clamp

Abstract

This disclosure relates to a clamp. A specific embodiment of the clamp may include at least one recess, which may include an opening extending through the thickness of the clamp; and a plurality of truncated corner openings, wherein each of the plurality of truncated corner openings is located at a corner of the at least one recess arranged around the opening. The recess may include angled sides of the opening. The at least one recess may be formed in a body portion of the clamp.

Description

Technical Field

[0001] This application relates generally to fixtures, such as fixtures for handling semiconductor substrates and packages. More specifically, embodiments relate to fixtures for supporting semiconductor substrates during reflow operations. Background Technology

[0002] Various semiconductor package designs have been devised to provide mechanical support for the various semiconductor dies included within the package. Other semiconductor packages protect the semiconductor dies included within the package from shocks or vibrations. Still others help prevent electrostatic discharge (ESD) damage to the semiconductor dies. Summary of the Invention

[0003] A specific implementation of the clamp may include at least one recess, which may include an opening extending through the thickness of the clamp; and a plurality of truncated corner openings, wherein each of the plurality of truncated corner openings is located at a corner of the at least one recess arranged around the opening.

[0004] The recess may include an angled side opening. At least one recess may be formed in the body portion of the fixture.

[0005] The specific implementation of the fixture may include one, all, or any of the following:

[0006] An angled side can form an angle of 13 degrees with the vertical direction.

[0007] The beveled section on each side of a plurality of beveled corner openings may include a rounded edge.

[0008] The opening may consist of only a concave opening on its side.

[0009] The guide portion disposed along the edge of the opening may include a fully angled side.

[0010] A fully angled side can form an angle of 13 degrees with the vertical direction.

[0011] A specific implementation of the fixture may include at least one recess comprising angled sides surrounding an opening, each of the angled sides forming a 13-degree angle with the vertical direction. At least one recess may be formed in the body portion of the fixture and configured to receive a semiconductor substrate therein during a reflow process.

[0012] The specific implementation of the fixture may include one, all, or any of the following:

[0013] The clamp may include at least one beveled corner opening located at the corner of at least one recess.

[0014] The oblique section on the side of at least one oblique corner opening may include a rounded edge.

[0015] At least one beveled corner opening may include an arcuate portion coupled to a rounded edge.

[0016] The opening may consist of only a concave opening on its side.

[0017] The guide portion disposed along the edge of the opening may include a fully angled side.

[0018] A fully angled side can form an angle of 13 degrees with the vertical direction.

[0019] The clamp may include three guides disposed along the edge of the opening, each of the three guides including a fully angled side.

[0020] A specific embodiment of the fixture may include at least one recess including an opening; and a frame including a flexible material coupled into the opening. At least one recess may be formed in a body portion of the fixture. The frame may be configured to receive a semiconductor substrate thereon during a reflow process.

[0021] The specific implementation of the fixture may include one, all, or any of the following:

[0022] Adhesive can be used to hold the frame in the opening.

[0023] One or more springs welded to the opening can be used to hold the frame in the opening, with the one or more springs located between the opening and the frame.

[0024] The flexible material can be one of high-temperature rubber, polyimide, or silicone resin.

[0025] The surface of a frame configured to receive a semiconductor substrate thereon may be positioned in an opening such that the corners of the semiconductor substrate may extend into one or more truncated corner openings of at least one recess.

[0026] The frame may include a gap that aligns with a recessed opening in the side of the opening.

[0027] The above and other aspects, features and advantages will become apparent to those skilled in the art from the specific implementation, the accompanying drawings and the claims. Attached Figure Description

[0028] Specific embodiments will be described below in conjunction with the accompanying drawings, in which similar reference numerals denote similar elements, and:

[0029] Figure 1This is a side cross-sectional view of the reflow fixture engaged with the release fixture during the release of the semiconductor substrate from the recess of the reflow fixture;

[0030] Figure 2 This is a perspective view of a specific embodiment of the recess of a return-flow type fixture;

[0031] Figure 3 This is a perspective view of a specific embodiment of the recess in another specific embodiment of the return-flow type fixture;

[0032] Figure 4 yes Figure 3 A detailed perspective view of a portion of the recess of a return-flow type fixture;

[0033] Figure 5 This is a side cross-sectional view of a specific embodiment of the recess of the reflow type fixture coupled to a semiconductor substrate;

[0034] Figure 6 yes Figure 2 A top view of a specific embodiment of the corner opening of the recess;

[0035] Figure 7 It carries in Figure 3 Top view of another specific implementation of the corner opening of the inclined section on each side of the recess;

[0036] Figure 8 This is a top view of a specific implementation of a return-flow type fixture;

[0037] Figure 9 It is a perspective view of a specific embodiment of a frame coupled in a recess of a specific embodiment of a return-flow type fixture;

[0038] Figure 10 This is a top view of another embodiment of a frame coupled in a recess of one embodiment of a return-flow fixture; and

[0039] Figure 11 This is a top view of a specific implementation of a return-type fixture including the frame. Detailed Implementation

[0040] This disclosure, its aspects, and specific embodiments are not limited to the specific components, assembly steps, or methodological elements disclosed herein. Numerous additional components, assembly steps, and / or methodological elements known in the art and consistent with the intended fixture will be readily apparent and can be used with specific embodiments of this disclosure. Therefore, for example, although a specific embodiment is disclosed, such embodiments and implementation components may include any shape, size, style, type, model, version, measurement, concentration, material, quantity, methodological element, step, etc., known in the art for such fixtures and implementation components and methods, consistent with the intended operation and method.

[0041] Various semiconductor packages include one or more substrates as packaged components. The substrates can be formed from a variety of materials, and can be (non-limiting examples) direct-bonded copper (DBC) substrates, active metal brazing (AMB) substrates, aluminum nitride substrates, alumina substrates, metal-insulating substrates (IMS), lead frames, any combination thereof, or any other substrate type. One or more semiconductor dies are coupled to the substrate (semiconductor substrate), which can be formed from a variety of semiconductor materials, including (non-limiting examples) silicon, silicon carbide, silicon-on-insulator, gallium nitride, gallium arsenide, ruby, sapphire, wide-bandgap materials, or any other semiconductor substrate type. A wide variety of semiconductor dies, including various semiconductor device types, can be included in the various semiconductor package embodiments disclosed herein, including (non-limiting examples) power semiconductor devices, diodes, metal-oxide-semiconductor field-effect transistors (MOSFETs), insulated-gate bipolar transistors (IGBTs), high electron mobility transistors (HEMTs), processors, microprocessors, memories, rectifiers, hybrid devices, or any other semiconductor device type.

[0042] In various package embodiments, the substrate may include one or more traces in one or more layers thereon. In various embodiments, the substrate may include a combination of one or more conductive layers and one or more electrically insulating layers. In some substrate embodiments, the top layer of the substrate is exposed after package formation; in other embodiments, molding compound or potting compound may cover the top layer. For packages using molding compound and substrate, the molding compound may cover various surfaces of the substrate to facilitate the formation of electrically insulating regions. In various package embodiments, various electrical connectors may be used to form electrical connections between the substrate and one or more semiconductor dies included in the substrate, including (non-limiting examples) wire bonding, clips, leads, pins, or any other type of electrical connector.

[0043] In various semiconductor packaging implementations, the package may include a substrate combined with another substrate or with a leadframe to form a desired mechanical / electrical configuration. In cases where the semiconductor package includes a leadframe attached to a substrate using solder material, solder can first be applied to the substrate, and then a reflow oven / system can be used during a reflow operation to hold the leadframe against / support it on the substrate, melting the solder and forming a permanent bond between the leadframe and the substrate.

[0044] To provide mechanical support for the leadframe and substrate during reflow operations and to facilitate consistent process results, various fixtures are employed in different implementations of the methods. (Reference) Figure 1This illustration shows a side cross-sectional view of a semiconductor substrate (substrate) 2 coupled in a recess 4 of a reflow fixture 6 after the solder 8 has been reflowed to form a bond with the lead frame 10. During reflow, the top edge 12 of the reflow fixture 6 supports the lead frame 10 as the solder 8 melts and then cools. Figure 1 An example is illustrated where the reflow jig 6 is placed on the release (ejection) jig 14, with the substrate 2 in a central position. The release (ejection) jig includes a protrusion 16 that, during cooling after reflow is complete, pushes the substrate 2 out of the recess 4 under the influence of gravity and / or bias forces. Since reflow may occur at temperatures exceeding 200°C, if ejection / release is attempted before the reflow jig 6 reaches ambient temperature, the thermal expansion of the material of the reflow jig 6 can cause the recess 4 to shrink to the point where the edge of the recess 4 contacts the edge of the substrate 2 (see dashed areas 18, 20). This behavior may be particularly pronounced when the reflow jig is made of aluminum or an aluminum alloy.

[0045] exist Figure 1 In the illustrated embodiment, substrate 2 is a direct-bonded copper substrate comprising a ceramic layer 22 between two copper layers 24. Since the ceramic layer 22 extends beyond the edges of the copper layers 24, the relatively fragile ceramic layer 22 contacts the metal edges of the recess 2 during release, which may cause the ceramic layer to break and fracture. If breakage / fracture does not immediately lead to failure of the resulting semiconductor package, it may result in field reliability failure, exacerbating the defect. The recess edges of the reflow fixture 6 are oriented at approximately 90 degrees to the vertical direction (ejection / release direction) or substantially parallel to the plane formed by the edges of the ceramic layer / substrate. Unfortunately, this arrangement maximizes the possible surface area of ​​the recess that may contact the substrate during ejection / release, and thus increases the likelihood of breakage / fracture during reflow processing.

[0046] This document discloses various shapes and structures of reflow fixtures and their recesses, along with various methods of forming reflow fixtures. Although the accompanying drawings show detailed views of the structure of a single recess, it should be understood that reflow fixtures may include more than one recess, including structures of the illustrated two-piece, three-piece, four-piece, five-piece, six-piece, or larger design forms.

[0047] refer to Figure 2A specific embodiment of a reflow fixture 26 with a recess 28 is illustrated in perspective view. The recess 28 includes various components adjacent to the opening 30 of the recess 28, which are included as components of the recess 28. As shown, the opening 30 includes two concave openings 32, 34 in the side 36, which begin on and end on the same side 36. It has been observed that the presence of two concave openings 32, 34 on the same side provides unbalanced support for the substrate placed in the recess, thus increasing the observed rotation of the substrate in the recess during processing. Moreover, since the amount of material in the recess 28 on side 36 is different from the amount of material on other sides, the two concave openings 32, 34 cause unbalanced thermal expansion of the recess 28, which leads to rotation / movement of the substrate in the recess during reflow operation.

[0048] Example in Figure 2 Other portions of the recess 28 include guides 38, 40, 42, and 44, which assist in inserting the substrate into the recess and also assist in holding the substrate in the desired orientation during ejection / release. (As in...) Figure 2 As can be observed, the portions of guides 38, 40, 42, and 44 that connect with the edge of opening 30 lie in the same plane as the sides 36, 46, 48, and 50 of opening 30, which are oriented substantially vertically / perpendicularly to the edge of the substrate placed in opening 30. This vertical orientation of the corresponding portions of sides 36, 46, 48, and 50 and guides 38, 40, 42, and 44 means maximizing the surface area of ​​recess 28 available for impacting / impacting the substrate during ejection / release.

[0049] The recess 28 also includes corner openings 52, 54, 56, and 58, which are located at the corners of the recess 28, wherein the corners of the substrate are held in these corner openings during reflow operation. Figure 6 This is a top view of the corner opening 56, showing square / 90-degree edges on each side 60, 62 of the corner opening 56. It has been observed that these square edges on each side 60, 62 where the arcuate portion of the corner opening 56 transitions to each side 46, 36 of the opening 30 creates point contact stresses at these locations on the substrate during reflow and eject / release operations, which could potentially damage the substrate.

[0050] refer to Figure 3Another reflow type fixture 64 is illustrated, which shows a recess 66. The recess 66 includes an opening 68 having sides 70, 72, 74, 76. As illustrated, the opening 68 includes only one recessed opening 78 therein. This has the effect of minimizing the difference in the amount of material on each side 70, 72, 74, 76 of the unbalanced support and the recess 28. This use of a single recessed opening 78 helps to reduce the rotation of the substrate during reflow processing and also helps to reduce substrate movement due to thermal expansion. This reduction in rotation and movement helps to prevent the substrate from contacting and abutting the sides 70, 72, 74, 76, which helps to reduce the possibility of breakage / cracks.

[0051] Figure 4 This is a different perspective view of the side surface 70 of the recess 66, showing how the upper portion 80 of the side surface 70 is angled, as is the corresponding portion 82 of the guide portion 84. This angled portion and the angled portion of the guide portion differ from those illustrated in... Figure 2 The recess 28 is configured to assist in releasing the substrate from the recess during the ejection / release process using the ejection clamp. The angle between the upper portion 80 and the corresponding portion 82 of the guide portion 84 is referred to as the release angle. Tests have shown that the release angle is affected by the material type of the reflow clamp. When the reflow clamp is made of titanium, a release angle as small as about 7 degrees has proven successful in preventing substrate breakage / crack defects. However, when aluminum is used as the material for the reflow clamp, a release angle ranging from about 10 degrees to about 13 degrees is more effective. This is at least in part because the coefficient of thermal expansion of aluminum is greater than that of titanium. The difference in coefficients of thermal expansion means that a larger spacing is required for the release angle of the aluminum recess to achieve the same performance as observed from the titanium recess. Figure 4 As shown, a release angle is applied to the upper portions of all four sides 70, 72, 74, 76 surrounding the opening 68 of the recess 66, and a release angle is applied to each guide portion 84, 86, 88, 90. Figure 5 This illustrates how to measure the release angle and how to apply the release angle to the structure of side 70 and guide 84, and when the substrate 92 is supported / remained in the corner recesses 94, 96, 98, 100 during reflow operation (see...). Figure 3 How is the relationship between the substrate 92 and the side surface 70 in the middle?

[0052] While in certain embodiments, the release angle can be applied to the recess alone to reduce breakage / fracture defects, in some embodiments, the release angle is combined with the previously discussed single concave opening 78 and with modifications to the corner opening. However, in some embodiments, the single concave opening 78 can be omitted, and the recess can be retained. Figure 2 The opening is double-concave. (Reference) Figure 7 Examples Figure 3 Top view of the corner opening 96. This design is related to... Figure 6 Compared to the design shown, it can be observed that each side 102, 104 of the corner opening 96 has been given a beveled section to form a rounded edge. In contrast, the sides 60, 62 of the corner opening 96 have square edges as described above, which increases the proximity of the sides 60, 62 to the corner of the substrate placed in the corner opening. The arcuate portion 116 of the corner opening is coupled to / connects with the rounded edge. Using a beveled section to form the rounded edge increases the distance between the sides 102, 104 and the corner of the substrate placed in the corner opening. Therefore, the likelihood of the sides 102, 104 colliding with the substrate corner during the ejection / release process is reduced, which correspondingly reduces the probability of forming breakage / fracture defects.

[0053] refer to Figure 8 The diagram illustrates a top view of a reflow fixture 106, showing four recesses 108, 110, 112, and 114 formed therein. Each of these four recesses includes a combination of the aforementioned release angle, a single concave opening, and a chamfered corner opening. This particular reflow fixture 106 is a quadruple design capable of handling four substrates and lead frames via a reflow soldering operation, followed by ejecting / releasing the substrates / lead frames from the reflow fixture 106 using a release clamp. Various reflow fixture implementations may include more or fewer recesses.

[0054] In various reflow-type fixture implementations, the use of soft / elastic / flexible materials in the frame coupled to the opening leading to the recess can help mitigate breakage / fracture defects during the reflow process. The use of the frame can be illustrated in... Figure 3 The recessed portion may be used, in combination with, or not in combination with the previously mentioned recessed portion designs in specific embodiments. However, in other embodiments, Figure 2 The recessed design can be achieved using only a frame, which omits any of the previously mentioned recessed designs. (Reference) Figure 9 This illustrates a specific embodiment of the recess 118, including a frame 120 coupled therein. The frame 120 is formed of a flexible material, which can be (non-limiting example) high-temperature rubber, polyimide, silicone, any combination thereof, or any other soft / elastic material capable of withstanding the temperatures of a reflow process. Figure 9In the illustrated embodiment, friction is used to hold the frame 120 in place against the side of the recess. However, in some embodiments, adhesives or bonding agents may be used to hold the frame in place, an option that limits the ability to easily replace the frame 120 if the frame material is damaged or worn. A specific recess design of the recess 118 includes a single concave opening 122, release angles on the upper portions of the guide 126 and the side 1240, and the use of a truncated recess opening 128 similar to that disclosed in this document. Therefore, the frame 120 includes a gap 130 in the frame material at the concave opening 122.

[0055] In other specific implementations of the recess, a spring can be used to couple the frame into the opening of the recess. (See reference) Figure 10 A top view of a specific embodiment of a recess 132 with an opening 134 is shown, wherein a frame 136 is supported / coupled in the opening 134 using a spring 138. The spring 138 is welded to the side of the opening and holds the material of the frame 136 in place by a spring biasing force. Similar to the example illustrated in... Figure 9 In the specific embodiment 120 of the frame, frame 136 includes a gap 140 adjacent to a single concave opening 142 included in the specific embodiment of the recess 132. The spring can be used in conjunction with one, any, all of the previously described recess designs (release angle, single concave opening, or truncated corner opening), or not in conjunction with them.

[0056] Using the frame in the recess can be applied to various reflow fixture designs. Figure 11 An example is a four-unit reflow fixture 144, which includes a frame 148 held in an opening 150 by means of a spring 152. Various reflow fixture embodiments may include more or fewer recesses, allowing the frame within the recesses to process more or fewer substrates. Using a frame made of a flexible material helps mitigate the effects of thermal expansion on the substrate and / or prevents any significant physical contact between the substrate and the hard metal of the recess itself. In this way, the frame 148 helps prevent the formation of breakage / crack defects similar to those previously described. Using a frame made of a flexible material in combination with, or not in combination with, one, any, or all of the previously described recess design elements can further help reduce the likelihood of breakage / crack defects forming in various embodiments.

[0057] Where the above description relates to specific implementations of the fixture and implementation components, sub-components, methods, and sub-methods, it should be apparent that various modifications can be made without departing from its essence, and that these implementations, implementation components, sub-components, methods, and sub-methods can be applied to other fixtures.

Claims

1. A clamp, the clamp comprising: At least one recess, said at least one recess comprising: An opening that extends through the thickness of the clamp; A plurality of beveled corner openings, each of the plurality of beveled corner openings being located at a corner of the at least one recess arranged around the opening; and The angled side of the opening; The at least one recess is formed in the main body portion of the clamp.

2. The clamp of claim 1, wherein, The angled side forms a 13-degree angle with the vertical direction.

3. The clamp of claim 1, wherein, The oblique section on each side of the plurality of oblique corner openings includes a rounded edge.

4. The clamp of claim 1, wherein, The opening consists of only one concave opening on its side.

5. The clamp of claim 1, wherein, The guide portion disposed along the edge of the opening includes a fully angled side.

6. The clamp of claim 5, wherein, The fully angled side forms a 13-degree angle with the vertical direction.

7. A clamp, the clamp comprising: At least one recess, said at least one recess comprising: Angled sides, the angled sides surrounding the opening, each of the angled sides forming a 13-degree angle with the vertical direction; The at least one recess is formed in the main body portion of the fixture and is configured to receive the semiconductor substrate therein during the reflow process.

8. The clamp according to claim 7, the clamp further comprising at least one beveled corner opening, the at least one beveled corner opening being located at the corner of the at least one recess.

9. The clamp of claim 8, wherein, The oblique section on the side of the at least one oblique corner opening includes a rounded edge.

10. The clamp of claim 9, wherein, The at least one beveled corner opening includes an arcuate portion coupled to the circular edge.

11. The clamp of claim 7, wherein, The opening consists of only one concave opening on its side.

12. The clamp of claim 7, wherein, The guide portion disposed along the edge of the opening includes a fully angled side.

13. The clamp of claim 12, wherein, The fully angled side forms a 13-degree angle with the vertical direction.

14. The clamp of claim 12, further comprising three guide portions disposed along the edge of the opening, each of the three guide portions comprising a fully angled side surface.

15. A clamp, the clamp comprising: At least one recess, said at least one recess comprising: Opening; and A frame, the frame comprising a flexible material coupled into the opening; Wherein, at least one recess is formed in the main body portion of the clamp; and The frame is configured to receive a semiconductor substrate thereon during the reflow process.

16. The clamp of claim 15, wherein, The frame is held in the opening using adhesive.

17. The clamp of claim 15, wherein, The frame is held in the opening by one or more springs welded to it, the one or more springs being located between the opening and the frame.

18. The clamp of claim 15, wherein, The flexible material is one of high-temperature rubber, polyimide, or silicone resin.

19. The clamp of claim 15, wherein, The surface of the frame, configured to receive the semiconductor substrate thereon, is positioned in the opening such that the corners of the semiconductor substrate can extend into one or more truncated corner openings of the at least one recess.

20. The clamp of claim 15, wherein, The frame includes a gap that aligns with a concave opening in the side of the opening.

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