TWM510539U - Modified spring cushion for film frame shipper - Google Patents

Abstract

A film frame shipper. Various embodiments of the disclosure provide enhanced prevention against the jumping of film frames within the film frame shipper. In addition, the structures that prevent jumping also augment alignment of the film frames during loading into the shipper. Furthermore, in certain embodiments, these structures enable a closer tolerance fit between the thickness of the film frames and the registration slots, thereby reducing play between the film frame and the registration slot and attendant particle generation.

Description

Modified spring pad for use in a film carriage [related application]

The present application claims the benefit of U.S. Provisional Patent Application Serial No. Ser.

The present invention relates generally to wafer transfer devices and, more particularly, to film frames or tape frame shippers.

The film holder or tape holder is generally constructed of a stainless steel frame and a film extending across the frame. The film has a binder on one side thereof. After processing, a circular semiconductor wafer is typically placed on the film. After being positioned on the film, the semiconductor wafer can be sliced into individual sheets (eg, wafers), transported for further processing, or stored. The wafers used in the semiconductor processing industry are growing larger and thinner, and these wafers present processing, transport, and storage issues due to their greater friability. To this end, in order to carry a film holder having such a large and thin wafer, the conventional film holder wafer carrier can be modified.

Membrane transporters are widely used in the semiconductor manufacturing industry to transport membrane frames. A variety of film holder conveyors provide a safe and efficient way to transport and store up to 25 wafers mounted to a film holder or single-divided. a container top cover pad enables reuse of the conveyor Set. There may be a film holder transfer device suitable for transporting a film holder of wafers having diameters of 300 mm, 200 mm, and 150 mm.

It is known that a membrane holder loaded in a conventional membrane carrier transfer device "jumps" during an impact event. That is, the deformation induced on the outer casing of the film holder transfer device allows the film holder to be detached from the designated registration slot. This situation can cause the resident wafer to be damaged and collide and damage adjacent wafers.

A film holder transfer device that also reliably holds the film holder in a designated alignment position during an impact event would be welcome.

Various embodiments of the present invention provide enhanced precautions for the beating of the film holder in a film holder transfer device. In addition, the structure for preventing bounce also enhances the alignment of the film holder during loading into the conveyor. Moreover, in some embodiments, the structures achieve a tighter tolerance fit between the thickness of the film holder and the alignment slots, thereby reducing play between the film holder and the alignment slots and reducing accompanying Particles are produced.

Each wafer is supported on a metal or polymer wafer support ring or shelf. The wafer support ring is received in and held by one of the spring cushions positioned at the top and/or bottom of the film holder transfer device. The spring pad applies a radial force to the membrane holder to secure each membrane holder within a respective alignment slot, thereby reducing movement of the membrane holder within the alignment slot during delivery and reducing particle transfer or generation. In some embodiments, the spring pad is removable and/or replaceable and may include a snap feature for facilitating coupling of the spring pad to the conveyor. Other features of the film carriage transfer include: a positive snap latch for securing the closure of the conveyor; a non-blocking latch and stackable design (non-obtrusive latch and stackable design) for reducing storage space and reducing transmission costs; and rounded and sloping sides for reducing water retention during cleaning. The film holder transfer device can use an Electro-Static discharge (ESD) material. Radio frequency identification (RFID) and laser marking options can also be used.

20‧‧‧ Film holder conveyor

22‧‧‧ Container

24‧‧‧ Cover

26‧‧‧Internal room

28‧‧‧Model base

32‧‧‧ side

34‧‧‧Guide

36‧‧‧Spring shelf/spring holder

36a‧‧ ‧ spring frame

36b‧‧ ‧ spring frame / spring frame pad

38‧‧‧Slotted track

40‧‧‧membrane frame

42‧‧‧

44‧‧‧ outer edge

46‧‧‧Adhesive diaphragm

48‧‧‧ wafer

52‧‧‧ opposite side / first opposite side

54‧‧‧ opposite side / second opposite side

56‧‧‧ front and rear direction

58‧‧‧Main pad/main pad

62‧‧‧Aligning slots

64‧‧‧ transverse direction

72‧‧‧First comb structure

74‧‧‧First comb-like projection

76‧‧‧Vertical direction

78‧‧‧First comb gap/comb gap

82‧‧‧Second comb structure

84‧‧‧Second comb-like projection

88‧‧‧Second comb gap

92‧‧‧ proximal end

94‧‧‧ distal

96‧‧‧Conical profile

98‧‧‧ protruding axis

102‧‧‧through slot

110‧‧‧Base comb structure/base comb

112‧‧‧ base

114‧‧‧Base combs

116‧‧‧Alignment track

118‧‧‧Base comb gap/gap

122‧‧‧ rail height

124‧‧‧ proximal end

126‧‧‧Gap shift

128‧‧‧ distal end

132‧‧‧Highlight height

140‧‧‧Side comb structure

142‧‧‧Side comb-like projections

148‧‧‧ side comb gap

152‧‧‧ gap depth

154‧‧‧ proximal end

156‧‧‧Highlight height

158‧‧‧ distal end

162‧‧‧Slot depth

164‧‧‧facing upwards

166‧‧‧ slot

172‧‧‧ Minimum gap size

184‧‧‧隅角

186‧‧‧ protruding parts

1 is an assembled view of a film frame conveying device and a resident film holder in an embodiment of the present invention; and FIG. 2 is a container mounted to a container of the film frame conveying device shown in FIG. FIG. 3 is a perspective view of a film holder conveying device shown in FIG. 1; FIG. 4 is a cross-sectional view of the film frame conveying device shown in FIG. 1; and FIG. 5 is a film frame. One of the plan views; FIG. 6 is a perspective view of a spring frame cushion in an embodiment of the present invention; FIG. 6A is an enlarged view of one of the spring frame cushions shown in FIG. 6 in an embodiment of the present invention. 3 is a perspective view of a spring holder pad in an embodiment of the present invention; and FIG. 8 is a sectional view of any one of the spring holders shown in FIG. 6 or FIG. 7; FIG. A perspective sectional view of a film frame conveying device in an embodiment of the present invention; FIG. 10 is an enlarged perspective sectional view showing one side comb structure shown in FIG. 9 in an embodiment; An enlarged cross-sectional view of one of the bottom comb structures shown in Fig. 9 in an embodiment of the present invention; Figure 12 is a schematic cross-sectional view showing a film holder conveying device having an upper spring holder pad and a lower spring holder pad according to an embodiment of the present invention; and Figure 13 is an embodiment of the present invention having an upper portion A schematic cross-sectional view of a spring frame mat and a pair of lower spring holder pads.

Referring to Figures 1 through 4, a film frame transport device 20 of one embodiment of the present invention is illustrated. The film holder transport unit 20 includes a container 22 and a lid 24 that forms a closure on the container portion to define an interior chamber 26 for storing a plurality of membrane holders 28. The container 22 includes a side portion 32 that can include a guide 34 (Fig. 2) for guiding the membrane holder 28 into the container 22. A spring carrier pad 36 is coupled to at least one of the container 22 and the cover 24. In one embodiment, the shelf pad 36 is removably mounted to the slotted rail 38 on the container 22 or cover 24.

Referring to Figure 5, a film frame 40 is illustrated. The membrane holder 40 includes a frame 42 that defines an outer edge 44. An adhesive membrane 46 spans the frame 42 and a wafer 48 is adhered to the adhesive diaphragm 46.

Referring to Figures 6 through 8, there are shown several versions of the spring frame 36 of the presently described embodiment. The spring holder 36 is specifically referred to as a spring holder 36a (Fig. 6) and a spring holder 36b (Fig. 7), and is generally or collectively referred to as a spring holder 36. The spring holder 36 includes opposing sides 52 and 54 that extend in a fore/aft direction 56 and support a main pad portion 58 therebetween, the main pad portion 58 defining a plurality of alignment slots 62 . Each of the alignment slots 62 extends in a transverse direction 64 that is orthogonal to the front-rear direction 56, and the alignment slots 64 are adapted to engage the outer edge 44 of the film holder 40 to limit movement of the film holder 40 in the front-rear direction 56.

In various embodiments, a first comb structure 72 includes A plurality of first comb-like projections 74 extend from a first opposing side 52 of the spring holder pad 36 in a vertical direction 76. (The vertical direction 76 is orthogonal to the front-rear direction 56 and orthogonal to the transverse direction 64.) The first comb-like projections 74 are spaced apart from one another to define a plurality of first comb-like gaps 78. The first comb-like protrusions 74 of the first comb-like protrusions 74 are adapted to engage and receive the outer edge of the film holder 40, and each of the first comb-shaped gaps 78 is defined by the first comb-shaped structure 72. Between adjacent ones of the first comb-like projections 74, the comb-like gaps 78 are adapted to engage the outer edge 44 of the membrane holder 40 to limit movement of the outer edge 44 in the fore-and-aft direction 56. Additionally, each of the alignment slots 62 is aligned with one of the first comb gaps 78 in a lateral direction 64.

In some embodiments, a second comb-like structure 82 includes a plurality of second comb-like projections 84 that extend from the second opposing side 54 of the spring carrier pad 36 in a vertical direction 76. extend. The second comb-like projections 84 are spaced apart from one another to define a plurality of second comb-like gaps 88. Adjacent ones of the second comb-like projections 84 are adapted to engage and receive the outer edge 44 of the membrane frame 40, and each of the second comb-like gaps 88 is defined by the second of the second comb-like structures 82. Between the adjacent ones of the comb-like projections 84, each of the second comb-like gaps 88 is adapted to engage the outer edge 44 of the membrane holder 40 to limit movement of the outer edge 44 in the front-rear direction 56. Additionally, each of the alignment slots 62 is aligned with one of the second comb gaps 88 in a lateral direction 64.

In various embodiments, at least a portion of the first comb-like projections 74 and/or the second comb-like projections 84 each include a proximal end 92 and a distal end 94 and are defined to extend in the lateral direction 64. A tapered profile 96. The tapered profile 96 can be symmetrical about a projection axis 98 (FIG. 6A) extending in a vertical direction 76 that slopes from the proximal end 92 to the distal end 94 toward the projection axis 98. In one embodiment, at least a portion of the tapered profile 96 is arcuate (not shown).

In an embodiment, the primary pad portion 58 defines a plurality of through-slots 102. Each of the through slots 102 is disposed between adjacent alignment slots of the alignment slots 62.

Referring to Figures 9 through 11, it discloses other comb structures in the present creative embodiment. In one embodiment, at least one base comb structure 110 is disposed on a base portion 112 of the container 22, the base comb structure 110 includes a plurality of base comb projections 114, the base comb projections 114 from the container 22 The base portion extends in a vertical direction 76 into the interior chamber 26, the base comb projections 114 being spaced apart from each other to define a plurality of base comb gaps 118. Adjacent ones of the base comb projections 114 are adapted to engage and receive the outer edge 44 of the membrane frame 40, and each of the base comb gaps 118 are defined by the base comb projections of the base comb structure 110. 114 among the neighbors.

The base comb gaps 118 are adapted to engage the outer edge 44 of the film holder 40 to limit movement of the outer edge 44 in the front-rear direction 56. In addition, each of the alignment slots 62 of the spring holder pads 36 is aligned with a respective one of the base comb gaps 118. That is, each of the base comb gaps 118 is centered on a plane that is also centered on one of the alignment slots 62 that is orthogonal to the front and rear direction 56. In one embodiment, at least a portion of the base comb projections 114 comprise a tapered profile as depicted in FIG. 6A.

In one embodiment, an alignment rail 116 extends from the base portion and extends in a front-rear direction 56 that defines a rail height 122 above the base portion 112 of the container 22 in a vertical direction 76, wherein each of the base comb gaps One of the proximal ends 124 of 118 (ie, the "bottom" of the gap 118) defines a gap offset 126 relative to the base portion 112 that is less than the rail height 122 (Fig. 11), and wherein each of the base combs The distal end 128 of the tab 114 relative to one of the base portions 112 defines a protrusion height 132 that is greater than the rail height 122.

Functionally, since the rail height 122 is greater than the gap offset relative to the base portion 112 126, therefore, one of the membrane frames 40 inserted into the base comb 112 will rest on the alignment rail 116. This can eliminate some of the stress on the substrate comb 110 and achieve a more accurate alignment of the film holder 40 within one of the film holder conveyors 20.

In some embodiments, at least one side comb structure 140 is disposed on a side portion 32 of the container 22, the side comb structure 140 including a plurality of side comb protrusions 142 that extend in a vertical direction 76 into the interior chamber 26. The side comb structure 140 includes a plurality of side comb protrusions 144 spaced apart from one another to define a plurality of side comb gaps 148. Adjacent ones of the side comb projections 144 are adapted to engage and receive the outer edge 44 of the membrane frame 40, each side comb gap being defined between adjacent side comb projections of the side comb structure.

The side comb-like gaps are adapted to engage the outer edge 44 of the membrane frame 40 to limit movement of the outer edge 44 in the fore-and-aft direction 56. In addition, each of the alignment slots 62 of the spring holder pads 36 is aligned with a respective one of the side comb gaps 148. In one embodiment, at least a portion of the side comb projections 144 comprise a tapered profile as depicted in FIG. 6A.

In various embodiments, and referring to FIG. 8, each of the first comb gap 78 and the second comb gap 88 define a gap depth 152 having a proximal end 154. Each of the first comb-like protrusions 74 and the second comb-like protrusions 84 in the vertical direction 76 from the proximal end 154 of one of the first comb-shaped gaps 78 and the second comb-shaped gaps 88 One of the first comb-like projections 74/second comb-like projections 84, one of the adjacent distal ends 158, defines a projection height 156. Each of the alignment slots 62 defines a slot depth 162 in a vertical direction 76 relative to one of the main pads 58 toward the upper surface 164.

In various embodiments, the ratio of the protrusion height 152 to the slot depth 162 is between 1.5 and 5 and includes one of 1.5 and 5. In certain embodiments, the ratio is between 2 and 4 and comprises one of 2 and 4. In some embodiments, the ratio is between 2.5 and 3.5 and includes 2.5 and 3.5. One of the ranges. (In the present text, a range of "inclusive" includes the endpoint values of the stated ranges.) In all such embodiments, the first comb-like projections 74 and the second comb-like projections 84 Both are greater than the slot depth 162.

Functionally, the fact that both the first comb-like projection 74 and the second comb-like projection 84 are greater than the slot depth 162 helps prevent or resist "jumping" of the membrane holder 40 during an impact event. The figures provided herein illustrate the spring frame pad 36 in an undeflected state; after being loaded with a film frame 40, the main pad 58 will deflect such that one of the bottoms of the slot 166 is at the same height as the proximal end 154. Thus, if the film holder 40 "jumps" the alignment slot 62, the greater height of the projections 78, 88 will prevent the outer edge 44 of the film holder 40 and redirect the film holder 40 back into the alignment slot 62.

Referring again to FIG. 6A, in one embodiment, at least a portion of the first comb gap 78 and the second comb gap 88 each define a minimum gap dimension 172 in the front-rear direction 56. The minimum gap size 172 can be sized for a tight sliding fit with the membrane frame 40. In certain embodiments, the minimum gap size 172 is between 0.05 inches and 0.085 inches and comprises 0.05 inches and 0.085 inches. In certain embodiments, the minimum gap size 172 is between 0.055 inches and 0.075 inches and comprises 0.055 inches and 0.075 inches. In certain embodiments, the minimum gap size 172 is between 0.055 inches and 0.065 inches and comprises 0.055 inches and 0.065 inches.

Functionally, the tighter tolerance of the minimum gap dimension 172 relative to the outer edge 44 of the membrane frame 40, the tighter the retention of the membrane frame 40, thereby reducing the movement of the membrane frame 40 in the fore-and-aft direction 56, which reduces The role of particle production. At the same time, the slots 62 can be kept too large to accommodate easy alignment during loading and realignment during an impact event.

In various embodiments, the spring carrier pad 36 is mounted in a press fit It is detachable from the film frame transport device 20 into the slotted rail 38.

Referring to Fig. 12, a first spring holder 36 is disposed on the cover and a second spring holder 36 is disposed on the container.

Referring to Fig. 13, a third spring holder 36 is disposed on the container.

In various embodiments, and referring again to Figures 6 and 7, the spring carrier pad 32 includes a continuous frame 182. The continuous frame 182 includes four sides to define four corners 184. For the spring frame pad 36b, the first comb structure 72 and the second comb structure 82 include protrusions 186 that extend around the four corners 184.

22‧‧‧ Container

24‧‧‧ Cover

28‧‧‧Model base

Claims (34)

A film frame shipper comprising: a container; a cover for forming a closure on the container portion to define an interior chamber; a spring frame cushion coupled to the container and At least one of the covers, the spring holder includes an opposite side extending in a fore/aft direction and supporting a main pad portion, the main pad portion defining a plurality of alignment slots, each of the alignment slots Extending in a lateral direction orthogonal to the front-rear direction and adapted to engage an outer edge of a film frame to restrict movement of the film frame in the front-rear direction; and a first comb structure including plural First first comb-like protrusions extending from a first one of the opposite sides of the spring holder pad in a vertical direction, the first comb-like protrusions being spaced apart from each other Enclosing a plurality of first comb-shaped gaps orthogonal to the front-rear direction and orthogonal to the transverse direction; wherein adjacent ones of the first comb-like projections are adapted to engage and receive the film The outer edge of the frame, and each of the first combs a gap between the adjacent ones of the first comb-like protrusions of the first comb-like structure, each of the first comb-shaped gaps being adapted to catch the outer edge of the film holder to limit the outer Movement of the edge in the front-rear direction; and wherein each of the alignment slots is aligned with the one of the first comb-shaped gaps in the lateral direction. The film frame conveying device of claim 1, comprising: a second comb structure comprising a plurality of second comb protrusions, the second comb protrusions from the opposite sides of the spring frame pad One of the second ones extends in the vertical direction, the second comb-like protrusions are spaced apart from each other to define a plurality of second comb-shaped gaps; wherein the second comb-like protrusions are adjacent to the second combs The protrusions are adapted to engage and Receiving the outer edge of the film holder, and one of the second comb-shaped gaps is defined between the adjacent second comb-shaped protrusions of the second comb-shaped structure, the first a comb-like gap adapted to catch the outer edge of the film holder to limit movement of the outer edge in the front-rear direction, and wherein each of the alignment slots is along the lateral direction and one of the second comb-shaped gaps The corresponding ones are aligned. The film frame transfer device of claim 1, wherein the main pad portion defines a plurality of through-slots, each of the through slots being disposed in adjacent aligned slots of the aligned slots between. The film frame conveying device according to any one of claims 1 to 3, comprising: at least one base comb structure disposed on a base portion of the container, the base comb structure comprising a plurality of base comb protrusions The base comb-like projections extend from the base portion of the container in the vertical direction into the interior chamber, the base comb structure comprising a plurality of base comb-like projections spaced apart from one another to define a plurality of base combs a gap; wherein adjacent ones of the base comb projections are adapted to engage and receive the outer edge of the film holder, each of the base comb gaps being defined adjacent to the base comb projections The base comb gaps are adapted to catch the outer edge of the film holder to limit movement of the outer edge in the front-rear direction; and wherein each of the alignment slots of the spring holder pad and the substrate One of the comb gaps is aligned with the plane. The film frame transfer device of claim 4, comprising a registration rail extending from the base portion and extending in the front-rear direction, the alignment rail being defined above the base portion of the container along the vertical direction a rail height, wherein a proximal end of each of the base comb gaps defines a gap offset relative to the base portion, the gap offset being less than the rail height, and wherein each The distal end of the base comb projection relative to one of the base portions defines a protrusion height that is greater than one of the rail heights. The film frame conveying device of claim 4, comprising: at least one side comb structure disposed on a side of the container, the side comb structure comprising a plurality of portions extending in the vertical direction into the inner chamber a side comb-like protrusion comprising a plurality of side comb-like protrusions spaced apart from each other to define a plurality of side comb-like gaps; wherein adjacent ones of the side comb-like protrusions are adapted to engage and receive The outer edge of the film frame, each of the side comb-like gaps is defined between adjacent ones of the side comb-like protrusions, each of the side comb-shaped gaps being adapted to catch the outer edge of the film frame, To limit movement of the outer edge in the front-rear direction; and wherein each of the alignment slots of the spring holder pad is aligned with a respective one of the side comb-like gaps. The film frame conveying device of claim 6, wherein the first comb-like projections, the second comb-like projections, the base comb-like projections, and/or the side comb-like projections are At least a portion of each includes a proximal end and a distal end defining a tapered profile extending in the lateral direction, the tapered profile being symmetrical about an axis extending along the vertical direction, the tapered profile being from the proximal The end to the distal end is inclined toward the axis of the projection. The film holder transfer device of claim 7, wherein at least a portion of the tapered profile is arched. The film frame conveying device of claim 7, wherein: each of the first comb-shaped gaps defines a gap depth of a proximal end; each of the first comb-shaped protrusions from the first comb along the vertical direction a proximal end of one of the adjacent gaps to a distal end of one of the first comb-like protrusions defining a protrusion height; Each of the alignment slots defines a slot depth in the vertical direction relative to the one of the main pads toward the top; and the ratio of the protrusion height to the slot depth is between 1.5 and 5 and includes one of 1.5 and 5 Inside. The film frame transfer device of claim 9, wherein the ratio is between 2 and 4 and comprises one of 2 and 4. The film frame transfer device of claim 10, wherein the ratio is between 2.5 and 3.5 and comprises one of 2.5 and 3.5. The film frame transport device of claim 6, wherein the first comb gap, the second comb gap, the base comb gap, and/or at least a portion of the side comb gaps are each along The front and rear direction defines a minimum gap dimension that is sized for achieving a tight sliding fit with the film frame. The film holder transfer device of claim 12, wherein the minimum gap size is between 0.05 inches and 0.085 inches and comprises 0.05 inches and 0.085 inches. The film holder transfer device of claim 13, wherein the minimum gap size is between 0.055 inches and 0.075 inches and comprises 0.055 inches and 0.075 inches. The film holder transfer device of claim 14, wherein the minimum gap size is between 0.055 inches and 0.065 inches and comprises 0.055 inches and 0.065 inches. The film holder transfer device of claim 1, wherein the at least one spring holder pad is detachable from the film holder transfer device. The film frame transfer device of claim 1 or claim 16, wherein the at least one spring holder pad comprises a first spring holder pad disposed on the cover and a second spring holder pad disposed on the container. The film frame transfer device of claim 17, wherein the at least one spring holder pad comprises One of the third spring holder pads on the container. The film holder conveying device of claim 1, comprising at least one film holder disposed therein. A spring holder pad for coupling to a film holder transporting device, the spring holder pad comprising: an opposite side extending in a front-rear direction and supporting a main pad portion, the main pad portion defining a plurality of alignment slots, each of the Aligning the slot extending in a lateral direction orthogonal to the front-rear direction and adapted to catch an outer edge of a film frame to restrict movement of the outer edge in the front-rear direction; and a first comb structure including plural First first comb-like protrusions extending from a first one of the opposite sides of the spring holder pad in a vertical direction and spaced apart from each other to define a plurality of first combs a vertical gap orthogonal to the front-rear direction and orthogonal to the transverse direction; wherein adjacent ones of the first comb-like projections are adapted to engage and receive the outer edge of the film holder, and each The first comb gaps are defined between adjacent ones of the first comb protrusions of the first comb structure, and each of the first comb gaps is adapted to catch the outer side of the film frame An edge to limit movement of the outer edge in the front-rear direction; and Each respective one of the aligned slots aligned in one direction such that the lateral gap wherein the first comb. The spring shelf pad of claim 20, comprising: a second comb structure comprising a plurality of second comb protrusions, wherein the second comb protrusions are from the opposite sides of the spring holder pad a second one extending in the vertical direction, the second comb-like protrusions being spaced apart from each other to define a plurality of second comb-shaped gaps; wherein adjacent ones of the second comb-shaped protrusions are adapted to engage And receiving the outer edge of the film frame, and each of the second comb gaps is defined between adjacent ones of the second comb protrusions of the second comb structure, each of the second combs a gap adapted to catch the outer edge of the membrane frame to limit movement of the outer edge in the front-rear direction; Each of the alignment slots is aligned with the corresponding one of the second comb gaps in the lateral direction. The spring shelf pad of claim 20, wherein the primary pad portion defines a plurality of through slots, each of the through slots being disposed between adjacent alignment slots of the aligned slots. The spring carrier pad of claim 20, wherein at least a portion of the first comb-like projections each include a proximal end and a distal end and define a tapered profile extending in the lateral direction, the tapered profile Regarding the axis symmetry about one of the projections extending in the vertical direction, the tapered profile is inclined from the proximal end to the distal end toward the projection axis. The spring carrier pad of claim 23, wherein at least a portion of the tapered profile is arcuate. The spring shelf pad of claim 23, wherein: each of the first comb-shaped gaps defines a gap depth of a proximal end; each of the first comb-shaped protrusions from the first comb shape along the vertical direction a distal end of one of the adjacent ones of the gaps to a distal end of one of the first comb-like protrusions defining a protrusion height; each of the alignment slots being relative to the vertical direction One of the main pads defines a slot depth toward the top; and the ratio of the protrusion height to the slot depth is between 1.5 and 5 and includes one of 1.5 and 5. The spring carrier pad of claim 25, wherein the ratio is between 2 and 4 and comprises one of 2 and 4. The spring carrier pad of claim 26, wherein the ratio is between 2.5 and 3.5 and comprises one of 2.5 and 3.5. The spring carrier pad of claim 20, wherein at least a portion of the first comb gaps are each A minimum gap dimension is defined along the fore and aft direction, the minimum gap dimension being sized for achieving a tight sliding fit with the membrane frame. The spring shelf pad of claim 28, wherein the minimum gap size is between 0.05 inches and 0.085 inches and comprises 0.05 inches and 0.085 inches. The spring carrier pad of claim 29, wherein the minimum gap size is between 0.055 inches and 0.075 inches and comprises 0.055 inches and 0.075 inches. The spring shelf pad of claim 30, wherein the minimum gap size is between 0.055 inches and 0.065 inches and comprises 0.055 inches and 0.065 inches. The spring carrier pad of claim 20, wherein the opposite sides are part of a continuous frame. The spring carrier pad of claim 32, wherein the continuous frame comprises four sides to define four corners. The spring carrier pad of claim 33, wherein the first comb structure includes a protrusion extending around both of the four corners.