Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K3/00—Apparatus or processes for manufacturing printed circuits
  • H05K3/0011—Working of insulating substrates or insulating layers
  • H05K3/0044—Mechanical working of the substrate, e.g. drilling or punching
  • H05K3/0052—Depaneling, i.e. dividing a panel into circuit boards; Working of the edges of circuit boards
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/09—Shape and layout
  • H05K2201/09009—Substrate related
  • H05K2201/09036—Recesses or grooves in insulating substrate
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/09—Shape and layout
  • H05K2201/09009—Substrate related
  • H05K2201/09063—Holes or slots in insulating substrate not used for electrical connections
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/09—Shape and layout
  • H05K2201/09009—Substrate related
  • H05K2201/0909—Preformed cutting or breaking line
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
  • H05K2201/00—Indexing scheme relating to printed circuits covered by H05K1/00
  • H05K2201/09—Shape and layout
  • H05K2201/09818—Shape or layout details not covered by a single group of H05K2201/09009 - H05K2201/09809
  • H05K2201/09827—Tapered, e.g. tapered hole, via or groove

Definitions

• the present invention relates to circuit board manufacturing and more particularly, to assembly-line processes in the circuit board manufacturing.
• panels that consist of multiple (usually three) boards, are widely used in manufacturing lines. These panels are routed along the boundaries of each board except for a few connecting points (called breakaways) to fit into a housing profile. After components are placed and reflowed, populated boards are to be singulated or depanelized by breaking or cleaving these breakaways. Depanelization is often performed manually by operators. Nearby conducting circuit lines or connecting pads on boards may, however, be torn off or delaminated when breakage does not cleave cleanly (402; 502) through the thickness of the breakaways (FIG. 4 and FIG. 5, numerals 400 and 500, respectively).
• FIG. 2 shows a typical single perforated breakaway design as is known in the art.
• perforations provide breakaway joints (202) that allow depanelization of the circuit board panel (204).
• FIG. 3 shows a typical double perforated breakaway design as is known in the art.
• two rows of perforations (302) provide breakaway joints that allow depanelization of the circuit board panel (304), with the circuit board between the two rows being waste (306).
• the first method utilizes 'H' shaped breakaway connections (104) with cutouts (106) that extend completely through the whole board thickness (see FIG. 1 , numeral 100), with throwaway strips (108) along two opposing outermost edges of the circuit board panel. Breakaway joints present a weak link to allow easy depanelization. This method does not. however, prevent board delamination/tear-off. In addition, the punched routing weakens the panel to such a large extent that the panel sags substantially on the conveyor, interfering with correct placement of electrical components on the circuit boards (102). The second method applies v- grooves to a line along which the panel will be broken.
• v-grooves have been used for a long time for products such as a PC (personal computer) mother board, PCMCIA cards (Personal Computer Memory Card Industry Association cards), etc.
• v-grooves cannot be used for printed circuit boards where the board boundary profile is not straight-lined.
• v-grooves are not suitable where non-straight-lined boards are implemented for cellular products with zig-zagged or curved board boundaries that are employed for housing assembly and real estate considerations. More ver, using thin circuit boards for complex circuit board manufacturing augments the sagging problem.
• FIG. 6, numeral 600 shows a schematic of a prior art circuit board that is sagging (602) due to the fact that the breakaway joints present a weak link that induces a large displacement in the middle of the board panel during manufacturing.
• FIG. 1 shows a typical ⁇ ' shaped breakaway design as is known in the art.
• FIG. 2 shows a typical single perforated breakaway design as is known in the art.
• FIG. 3 shows a typical double perforated breakaway design as is known in the art.
• FIG. 4 is a schematic representation of tearing/delamination that typically occurs due to the fact that a crack tip encounters a compressive stress state upon using the "H" shaped breakaway design of FIG. 1.
• FIG. 5 is a schematic representation of unsymmetric crack initiation due to the mixture of tensile and shear stress states, increasing potential for curved fracture path that also typically occurs upon using the "H" shaped breakaway design of FIG. 1.
• FIG. 6 shows a schematic of a prior art circuit board that is sagging due to the fact that the breakaway joints present a weak link that induces a large displacement in the middle of the complex circuit board panel during manufacturing.
• FIG. 7 is a schematic representation of a circuit board panel after v-grooves have been implemented in the second step for substantially eliminating assembly-line delamination and sagging for circuit board manufacturing as is set forth in U.S. Patent Application Serial No. 08/672,736, filed June 28, 1 996.
• FIG. 8 is a schematic representation of one embodiment of a circuit board panel with channels/gouges for substantially eliminating assembly-line delamination and sagging for complex circuit board manufacturing in accordance with the present invention.
• FIG. 9 is a schematic representation of a second embodiment of a circuit board panel with two sets of substantially parallel channels/gouges for substantially eliminating assembly-line delamination and sagging for complex circuit board manufacturing in accordance with the present invention.
• FIG. 10 is a schematic representation of a third embodiment of a circuit board panel with channels/gouges for substantially eliminating assembly-line delamination and sagging for complex circuit board manufacturing in accordance with the present invention.
• FIG. 11 is a flow chart of one embodiment of steps of a method for substantially eliminating assembly-line delamination and sagging for complex circuit board manufacturing.
• the present invention provides robust stiffness for circuit board panels during manufacturing to minimize sagging, while concurrently providing depanelization joints that minimize delamination of manufactured printed circuit boards.
• the invention while minimizing sag of the whole panel, more importantly minimizes the amount of force required to break the extra board waste of the panel away from the circuit boards.
• the invention also minimizes the amount of force needed to break the circuit board away from the other circuit boards or panel. This action of "breaking" is usually done manually, without aid of mechanical tools, in order not to damage the components or components solder joints on the circuit boards. Also, if the panel is placed in a holding device whose outer edge is positioned to facilitate breaking along the depanelization joints, the present invention aids aids in depanelization.
• the invention allows the circuit boards to be broken in such a way that as soon as a "crack" is introduced inside the channel/gouge, this crack propagates at a much, much faster rate than the prior art, so that the force to break the circuit board off the panel is reduced.
• the present invention provides a cleaner, more defined edge, which results in a better breaking edge to utilize when placing complex components in the circuit board design.
• This invention allows the circuit board designer to utilize the circuit board surface area more efficiently. That is, the invention gives the circuit designer more real estate or circuit board area on which to place complex components. Also, the invention allows the circuit boards to be separated from the panels without the use of expensive machinery.
• complex means that the state or design of circuit boards utilizes minute components such as: resistors, capacitors, inductors, transistors, etc., where the mentioned components are placed on the circuit boards using high speed automatic robotic assembly methods.
• FIG. 7, numeral 700 is a schematic representation of a circuit board panel after v-grooves have been implemented in the second step for substantially eliminating assembly-line delamination and sagging for circuit board manufacturing as is set forth in U.S. Patent Application Serial No. 08/672,736.
• Circuit boards (702) are typically populated with the complex components such as: resistors, capacitors, inductors, transistors, etc. Each circuit board will then be placed inside the designed housing of a product, for example, a cellular phone.
• notches or cutouts are designed into the panel for each circuit board as a clearance for a feature inside a product housing that fits into the notch/cutout.
• the notch/cutout is generally designed to clear other components on another circuit board that will be placed inside the same housing of the product.
• a channel/gouge 706 is cut into the top side of the panel for an edge of a circuit board such that the channel/gouge provides the location where the complex circuit board will be removed/separated from the intitial state of being a part of the panel.
• a channel/gouge (708) is cut on the bottom side of the panel that provides the location where the complex circuit board will be removed/separated from the original panel. This action of removal/separation is described as depanelization.
• FIG. 8, numeral 800 is a schematic representation of one embodiment of a circuit board panel with channels/gouges for substantially eliminating assembly-line delamination and sagging for complex circuit board manufacturing in accordance with the present invention.
• circuit boards (802) of the circuit board panel are populated with complex components such as: resistors, capacitors, inductors, transistors, etc., during a manufacturing process wherein outermost edges (804) of outermost circuit boards are supported as the circuit board panel passes down a manufacturing line. After depanelization, the circuit boards will then be placed inside the designed housings of the products.
• apertures (806) are designed into the circuit board as a clearance for a feature inside the housing that will fit into the apertures.
• the apertures may have various selected shapes (814) and may also be designed to clear other components on another circuit board that will be placed inside the same housing of the product.
• a channel/gouge (808) is cut into the top side of the panel that provides the location where the complex circuit board will be removed/separated from the intitial state of being a part of the panel.
• a channel/gouge (810) is also cut into the bottom side of the panel, not directly beneath the channel/gouge of the top side of the panel, but instead situated at an offset position that provides the location such that the channel/gouge on the top and the channel/gouge on the bottom have predetermined depths and a predetermined distance "d" between the deepest portion of the top and bottom channels/gouges. The depth and positioning of the channels/gouges is described further below.
• a workable depth range for each of the top and bottom channels/gouges which are v-grooves is 3-10 mils
• a horizontal distance range between the centers of the v-grooves is 2-3 mils
• d (812) is determined as a hypotenuse of the selected values.
• the depths of the v- grooves may be selected to be the same or to be different.
• a depth of 10 mils for each of the top and bottom v-grooves and a horizontal distance "a" of 3 mils provide a workable "d” distance (see formula below).
• the circuit board panel includes a plurality of circuit board modules having printed circuit boards arranged in parallel wherein each module includes: A) a plurality of apertures (804) along a circuit board profile; and B) a channel/gouge on a top of the circuit board and another channel/gouge on a bottom of the circuit board along the circuit board profile through the apertures (806) in accordance with a break-away scheme where the channel/gouges are positioned at a predetermined horizontal critical distance apart with a predetermined vertical critical distance between a deepest cut edge of the channel/gouge on the top of the circuit board and a deepest cut edge of the channel/gouge on the bottom of the circuit board.
• the predetermined scheme for a total length of the channels/gouges is determined in accordance with a preselected scheme: either channels/gouges are cut an entire length of each circuit board, i.e., the channels/gouges are cut substantially an entire width of the circuit board panel (for example, as shown in FIG. 8), or, alternatively, the channels/gouges are cut across apertures (see FIG. 10) or other channels/gouges that separate the circuit boards, such that the channels/gouges are cut substantially an entire length of the circuit board panel.
• the depth of the channel/gouge is typically determined by:
• a represents a dimensionless constant from 0.3 to 0.6 determined by a simulation
• P represents a weight of a circuit board panel containing a predetermined number of circuit boards
• W represents a width of the circuit board
• E represents a modulus of material for the circuit board
• L represents a total length of the circuit board profile
• ⁇ c represents a predetermined manufacturing tolerance for sagging.
• H C represents a depth of the v-groove.
• the v-grooves are generally cut in accordance with an angle determined by an equation of the form:
• v-grooves where represents a cutting angle for the v-groove, w c represents a distance across a widest opening of the v- grooves, and H C represents a depth of the v-grooves.
• the v-grooves generally have a v angle of 25° to 30°.
• the break-away scheme allows the circuit board to be separated along a length of each circuit board profile.
• the predetermined scheme for a total length of the channels/gouges is a total full length of each circuit board profile, as shown in FIG. 10, numeral 1000.
• the break-away scheme allows the circuit board to be separated along a top edge of each circuit board profile wherein the top edge is located substantially in a direction perpendicular to a lengthwise side of each circuit board profile.
• the v-groove is typically cut in accordance with an angle determined by an equation of the form:
• w c represents a distance across a widest opening of the v-groove
• H C represents a depth of the v-groove
• the depth of the v- groove is determined in accordance with equations of the form:
• M represents a moment about an axis of the v-groove upon depanelization
• H represents a thickness of the circuit board
• H c represents a depth of a- cut of the v-groove
• K i c represents a constant for a toughness of material of the circuit board
• P represents a weight of a circuit board panel containing a predetermined number of circuit boards
• W represents a width of the circuit board
• E represents a modulus of material for the circuit board
• L represents a total length of the circuit board profile
• ⁇ c represents a predetermined manufacturing tolerance for sagging.
• FIG. 9, numeral 900 is a schematic representation of a second embodiment of a circuit board panel with two sets of substantially parallel channels/gouges for substantially eliminating assembly-line delamination and sagging for complex circuit board manufacturing in accordance with the present invention.
• a portion of the printed circuit board panel between the two sets of channels/gouges will be waste (912).
• Each circuit board (902) will typically be populated with the complex components such as: resistors, capacitors, inductors, transistors, etc. during the manufacturing process (as the circuit board panel travels down a manufacturing line). Upon depanelization, each circuit board will then be placed inside a designed housing of a product.
• Apertures (904) are typically designed into the circuit board as a clearance for a feature inside the housing that will fit into the apertures (904). Clearly, the shape of the apertures is selectable. The apertures (904) may also be designed to clear other components on another circuit board that will be placed inside the same housing of the product.
• the channels/gouges on the top side (906) of the panel provide the location where the complex circuit board will be removed/separated from the intitial state of being a part of the panel.
• the channels/gouges on the bottom side (908) of the panel provide the location where the complex circuit board will be removed/separated from the intitial state of being a part of the panel.
• the distance "d" (910) is described more fully above.
• FIG. 10, numeral 1000 is a schematic representation of a third embodiment of a circuit board panel (1002) with channels/gouges for substantially eliminating assembly-line delamination and sagging for complex circuit board manufacturing in accordance with the present invention.
• apertures (1004) separate the circuit boards (1006) that will be populated with the complex components such as: resistors, capacitors, inductors, transistors, etc., and the channels/gouges (1008) traverse the tops and bottoms of the circuit boards instead of the sides of the circuit boards as was done in the previous embodiment.
• the circuit boards will be depaneled and placed inside the designed housing of the product.
• the apertures (1004) that are designed into each circuit board typically provide clearance for a feature inside the housing that will fit into the aperture.
• the aperture generally may also be designed to clear other components on another circuit board that will be placed inside the same housing of the product.
• the channel/gouge (1010) on the top side of the panel provides the location where the complex circuit board will be removed/separated from the intitial state of being a part of the panel.
• the channel/gouge (1012) on the bottom side of the panel provides the location where the complex circuit board will be removed/separated from the intitial state of being a part of the panel.
• the distance "d" (1014) is maintained at a predetermined distance as set forth above in order to conform to funtional manufacturing parameters of complex circuit boards.
• FIG. 11 is a flow chart of one embodiment of steps of a method for substantially eliminating assembly- line delamination and sagging for complex circuit board manufacturing.
• the method of the present invention provides for substantially eliminating assembly-line delamination and sagging for complex circuit board manufacturing.
• the method includes the steps of: A) cutting/routing at least two apertures to fit into a circuit board profile of a circuit board (1102), wherein a total length of the apertures is determined in accordance with a predetermined scheme; and B) cutting/routing a channel/gouge on a top of the circuit board and another channel/gouge on a bottom of the circuit board along the circuit board profile through the apertures in accordance with a break-away scheme where the channel/gouges are positioned at a predetermined horizontal critical distance apart with a predetermined vertical critical distance between a deepest cut edge of the channel/gouge on the top of the circuit board and a deepest cut edge of the channel/gouge on the bottom of the circuit board (1104).
• the predetermined scheme for a total length of the channels/gouges is determined in accordance with a preselected scheme: either channels/gouges are cut an entire length of each circuit board, i.e., the channels/gouges are cut substantially an entire width of the circuit board panel (for example, as shown in FIG. 8), or, alternatively, the channels/gouges are cut across apertures (see FIG. 10) or other channels/gouges that separate the circuit boards, such that the channels/gouges are cut substantially an entire length of the circuit board panel.
• the channel/gouge is a v-groove
• the depth is typically determined as set forth above.
• the break-away scheme allows the circuit board to be separated along a lengthwise side of each circuit board profile.
• the predetermined scheme for a total length of the apertures may be a total full length of each circuit board profile.
• the break-away scheme allows the circuit board to be separated along a top edge of each circuit board profile wherein the top edge is located substantially in a direction perpendicular to a lengthwise side of each circuit board profile.
• the predetermined horizontal critical distance and the predetermined vertical critical distance between an outermost edge of the channel/gouge of the top and the bottom are typically determined as set forth above.
• the channel/gouge is a v-groove
• the channel/gouge is cut in accordance with a depth and an angle as described above.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Structure Of Printed Boards (AREA)

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Publications (1)

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ID=25149896

Family Applications (1)

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Citations (6)

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• 1997
  • 1997-12-19 CN CN 97192718 patent/CN1212820A/zh active Pending
  • 1997-12-19 JP JP10531973A patent/JP2000508838A/ja active Pending
  • 1997-12-19 WO PCT/US1997/023550 patent/WO1998033364A1/en active Application Filing
• 1998
  • 1998-01-15 FR FR9800363A patent/FR2762959B1/fr not_active Expired - Fee Related
  • 1998-01-16 TW TW87100578A patent/TW388193B/zh active

Patent Citations (6)

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