Disclosure of Invention
The invention aims to provide a surface acoustic wave filter chip packaging manufacturing method and a surface acoustic wave filter chip packaging structure.
The invention provides a manufacturing method of a surface acoustic wave filter chip packaging structure, which comprises the following steps:
providing a surface acoustic wave filter chip with a functional area and a bonding pad on a functional surface;
covering a covering layer on the functional surface, and manufacturing a through hole in the area of the covering layer corresponding to the bonding pad to expose the bonding pad;
electroplating a metal layer in the through hole, and adjusting an electroplating process to form a naturally recessed limiting groove on the upper surface of the metal layer;
and implanting solder balls on the metal layer.
As a further improvement of the present invention, the covering capping layer "specifically comprises the steps of:
covering a first high polymer film layer on the functional surface, and photoetching the first high polymer film layer to expose the functional area and the bonding pad;
and covering a second high polymer film layer on the first high polymer film layer, and photoetching the second high polymer film layer to expose the bonding pad.
As a further improvement of the invention, the method further comprises the following steps after the step of covering the capping layer:
a seed layer is formed on the capping layer.
As a further improvement of the invention, the depth of the limiting groove formed by electroplating is 5-20% of the diameter of the solder ball.
As a further improvement of the invention, the cross section of the limiting groove is circular, the diameter of the cross section of the limiting groove on the upper surface of the metal layer is 45-65% of the diameter of the solder ball, and the diameter of the cross section of the limiting groove is gradually reduced along the inward concave direction of the limiting groove.
As a further improvement of the invention, the limiting groove is formed by sinking downwards along the central axis of the through hole.
The invention also provides a surface acoustic wave filter chip packaging structure, which comprises a surface acoustic wave filter chip, wherein the surface acoustic wave filter chip comprises a functional surface and a non-functional surface which are opposite, the functional surface is provided with a functional area and a bonding pad arranged on the peripheral side of the functional area, the packaging structure also comprises a sealing cover layer, a metal layer and a welding ball, the sealing cover layer covers the functional surface, a closed cavity is formed between the sealing cover layer and the functional area, and a through hole for exposing the bonding pad is formed on the bonding pad;
the metal layer is filled in the through hole, an inward-concave limiting groove is formed on the upper surface of the metal layer, and the metal layer and the limiting groove are of an integral electroplating forming structure;
the solder balls are arranged on the upper surface of the metal layer, and a bulge matched with the limiting groove is formed at the bottom of the solder balls.
As a further improvement of the invention, the depth of the limiting groove is 5-20% of the diameter of the solder ball.
As a further improvement of the invention, the cross section of the limiting groove is circular, the diameter of the cross section of the limiting groove on the upper surface of the metal layer is 45-65% of the diameter of the solder ball, and the diameter of the cross section of the limiting groove is gradually reduced along the inward concave direction of the limiting groove.
As a further improvement of the invention, the limiting groove is coaxially arranged with the through hole.
As a further improvement of the present invention, the capping layer is a high polymer film, and a seed layer is further formed between the metal layer and the through hole.
The invention has the beneficial effects that: according to the invention, the surface acoustic wave filter chip is covered with the sealing layer, the metal layer with the limiting groove formed on the upper surface is directly manufactured in the through hole of the sealing layer through the electroplating process, the limiting groove plays a role in positioning and limiting the implantation of the solder ball, the yield of the solder ball implantation process is improved, and the limiting groove is formed through the electroplating process, so that the process method is simple and convenient.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be clearly and completely described below with reference to the detailed description of the present application and the accompanying drawings. It should be apparent that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art without any inventive work based on the embodiments in the present application are within the scope of protection of the present application.
Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.
For convenience in explanation, the description herein uses terms indicating relative spatial positions, such as "upper," "lower," "rear," "front," and the like, to describe one element or feature's relationship to another element or feature as illustrated in the figures. The term spatially relative position may encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "above" other elements or features would then be oriented "below" or "above" the other elements or features. Thus, the exemplary term "below" can encompass both a spatial orientation of below and above.
As shown in fig. 1, the present invention provides a method for manufacturing a surface acoustic wave filter chip package structure, comprising the steps of:
s1: as shown in fig. 2, a surface acoustic wave filter chip 1 provided with a functional region 111 and pads 112 on a functional surface 11 is provided.
The surface acoustic wave filter chip 1 includes a functional surface 11 and a non-functional surface 12 opposed to each other, and the functional surface 11 is formed with a functional region 111 and pads 112 provided on the peripheral side of the functional region 111.
The functional region 111 includes structures such as a piezoelectric material substrate and a transducer, and is used for realizing functions such as propagation and conversion processing of acoustic signals and electric signals by the surface acoustic wave filter chip 1.
Specifically, in the present embodiment, the pads 112 are uniformly and symmetrically distributed around the functional region 111. In other embodiments, the distribution of the pads 112 may also be adjusted according to the chip layout design.
S2: as shown in fig. 3a and 3b, the functional surface 11 is covered with the cap layer 2, and a through hole 21 is formed in a region of the cap layer 2 corresponding to the pad 112, exposing the pad 112.
The cover layer 2 covers the functional surface 11 and forms a closed cavity 22 with the functional region 111, thereby forming a protection cavity for the saw filter chip 1 and forming a non-interference cavity required by the working region. The capping layer 2 is formed with a through hole 21 exposing the pad 112 on the pad 112, and leaves a space for the saw filter chip 1 to be electrically connected to the outside.
Specifically, in the present embodiment, the "cover capping layer 2" specifically includes the steps of:
as shown in fig. 3a, covering the functional surface 11 with a first high polymer film layer 2a, and photoetching the first high polymer film layer 2a to expose the functional region 111 and the bonding pad 112;
as shown in fig. 3b, a second high polymer film layer 2b is covered on the first high polymer film layer 2a, and the second high polymer film layer 2b is photo-etched to expose the bonding pad 112.
The two high polymer film layers are subjected to photoetching step by step to form the closed cavity 22 on the functional region 111 and the through hole 21 on the bonding pad 112 respectively, the process flow is simple, and the high polymer film layer is adopted as the capping layer 2, so that the thickness of the capping layer 2 can be reduced.
Specifically, in the present embodiment, the capping layer 2 is an epoxy resin film layer.
In another embodiment of the present invention, the capping layer 2 may be a cover plate made of other material such as glass.
Further, as shown in fig. 4, in some other embodiments of the present invention, after covering the capping layer 2, the method further comprises the steps of:
a seed layer 3 is formed on the capping layer 2.
The seed layer 3 is Ti/Cu or TiW/Cu, etc., which is formed between the metal layer 4 and the capping layer 2, plays an adhesion role and serves as a seed layer for forming the metal layer 4 by electroplating.
S3: as shown in fig. 5, a metal layer 4 is formed in the through hole 21 by electroplating, and a limiting groove 41 which is naturally recessed is formed on the upper surface of the metal layer 4 by adjusting the electroplating process.
The metal layer 4 is a metal having good conductive properties such as Cu.
In the electroplating process, a naturally concave pit is formed on the upper surface of the metal layer 4 by adjusting electroplating process parameters such as current density, electroplating solution formula and the like, so that the metal layer 4 with the limiting groove 41 is obtained through the electroplating process, additional processes such as etching and the like are not needed, the process flow is simple, convenient and fast, and the implementation is easy.
After the metal layer 4 is plated on the seed layer 3, the excess seed layer 3 is removed by photolithography or the like.
S4: as shown in fig. 6, solder balls 5 are implanted on the metal layer 4.
And implanting solder balls 5 on the upper surface of the metal layer 4 by electroplating, screen printing, laser ball implantation and other processes.
During ball mounting, the solder ball 5 tends to fill the limiting groove 41 first, and a protrusion 51 matching with the limiting groove 41 is formed at the bottom thereof. And then grow and shape with bellying 51 as the basis to play the effect of location and growth restriction to welding ball 5 through spacing recess 41, make the ball planting rate of accuracy improve.
Furthermore, the depth of the limiting groove 41 is 5% -20% of the diameter of the solder ball 5, and the lower limit of the depth of the limiting groove 41 is limited to 5% of the diameter of the solder ball 5, so as to ensure that the limiting groove 41 has enough depth to limit the solder ball 5; the upper limit of the depth of the limiting recess 41 is defined to be 20% of the diameter of the solder ball 5 to avoid the depth of the limiting recess 41 from being too deep, which results in difficulty in implementation by the plating process.
Furthermore, the cross section of the limiting groove 41 formed by electroplating is circular, the diameter of the cross section of the limiting groove 41 is gradually reduced along the inward concave direction of the limiting groove 41, and the diameter of the cross section of the limiting groove on the upper surface of the metal layer 4 is 45% -65% of the diameter of the solder ball 5, so that the limiting groove 41 can perform a good limiting effect on the solder ball 5, the situation that the limiting groove 41 is too small to perform a limiting effect or too large to perform a limiting effect is avoided, and the limiting groove 41 with the size is easy to realize through an electroplating process.
Specifically, in the present embodiment, the diameter of the solder ball 5 is 100 μm, the depth of the limiting groove 41 is 7-15 μm, and the cross-sectional diameter of the limiting groove at the upper surface of the metal layer 4 is 60 μm.
Furthermore, the limiting groove 41 is formed by sinking downwards along the central axis of the through hole 21, so that the solder ball 5 formed based on the limiting groove 41 can be accurately formed on the through hole 21, and the ball forming quality and the good electrical connection between the ball forming and the substrate are ensured.
As shown in fig. 6, the present invention further provides a surface acoustic wave filter chip 1 package structure, which includes a surface acoustic wave filter chip 1, a capping layer 2, a metal layer 4, and solder balls 5. The surface acoustic wave filter chip 1 includes a functional surface 11 and a non-functional surface 12 opposed to each other, and the functional surface 11 is formed with a functional region 111 and pads 112 provided on the peripheral side of the functional region 111.
The capping layer 2 includes a first polymer film layer 2a and a second polymer film layer 2b, the first polymer film layer 2a exposes the bonding pad 112 and the working area, and the second polymer film layer 2b covers the first polymer film layer 2a to expose the bonding pad 112, thereby forming a sealed cavity 22 covering the functional area 111 and a through hole 21 exposing the bonding pad 112.
The metal layer 4 is filled in the through hole 21, an inward concave limiting groove 41 is formed on the upper surface of the metal layer 4, and the metal layer 4 and the limiting groove 41 are of an integral electroplating forming structure.
The solder ball 5 is disposed on the upper surface of the metal layer 4, and a protrusion 51 matching with the limiting groove 41 is formed on the bottom thereof.
Further, the depth of the limiting groove 41 is 5% -20% of the diameter of the solder ball 5.
Furthermore, the cross section of the limiting groove 41 is circular, the diameter of the cross section of the limiting groove on the upper surface of the metal layer 4 is 45% -65% of the diameter of the solder ball 5, and the diameter of the cross section of the limiting groove is gradually reduced along the inward concave direction of the limiting groove 41.
Further, the stopper groove 41 is provided coaxially with the through hole 21.
In some other embodiments of the present invention, a seed layer 3 is further disposed between the metal layer 4 and the through hole 21.
In summary, the surface acoustic wave filter chip is covered with the sealing layer, the metal layer with the limiting groove formed on the upper surface is directly manufactured in the through hole of the sealing layer through the electroplating process, the limiting groove plays a role in positioning and limiting the implantation of the solder ball, the yield of the solder ball implantation process is improved, and the limiting groove is formed through the electroplating process, so that the process method is simple and convenient.
It should be understood that although the present description refers to embodiments, not every embodiment contains only a single technical solution, and such description is for clarity only, and those skilled in the art should make the description as a whole, and the technical solutions in the embodiments can also be combined appropriately to form other embodiments understood by those skilled in the art.
The above-listed detailed description is only a specific description of a possible embodiment of the present invention and is not intended to limit the scope of the present invention, and equivalent embodiments or modifications made without departing from the technical spirit of the present invention are included in the scope of the present invention.