Methods and intermediates for manufacturing semiconductor die packages

Abstract

A method of manufacturing a semiconductor die package is provided. The method includes providing a lead frame having a substructure and at least one tie bar, the substructure including a terminal forming portion in electrical communication with the at least one tie bar. The method includes bonding a die to the substructure. The method includes encapsulating the substructure and the die within an encapsulation layer. The method includes performing a first cut through the terminal forming portion and the encapsulation layer to form side terminals while maintaining all tie bars substantially intact. The method includes electroplating the side terminal. The method includes performing a second cut through the tie bar and the encapsulation layer to singulate a semiconductor die package from the lead frame.

Description

Technical Field

[0001] The present invention relates to a method of manufacturing a semiconductor die package and a manufacturing intermediate for a semiconductor die package having improved plating capability. Background Art

[0002] Semiconductors are devices used in electronic circuit systems. An individual semiconductor device is called a die. In order to enable the semiconductor die to be integrated into an electronic circuit system, the semiconductor die is typically placed in a housing (called a die package). Such a die package typically encloses the semiconductor die in a piece of insulating material (such as plastic).

[0003] In order to allow electrical communication between the die and any circuits in which the die will be incorporated, the die package includes several terminals. In some configurations, the terminals extend outward from the die package housing. This configuration is called a "leaded" die package. In other configurations, the terminals are formed flush with the sides of the die package housing. This configuration is called a "leadless" die package.

[0004] US 9,443,791 B2 describes a prior art method 100 of manufacturing a leadless die package, which is summarized below with reference to FIGS. 1 to 4 .

[0005] 1 and 2, the method 100 begins at step 102 by providing a lead frame 200 having a plurality of substructures 202 arranged in a grid-like pattern. Four such substructures 202 are shown in FIG.

[0006] Each substructure 202 includes a first die connection portion 204 associated with a first terminal forming portion 206, a second terminal forming portion 208, and a third terminal forming portion 210. The third terminal forming portion 210 is directly connected to the first die connection portion 204, while the first terminal forming portion 206 and the second terminal forming portion 208 are indirectly connected to the first die connection portion 204 via tie bars 222. The third terminal forming portion 210 is positioned on a first side of the substructure 202, while the first terminal forming portion 206 and the second terminal forming portion 208 are positioned on a second, opposite side of the substructure 202.

[0007] Each substructure 202 also includes a second die connection portion 212 associated with a fourth terminal forming portion 214, a fifth terminal forming portion 216, and a sixth terminal forming portion 218. The sixth terminal forming portion 218 is directly connected to the second die connection portion 212, while the fourth terminal forming portion 214 and the fifth terminal forming portion 216 are indirectly connected to the second die connection portion 212 via a further tie bar 222. The third terminal forming portion 214 and the fourth terminal forming portion 216 are positioned on a first side of the substructure 202, while the sixth terminal forming portion 218 is positioned on a second side of the substructure 202.

[0008] The third terminal forming portion 210, the fifth terminal forming portion 216, and the fourth terminal forming portion 414 are arranged in sequence from left to right on the first side of the substructure 202 and are substantially aligned with each other along the horizontal axis. The first terminal forming portion 206, the second terminal forming portion 208, and the sixth terminal forming portion 218 are arranged in sequence from left to right on the second side of the substructure 202 and are substantially aligned with each other along the horizontal axis.

[0009] The substructures 202 are arranged into a series of longitudinally arranged columns 220 separated by tie bars 222. In each pair of adjacent substructures 202 in a given column, a first terminal forming portion 206 of a first one of the substructures 202 is defined by the same portion of the lead frame 200 as a third terminal forming portion 210 of an adjacent one of the substructures 202. Similarly, a second terminal forming portion 208 of the first substructure 202 is defined by the same portion of the lead frame 200 as a fifth terminal forming portion 216 of an adjacent one of the substructures 202. Finally, a sixth terminal forming portion 219 of the first substructure 202 is defined by the same portion of the lead frame 200 as a fourth terminal forming portion 214 of an adjacent one of the substructures 202.

[0010] The tie bars 222 run alongside each column 202 and are electrically connected to each die attach portion 204 , 212 and terminal forming portions 206 to 210 , 214 to 218 .

[0011] Next, in step 104, a first die 224 is arranged on each of the first die connection portions 204 and bonded to each of the first die connection portions, and a second die 226 is arranged on each of the second die connection portions 212 and bonded to each of the second die connection portions. This bonding is performed using a conductive adhesive (e.g., solder, etc.).

[0012] In step 106, die bonding wires 228 are bonded between the upper side of the first die 224 and the first terminal forming portion 206 and the second terminal forming portion 208, and between the upper side of the second die 226 and the fourth terminal forming portion 214 and the fifth terminal forming portion 216. In FIG2 , the die bonding wires 228 are shown in thick solid lines. The purpose of the die bonding wires 228 is to provide electrical connections between the communication and / or power input and / or output portions located on the upper surfaces of the dies 224, 226 and the terminal forming portions 206, 208, 214, 216.

[0013] In step 108, sacrificial plating wire 230 is bonded between tie bar 222 and second terminal forming portion 208 and between tie bar 222 and fourth terminal forming portion 216. In Fig. 2, plating wire 230 is shown in bold dashed line. As will be discussed below, the purpose of plating wire 230 is to ensure that all terminal forming portions 260 to 210, 214 to 218 are in electrical communication to allow electroplating to be performed at a later stage.

[0014] Subsequently, in step 110 , the assembly is encapsulated in an electrically insulating material, such as plastic, to form an encapsulation layer.

[0015] 1 and 3 , in step 112 , a first series of cuts 232 are performed. The first cuts 232 extend in a transverse direction and extend substantially continuously across all grids of the subassembly 202 . Specifically, each cut 232 in the first series of cuts removes material forming the tie bars 222 and the first terminal forming portions 206 , the second terminal forming portions 208 , the third terminal forming portions 210 , the fourth terminal forming portions 214 , the fifth terminal forming portions 216 , and the sixth terminal forming portions 218 across the entire width of the grid. Each cut 232 forms a number of transverse channels 234 that extend continuously across the entire width of the grid of the substructure 202 . Removing the first terminal forming portion 206, the second terminal forming portion 208, the third terminal forming portion 210, the fourth terminal forming portion 214, the fifth terminal forming portion 216, and the sixth terminal forming portion 218 exposes the ends of the lead frame 200 to define corresponding first side terminals 236, second side terminals 238, third side terminals 240, fourth side terminals 242, fifth side terminals 244, and sixth side terminals 246. As a result of the cutting process, the side terminals 236-246 are formed flush with the sides of the channel 234. The first series of cuts 232 are performed using a so-called "chopper," which is a rotating disk cutter similar to a circular saw.

[0016] The surfaces of the newly formed side terminals 236 to 246 need to be plated to protect them from undesirable corrosion / oxidation. Therefore, in step 114, the lead frame 200 is plated to protect the newly formed side terminals 236 to 246. During this process, current is provided to the lead frame 200, which is carried to all side terminals via a combination of the remaining portion of the tie bar 222 and the plating wire 230.

[0017] 1 and 4, after the electroplating is completed, in step 116, a second series of cuts 248 are performed. The second cuts 248 are generally performed orthogonally to the first cuts 232. The second cuts 248 remove the tie bars 222 and form longitudinal channels 250. After forming the channels 250, the individual substructures 202 have been singulated into independent die packages 252. As with the first cuts 232, the second cuts 248 are also performed using a "shredder".

[0018] Referring again to step 114 and Figure 3, in the absence of the plated wire 230, once the transverse channel 234 is cut, it is impossible to provide current to all exposed side terminals 236 to 246. However, referring to step 116 and Figure 4, once the longitudinal channel 250 is cut, the plated wire 230 is no longer functional.

[0019] It is therefore an object of the present invention to mitigate or eliminate the need to provide sacrificial plated wires 230 of the type described above associated with the prior art. It is a further object of the present invention to mitigate or eliminate one or more disadvantages of the prior art, whether described herein or elsewhere. Summary of the invention

[0020] According to a first aspect of the present invention, there is provided a method of manufacturing a semiconductor die package, the method comprising: providing a lead frame having a substructure and at least one tie bar, the substructure comprising a terminal forming portion in electrical communication with the at least one tie bar;

[0021] bonding the die to the substructure;

[0022] encapsulating the substructure and the die within an encapsulation layer;

[0023] performing a first cut through the terminal forming portion and the encapsulation layer to form the side terminal while keeping all tie bars substantially intact;

[0024] Plating the side terminals; and

[0025] A second cut is performed through the tie bars and encapsulation layer to singulate the semiconductor die packages from the leadframe.

[0026] Since the tie bar remains substantially intact when the first cut is performed, electrical connectivity between the tie bar and the terminal forming portion is maintained when the side terminal is formed. This therefore ensures that the newly formed side terminal is electrically connected to the tie bar after the first cut is completed. Thus, for the purpose of electroplating, the tie bar can be used to carry current to and / or from the newly formed side terminal. Specifically, since this electrical connectivity is provided by the tie bar, it is not necessary to provide electrical connectivity via any additional sacrificial bonding wire. This reduces the number of wire connections, thereby greatly simplifying the manufacturing process and reducing material waste.

[0027] The term "substructure" is intended to refer only to the portion of the leadframe that will be singulated into the final semiconductor die package.

[0028] The term "substantially complete" does not exclude some degree of cutting of the tie bar, as long as the tie bar remains electrically connected to the newly formed side terminals once the first cut is completed.

[0029] The term "terminal forming portion" encompasses a portion of the lead frame which, when cut, will form a side terminal of the substructure.

[0030] The term "side terminals" encompass exposed portions of a leadframe suitable for connection to circuitry that will be integrated into the die package.

[0031] It will be appreciated that the lead frame may have a single tie bar or multiple tie bars. However, in the case where the lead frame includes multiple tie bars, all tie bars must remain substantially intact after the first cut.

[0032] The substructure may include a plurality of terminal forming portions, and the step of performing a first cut includes cutting through the plurality of terminal forming portions and the encapsulation layer to form a plurality of side terminals while keeping the tie bar substantially intact. The terminal forming portions may be substantially aligned along the transverse axis. The first cut need not be a single cut, and may include a series of cuts to form a side terminal at each corresponding terminal forming portion.

[0033] The first cut may be performed using laser cutting. Laser cutting is very suitable for the performance of the first cut (or first series of cuts) as it is very precise. However, alternatively, substantially any form of cutting may be performed.

[0034] Performing the second cut may include completely removing the tie rods. That is, after the second cut (or second series of cuts), in such an embodiment, substantially all of the tie rods will be removed.

[0035] The lead frame may define a plurality of said substructures electrically connected via tie bars. Each substructure may also be electrically connected to an adjacent substructure via their respective terminal forming portions. In addition, the step of bonding the die to the substructure may include bonding the die to each of the plurality of substructures. In addition, the step of encapsulating the substructure and the die within an encapsulation layer may include encapsulating each of the plurality of substructures and their associated die within an encapsulation layer. The step of performing a first cut may include performing a first series of cuts through the terminal forming portions and the encapsulation layer to form side terminals in each substructure while keeping the tie bars substantially intact.

[0036] A plurality of substructures may be arranged in a column. The lead frame may include a plurality of said columns, and adjacent columns may be interposed by tie bars electrically connected to each substructure in said adjacent columns. In addition, the step of performing a second cut may include performing a second series of cuts through the tie bars and the encapsulation layer to singulate a plurality of semiconductor die packages from the lead frame.

[0037] The first series of cuts may extend in a generally transverse direction. The transverse direction corresponds to the row direction of the substructures. The second series of cuts may extend in a generally longitudinal direction. The longitudinal direction corresponds to the column direction of the substructures.

[0038] The method may further include the step of bonding a wire between the upper surface of the die and the terminal forming portion.

[0039] According to a second aspect of the present invention, there is provided a manufacturing intermediate for semiconductor die packaging, the manufacturing intermediate comprising:

[0040] a lead frame defining a plurality of substructures arranged in a grid extending in a lateral direction and a longitudinal direction, the lead frame including a plurality of longitudinally extending tie bars positioned between laterally adjacent pairs of the substructures;

[0041] a plurality of dies, each die being bonded to a separate one of the substructures;

[0042] an encapsulation layer encapsulating the lead frame and the die; and

[0043] a plurality of laterally extending channels penetrating the encapsulation layer and the leadframe, the channels being positioned between each pair of longitudinally adjacent substructures and including side terminals in electrical communication with the tie bars;

[0044] The tie rods extend longitudinally between multiple pairs of channels that are adjacent to each other in the transverse direction.

[0045] The term "manufacturing intermediate for semiconductor die package" encompasses an assembly of sub-components configured to form one or more semiconductor die packages. That is, the manufacturing intermediate is the product of an incomplete process step in the manufacture of semiconductor die packages.

[0046] Since the manufacturing intermediate includes tie bars extending longitudinally between laterally adjacent pairs of channels, and since the tie bars are in electrical communication with the side terminals, the tie bars are able to provide current to all side terminals in the manufacturing intermediate. Therefore, electroplating can be performed on all side terminals of the manufacturing intermediate.

[0047] The channels may be aligned in laterally extending rows, each row comprising a series of channels.

[0048] The ties may extend longitudinally substantially across the entire longitudinal dimension of the substructure grid. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] A detailed description of the present invention is provided below with reference to the accompanying drawings, in which:

[0050] FIG1 is a flow chart of a prior art method for manufacturing a semiconductor die package;

[0051] FIG. 2 is a schematic plan view of a prior art lead frame according to the method of FIG. 1 after completing the step of bonding a sacrificial plated wire;

[0052] 3 is a schematic plan view of a prior art lead frame according to the method of FIG. 1 after completing the steps of performing a first series of cuts;

[0053] 4 is a schematic plan view of a prior art lead frame according to the method of FIG. 1 after completing the step of performing a second series of cuts;

[0054] Figure 5 is a flow chart of a method for manufacturing a semiconductor die package according to the present invention;

[0055] Figure 6 After completing the step of bonding the die leads, Figure 5 A schematic plan view of a lead frame of the method;

[0056] Figure 7 After the first series of cuts are completed, Figure 5 a schematic plan view of a lead frame of the method; and

[0057] Figure 8 After the second series of cuts are completed, Figure 5 A schematic plan view of a lead frame of the method. DETAILED DESCRIPTION

[0058] Figures 5 to 8 A method 300 and a corresponding lead frame assembly 400 for manufacturing a semiconductor die package according to the present invention are shown. The method 300 is substantially similar to the prior art method 100 described with respect to FIG. 1 , and therefore corresponding reference numerals have been used starting with 300 . Figures 6 to 8 The depicted leadframe assembly 400 is substantially similar to the prior art leadframe assembly 200 described with respect to FIGS. 2 to 4 , and therefore corresponding reference numerals have been used beginning with 400 .

[0059] Steps 302 to 306 of the method 300 of the present invention are substantially the same as steps 102 to 106 of the prior art method 100 described above. However, the prior art step 108 of incorporating the sacrificial plated wire 230 is omitted from the method 300 of the present invention. Figure 6 As shown, no sacrificial plated wire is provided on the lead frame 400 of the present invention.

[0060] Step 310 of the method 300 of the present invention is substantially the same as step 110 of the prior art method 100 described above.

[0061] The step 312 of the method 300 of the present invention in which the first series of cuts are performed is different from the corresponding step 112 of the prior art method 100 described above. Specifically, although the step 112 of the prior art includes cutting across the entire lateral width of the grid of the substructure 202, in the step 312 of the present invention, only the terminal forming portions 406 to 410, 414 to 418 and their associated portions of the encapsulation layer are cut. Specifically, each cut 432 extends through the first terminal forming portion 406 and / or the third terminal forming portion 410, the second terminal forming portion 408 and / or the fifth terminal forming portion 416, and the sixth terminal forming portion 418 and / or the fourth terminal forming portion 414. That is, the cut 432 extends through each lateral terminal forming portion of three groups. However, the tie rods 422 of the encapsulation layer and their associated portions are not cut during this process and remain substantially intact.

[0062] refer to Figure 7 , which enables the formation of a series of channels 434 extending laterally positioned between each pair of longitudinally adjacent substructures 402. The tie rods 422 extend longitudinally between each pair of transversely adjacent channels 434, which allows power to be distributed to each row of the grid. Therefore, compared to the prior art, in the present invention, the tie rods 422 remain electrically connected to all side terminals 436 to 446. In other words, by discretizing the continuous transverse cuts 232 of the prior art into a series of smaller cuts inserted by the longitudinally extending tie rods 422, the present invention maintains that all side terminals 436 to 446 in the lead frame 400 are electrically connected to each other. Therefore, the current required for electroplating can be provided to all side terminals 436 to 446 via the tie rods 422 without including the aforementioned type of sacrificial plating wires 230. By avoiding the need to provide sacrificial plating wires 230, the present invention reduces the complexity of the entire manufacturing process and reduces material waste.

[0063] Furthermore, because the tie bars 422 remain intact to provide electrical connectivity to all of the side terminals 436 - 446 , the method of the present invention may be used to manufacture die packages including substantially any number of side terminals without the need to provide sacrificial plated wires 230 .

[0064] It should be understood that while the tie rods 422 must remain substantially intact during the execution of the first series of cuts 432, some degree of removal may be performed if the tie rods 422 remain capable of transmitting current between adjacent rows of substructures 402 in the grid. Thus, at a minimum, the tie rods 422 cannot be completely severed, and preferably, as much as possible (if not all) of the tie rods 422 should remain after the first series of cuts 432 are performed.

[0065] Preferably, the step 312 of performing the first series of cuts according to the present invention is performed using a laser cutter. It has been found that laser cutters are particularly suitable for this application because they provide very precise control over the cutting positions. The size of the channels 434 is generally very small, and therefore the ease of manufacturing is increased by using the precise control provided by the laser cutter. However, it should be understood that, in principle, it is possible to form the series of channels 434 using any suitable processing method (including a so-called "chopper").

[0066] After the first series of cuts are completed in step 312 , the side terminals 436 - 446 are plated in step 314 .

[0067] Finally, reference Figure 5 and Figure 8 In step 314, a second series of cuts 448 are performed in substantially the same manner as step 114 of prior art method 100. Specifically, in second cutting step 314, substantially all of tie bars 422 are removed, thus resulting in singulation of individual die packages 452. This step is preferably performed using a "shredder", but may also be performed by laser cutting.

[0068] Although lead frame 400 includes a rectangular arrangement grid of substructures 402, it should be understood that in alternative embodiments, substructures 402 may not be arranged in a rectangular grid. For example, substructures 402 may be inlaid in a triangular pattern, a hexagonal pattern, or positioned in any arbitrary layout. In addition, adjacent rows of substructures 402 may be staggered relative to each other. However, in order to perform the method of the present invention, after the first series of cuts 432, tie bars 422 must remain substantially intact to maintain electrical communication between all side terminals 436 to 446.

[0069] Furthermore, the tie rods 422 need not extend exactly orthogonal to the rows of substructures 402, but may be tilted at any angle. In this arrangement, the second cut 448 may be tilted at the same angle as the tie rods 422 to remove substantially all of the tie rods 422.

[0070] It should be understood that the method 300 of the present invention is equally applicable to manufacturing a single die package 452 from a leadframe 400 including a single substructure 402 as it is to manufacturing multiple die packages 452 from a leadframe including multiple substructures 402 .

[0071] It should be understood that although the cuts 432 extend through each lateral triplet of terminal forming portions to form a continuous channel 434, in alternative embodiments, the individual terminal forming portions 406-410, 414-418 may be cut independently to form an independent channel 434 for each terminal forming portion 406-410, 414-418. In such an embodiment, it may be necessary to subsequently perform an additional series of cuts to completely singulate the individual die packages 452.

Claims

1. A method for manufacturing a semiconductor die package, the method comprising: providing a lead frame having a substructure and at least one tie bar, the substructure including a terminal forming portion in electrical communication with the at least one tie bar; bonding a die to the substructure; encapsulating the substructure and the die within an encapsulation layer; performing a first cut through the terminal forming portion and the encapsulation layer to form a side terminal while keeping all tie bars substantially intact; electroplating the side terminals; as well as A second cut is performed through the tie bars and the encapsulation layer to singulate semiconductor die packages from the lead frame.

2. The method of claim 1, wherein the substructure comprises a plurality of terminal forming portions, and the step of performing the first cut comprises cutting through the plurality of terminal forming portions and the encapsulating layer to form a plurality of side terminals while keeping the tie bar substantially intact.

3. A method according to any preceding claim, wherein the first cutting is performed using laser cutting.

4. A method according to any preceding claim, wherein performing the second cut comprises completely removing the tie rod.

5. A method according to any preceding claim, wherein said leadframe defines a plurality of said substructures, said plurality of said substructures being electrically connected via said tie bars, each substructure being further electrically connected to an adjacent substructure via a respective terminal forming portion; wherein the step of bonding a die to the substructure comprises bonding a die to each of the plurality of substructures; wherein the step of encapsulating the substructures and the die within the encapsulation layer comprises encapsulating each of the plurality of substructures and its associated die within the encapsulation layer; and Wherein the step of performing the first cuts comprises performing a first series of cuts through the terminal forming portion and the encapsulation layer to form side terminals in each substructure while leaving the tie bar substantially intact.

6. The method of claim 5, wherein the plurality of substructures are arranged in a column, the lead frame comprises a plurality of the columns, and adjacent columns are interposed by tie bars electrically connected to each substructure in the adjacent columns; and Wherein the step of performing second cuts includes performing a second series of cuts through the tie bars and the encapsulation layer to singulate a plurality of semiconductor die packages from the lead frame.

7. A method according to claim 5 or 6, wherein the first series of cuts extend in a generally transverse direction.

8. A method according to claim 6 or 7, wherein the second series of cuts extends in a generally longitudinal direction.

9. A method according to any preceding claim, further comprising the step of bonding a wire between the upper surface of the die and the terminal forming portion.

10. A manufacturing intermediate for semiconductor die packaging, the manufacturing intermediate comprising: a lead frame defining a plurality of substructures arranged in a grid extending in a lateral direction and a longitudinal direction, the lead frame including a plurality of longitudinally extending tie bars positioned between laterally adjacent pairs of the substructures; a plurality of dies, each die bonded to a separate one of the substructures; an encapsulation layer, the encapsulation layer encapsulating the lead frame and the tube die; as well as a plurality of laterally extending channels penetrating the encapsulation layer and the leadframe, the channels being positioned between each pair of longitudinally adjacent substructures and including side terminals in electrical communication with the tie bars; The tie rods extend longitudinally between a plurality of laterally adjacent pairs of channels.

11. A manufacturing intermediate according to claim 10, wherein the channels are aligned in laterally extending rows, each row comprising a series of channels.

12. A manufacturing intermediate as claimed in claim 10 or 11 wherein the tie rods extend longitudinally across substantially the entire longitudinal dimension of the grid of the substructure.

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