface, the predetermined area includes a connecting area, the area of the predetermined area is larger than the area of the connecting area, and the grooves are arranged around the predetermined area. With the structure of the substrate, when the flip chip is packaged on the substrate, each solder ball provided on the chip corresponds to the connection area between the grooves of each set of groove units. Therefore, by The groove can balance the fluidity of the filling material filled under the chip, reduce the formation of voids, and make it easier for water to remove the flux around the solder balls during the cleaning process, ensuring product reliability.

Preferably, the grooves on the substrate of the invention are also arranged around the connection area, and there is a distance between the grooves and the connection area. In this way, the distance between the groove and the connection area is provided to make the fluidity of the filling material on the substrate more balanced, and during the cleaning process, it is easier for water to enter the area around the solder ball, so that the flux is easier to be cleaned.

Preferably, the connection area on the substrate of the invention is used to connect with a plurality of solder balls of a chip. In this way, the solder balls are arranged in the area between the grooves, so that the cleaning of the substrate flux and the material filling effect are relatively good.

Preferably, each set of groove units on the substrate of the invention may include four grooves, and the four grooves are arranged around the center of the groove unit. Thereby, the fluidity of the filling material can be improved from multiple directions.

Preferably, the four grooves can be arranged at equal angles along the circumference. In this way, the full fluidity of the filling material can be improved from the front, back, left, and right directions.

Preferably, the diameter of the grooves is less than half of the distance between the solder balls. Thereby, the bonding between the solder ball and the substrate can not be affected under the premise of providing sufficient fluidity of the filling material.

This creation also provides a flip-chip package structure using the flip-chip substrate, including: a chip with a plurality of solder balls on one side; a substrate with a surface on which a plurality of groove units are formed, each A group of the groove unit includes a plurality of grooves, and the grooves of each group of the groove unit jointly enclose a predetermined area on the surface, the predetermined area includes a connecting area, and the area of the predetermined area is larger than The area of the connection area, and the grooves are arranged around the outer periphery of the predetermined area; wherein, when the chip is flip-chip on the substrate, each solder ball is connected to each group of groove units correspondingly Of the connection area.

Through the aforementioned flip-chip substrate and flip-chip package structure, this creation can improve the fluidity of the filling material at the bottom of the chip to reduce voids, and make the flux easier to be eliminated during the cleaning process, thereby ensuring product stability And reduce manufacturing costs.

The following is a more detailed description of the implementation of this creation in conjunction with the drawings and component symbols, so that those who are familiar with the art can implement it after studying this manual.

Fig. 2 is a schematic top plan view showing the structure of the flip chip substrate of the present creation; Fig. 3 is a schematic side cross-sectional view showing the structure of the flip chip substrate of the present creation.

The flip chip substrate 1 provided by the present creation has a surface 10 on which a plurality of groups of groove units 11 are formed. Each group of groove units 11 includes a plurality of grooves 111, and each group of groove units 11 includes A plurality of grooves 111 collectively enclose a predetermined area S on the surface 10 of the substrate 1. The predetermined area S includes a connection area S2 (as shown in FIG. 4), and the connection area S2 is a part of the predetermined area S Therefore, the area of the predetermined area S is larger than the area of the connection area S2, and the grooves 111 are arranged around the outer periphery of the predetermined area S, and the grooves 111 are also arranged around the connection area S2, and There is a distance between the grooves and the connection area S2.

The connection area S2 is used to contact a plurality of solder balls 21 of a chip, so that the chip is fixed to the substrate 1 through the solder balls 21. The angle between the solder balls and the substrate 1 is less than 90 degrees. When cleaning flux or When filling the material, the flux cannot be cleaned completely due to the acute angle between the solder ball and the substrate 1, and the filling material cannot fill the space with the acute angle; when the surface of the substrate 1 is cleaned with a mixture of saponifier and water When the flux is used, or when filling material is used to fill the space between the substrate 1 and the chip, the flow rate of the liquid (mixed liquid of saponification agent and water or filling material) Lowering, the liquid can slowly flow into the acute angle between the solder ball and the substrate 1, and exhaust the air in the acute angle, so that the liquid can be completely filled into the acute angle, and the surface of the substrate 1 can even be damaged through the groove 111. The surface tension of the liquid allows the liquid to flow smoothly into the gaps in the acute angle without squeezing the air into the acute angle, and when cleaning the flux on the surface of the substrate 1, the use of saponifiers can be reduced, and the surface tension of water can be destroyed. Save the cost of saponification agent.

More specifically, the predetermined area S refers to the circular area enclosed by the shortest distance L from the center S1 of each group of groove units 11 to each groove 111, so the radius of the predetermined area is L, where The circular area is, for example, a perfect circle or an ellipse; in more detail, the center S1 refers to the common center of the grooves 111 in each group of groove units 11, and the center S1 is also the center of the predetermined area. The die solder balls 21 are adhered to a predetermined area of the substrate 1, and the contact surface of the solder balls 21 and the substrate 1 is the connection area S2.

As shown in Fig. 2, the present invention preferably forms the groove unit 11 with four grooves 111 on the surface 10 of the substrate 1, and the four grooves 111 are arranged around the center S1 of the groove unit 11; for example, The four grooves 111 are arranged at equal angles along the circumference, so that the four grooves 111 are arranged in a cross shape.

The preferred implementation of the shape of the groove 111 of the present creation can be, for example, a circle or a polygon, where the polygon can be, for example, a triangle, a quadrangle, a pentagon, a hexagon, an octagon, or an irregular polygon, and the groove 111 is a polygon. In the embodiment, the predetermined area S of the groove unit 11 is a circular area surrounded by the circumscribed circle of the plurality of polygons, and the predetermined area S is tangent to the circumscribed circle of each polygon, and the diameter of each groove 111 is It is the diameter of the circumscribed circle of its polygon, and a plurality of grooves 111 are distributed around the predetermined area S with equal angles or non-equal angles. In other embodiments, the distribution density of the grooves 111 ringed in the predetermined area S is such that the liquid input end is greater than the non-liquid input end, or when the liquid enters between the substrate 1 and the wafer, the groove 111 where the liquid flow rate is high is ringed The density is greater than the low liquid flow rate, and the arrangement of the groove 111 can effectively balance the liquid filling speed between the substrate and the wafer.

In another implementation, the groove unit of the present creation may include a groove, and the shape of the groove may be, for example, a ring structure. The ring structure may be, for example, a circular ring or a polygonal ring structure. The structure can be, for example, a triangle, a quadrangle, a pentagon, a hexagon, an octagon or an irregular polygon. The ring structure encloses a predetermined area, and the center of the predetermined area is the center of the ring structure. When it is a polygonal ring structure , The center of the predetermined area is the inner center of the polygonal ring structure, and the thickness of the groove is the vertical distance between the two opposite sides of the ring structure.

Furthermore, the diameter or thickness of the grooves 111 is preferably less than half of the distance between the two solder balls 21 of the substrate 2.

The plurality of solder balls 21 on the chip 2 are arranged to correspond to the center S1 of each set of groove units 11 on the substrate 1; therefore, as shown in FIGS. 4 and 5, the chip 2 with the solder balls 21 is flip-mounted on When the substrate 1 and the chip 2 are flip-chip packaged on the surface 10 of the substrate 1, each solder ball 21 corresponds to the predetermined area center S1 of the groove unit 11 and adheres to the connection area S2 on the substrate 1 to form an electrical connection; As shown in Figure 5, a filler material (generally an epoxy-based liquid material) is filled between the substrate 1 and the wafer 2. As there are grooves 111 in various directions around the solder ball 21, the grooves 111 provide The buffer space when the filling material flows, so as to balance the fluidity of the filling material, reduce voids after flip chip packaging, ensure product reliability, and make it easier for water to penetrate between the solder ball 21 and the substrate 1 during the cleaning process The gap is further eliminated the flux around the solder ball 21, and the use of saponification agent is reduced, so as to reduce the manufacturing cost.

The above are only used to explain the preferred embodiments of this creation, and are not intended to impose any formal restrictions on this creation. Therefore, any modification or change related to this creation made under the same creative spirit , Should still be included in the scope of this creative intention protection.

1: substrate 10: Surface 11: Groove unit 111: Groove 2: chip 21: Solder ball S: Reservation area S1: Center S2: Connection area A: Semiconductor components B: substrate B1: Groove C: Solder bump D: Primer E: Solder ball

FIG. 1 is a schematic diagram showing the structure of a conventional chip package; Figure 2 is a schematic top plan view showing the structure of the flip chip substrate of the present invention; Fig. 3 is a schematic diagram showing a cross-sectional side view of the flip-chip substrate structure of the present invention; FIG. 4 is a schematic diagram showing the structure after flip-chip is performed using the flip-chip substrate and chip of this creation; and FIG. 5 is a schematic plan view showing the relative positional relationship between solder balls and grooves after flip chip is performed with the flip chip substrate and chip of the present invention.

1: substrate

111: Groove

2: chip

21: Solder ball

Claims (10)

A flip chip substrate has a surface and is characterized in: A plurality of groups of groove units are formed on the surface, each group of the groove units includes a plurality of grooves, and the grooves of each group of the groove units collectively enclose a predetermined area on the surface, the predetermined The area includes a connecting area, the area of the predetermined area is larger than the area of the connecting area, and the grooves are arranged around the predetermined area. The flip chip substrate according to claim 1, wherein there is a distance between the grooves and the connection area. The flip chip substrate according to claim 1, wherein the connection area is used to connect with a plurality of solder balls of a chip. The flip chip substrate according to claim 1, wherein each group of groove units includes four grooves, and the four grooves are arranged around the center of the groove unit. The flip chip substrate according to claim 4, wherein the four grooves are arranged at equal angles along the circumference. The flip chip substrate according to claim 3, wherein the diameter of the grooves is less than half of the pitch between the solder balls. A flip chip packaging structure, including: A chip with a plurality of solder balls on one side; A substrate has a surface on which a plurality of groups of groove units are formed, each group of the groove units includes a plurality of grooves, and the grooves of each group of the groove units jointly surround the surface Forming a predetermined area, the predetermined area includes a connecting area, the area of the predetermined area is larger than the area of the connecting area, and the grooves are arranged around the predetermined area; Wherein, when the chip is flip-chip on the substrate, each of the solder balls is correspondingly connected to the connection area of each group of groove units. The flip chip package structure according to claim 7, wherein there is a distance between the grooves and the connection area. The flip chip package structure according to claim 7, wherein each group of groove units includes four grooves, and the four grooves are arranged around the center of the groove unit. The flip chip package structure according to claim 7, wherein the diameter of the grooves is less than half of the distance between the solder balls.

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