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
  • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
  • H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
  • H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
  • H05K3/3405—Edge mounted components, e.g. terminals
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
  • H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
  • H01L2224/10—Bump connectors; Manufacturing methods related thereto
  • H01L2224/15—Structure, shape, material or disposition of the bump connectors after the connecting process
  • H01L2224/16—Structure, shape, material or disposition of the bump connectors after the connecting process of an individual bump connector
  • H01L2224/161—Disposition
  • H01L2224/16151—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
  • H01L2224/16221—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
  • H01L2224/16225—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/19—Details of hybrid assemblies other than the semiconductor or other solid state devices to be connected
  • H01L2924/191—Disposition
  • H01L2924/19101—Disposition of discrete passive components
  • H01L2924/19105—Disposition of discrete passive components in a side-by-side arrangement on a common die mounting substrate
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
  • H01L2924/19—Details of hybrid assemblies other than the semiconductor or other solid state devices to be connected
  • H01L2924/191—Disposition
  • H01L2924/19101—Disposition of discrete passive components
  • H01L2924/19106—Disposition of discrete passive components in a mirrored arrangement on two different side of a common die mounting substrate
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
  • H01R12/00—Structural associations of a plurality of mutually-insulated electrical connecting elements, specially adapted for printed circuits, e.g. printed circuit boards [PCB], flat or ribbon cables, or like generally planar structures, e.g. terminal strips, terminal blocks; Coupling devices specially adapted for printed circuits, flat or ribbon cables, or like generally planar structures; Terminals specially adapted for contact with, or insertion into, printed circuits, flat or ribbon cables, or like generally planar structures
  • H01R12/50—Fixed connections
  • H01R12/51—Fixed connections for rigid printed circuits or like structures
  • H01R12/55—Fixed connections for rigid printed circuits or like structures characterised by the terminals
  • H01R12/57—Fixed connections for rigid printed circuits or like structures characterised by the terminals surface mounting terminals
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
  • H01R4/00—Electrically-conductive connections between two or more conductive members in direct contact, i.e. touching one another; Means for effecting or maintaining such contact; Electrically-conductive connections having two or more spaced connecting locations for conductors and using contact members penetrating insulation
  • H01R4/02—Soldered or welded connections
  • H01R4/027—Soldered or welded connections comprising means for positioning or holding the parts to be soldered or welded
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01R—ELECTRICALLY-CONDUCTIVE CONNECTIONS; STRUCTURAL ASSOCIATIONS OF A PLURALITY OF MUTUALLY-INSULATED ELECTRICAL CONNECTING ELEMENTS; COUPLING DEVICES; CURRENT COLLECTORS
  • H01R43/00—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors
  • H01R43/02—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors for soldered or welded connections
  • H01R43/0263—Apparatus or processes specially adapted for manufacturing, assembling, maintaining, or repairing of line connectors or current collectors or for joining electric conductors for soldered or welded connections for positioning or holding parts during soldering or welding process
• • 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
  • H05K2201/10—Details of components or other objects attached to or integrated in a printed circuit board
  • H05K2201/10227—Other objects, e.g. metallic pieces
  • H05K2201/1034—Edge terminals, i.e. separate pieces of metal attached to the edge of the PCB
• • 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
  • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
  • H05K3/303—Surface mounted components, e.g. affixing before soldering, aligning means, spacing means
  • H05K3/305—Affixing by adhesive
• • 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
  • H05K3/30—Assembling printed circuits with electric components, e.g. with resistor
  • H05K3/32—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits
  • H05K3/34—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by soldering
  • H05K3/341—Surface mounted components
  • H05K3/3421—Leaded components

Definitions

• This invention relates to an electronic assembly comprising a carrier for electronic components, leads for external connection and interconnections including solder joints for joining the carrier to the leads.
• the invention further relates to a method for manufacturing such an assembly.
• Electronic assemblies of the above kind are often manufactured in a process including reflow soldering. During the process, the assemblies are heated and the solder joints are partly or totally remelted which may cause them to be permanently disconnected.
• the reflow step can be hazardous, not only to individual connections but also to the assembly structure as such.
• surface-mount subassemblies supported by leads are exposed to the risk of total collapse if the joints between the leads and the component carrier are heated to an extent exceeding the limit of their mechanical stability. Said subassemblies are often submitted to more than one reflow process when its motherboard is built up with more subassemblies and components in subsequent steps.
• solder of a higher melting point for the leadframe joints and solder of a lower melting point for the subsequent reflow process It is, however, hard to find solders that have sufficiently high melting temperature without being disqualified by other properties such as brittleness, high cost, content of dangerous substances etc.
• solders that have sufficiently high melting temperature without being disqualified by other properties such as brittleness, high cost, content of dangerous substances etc.
• Another possibility would be to use a brazing material but again the high temperature needed, more than 450* C, will damage many components and even the carrier itself.
• an electrically conductive adhesive as a substitute for solder but this solution is not possible when there is a demand for high electrical efficiency.
• soldering method in US 5,155,904 a soldering method is described that include a step of gluing and reflow soldering components on one side of a printed circuit board before components are installed on the other side. Adhesive dots are placed on the board to attach the component bodies and secure their positions when the board is inverted and the following reflow soldering and wave soldering steps are effected.
• the method is similar to the idea of overmoulding with epoxy above and would bring additional process steps and is not suitable for all assemblies in particular not subassemblies that have many components on one carrier.
• the main object of the present invention is to provide an electronic assembly that has leads mounted to the component carrier with interconnections reliable to withstand one or more reheating periods without loosing conducting or mechanical properties.
• the object includes a method of manufacturing such an electronic assembly. Another objective is to achieve such an electronic assembly and method that are particularly adapted to self-supporting surface mount subassemblies. Still another object is to provide an electronic assembly and a method for its manufacturing that do not add cost or complexity as compared to known solutions.
• these objects of the present invention are accomplished by an electronic assembly and a method of manufacturing such an assembly in which a carrier for electronic components and leads for external connection are connected with each other by interconnections including solder joints. In order to sustain heating periods, at least one of said interconnections comprises an adhesive joint in addition to the solder joint applied between the carrier and one lead.
• An advantage of the present invention is that it enables electronic assemblies of various kinds to get secure interconnections between the carrier and the leads for many different solder materials including non-lead (Pb) ones.
• assemblies can be provided with combined solder and adhesive joints independent of the mutual position of the carrier and leadframe.
• a further advantage is that the assemblies will remain mechanically intact during all normal reflow processes.
• the adhesive may be cured in the same process step as the solder reflow is performed.
• self- supporting surface mount sub-assemblies like power supply modules may adapt the invention without any substantial changes of design and structure and very small changes of the manufacturing steps as compared to a pure solder joint principle.
• Fig. 1 is a side view of an electronic assembly according to the invention
• Fig. 2 is a side view of an alternative assembly according to the invention
• Fig. 3 is a side view of an interconnection between a carrier and leads included in the assembly disclosed in Fig. 1
• Fig. 4 is a side view of a solder spot and an adhesive spot of the interconnection disclosed in Fig. 3 and
• Fig. 5 is a view from above of the spots according to Fig. 4.
• the electronic assembly 11 disclosed in Fig. 1 is a subassembly arranged to be mounted on a motherboard 12 together with various kinds of other electronic details (not shown).
• the subassembly comprises a carrier 13 for a number of electronic components 14 that can be mounted on the top side 15 or bottom side 16 or on both sides of the carrier as shown in Fig. 1.
• the carrier is normally a substrate plate on which an integrated circuit is constructed or attached.
• the subassembly is in a traditional way self-supported by means of a leadframe 17 comprising one or more individual leads 18.
• the basic function of the leads is as usual to be the electrical contact between the subassembly and the motherboard 12.
• the leadframe and leads may have many different designs but one common feature is that at least one lead 18 is electrically connected to at least one circuit and component on the carrier by an interconnection 19 arranged between the carrier and an end part 20 of the lead.
• the subassembly may in the usual way comprise both leads that are electrically connected to the carrier and blind leads that have no such connections. All leads are, however, preferably mounted to the carrier with the same type of interconnection. Said interconnection should not only have the necessary electrical conductivity but also a mechanical strength to withstand the weight of the carrier and all possible external forces caused by movements, temperature etc. These properties are achieved by a combined solder and adhesive joint 21 comprising a solder joint 22 and an adhesive joint 23 as appears from Figs. 3-5.
• the joints 22, 23 can be arranged in many ways and have different configurations but preferably the combined joint 21 is formed by one spot 24 of solder and one spot 25 of adhesive applied side by side with substantially equal areas.
• the spots are applied on a common pad 26 attached to the ca ⁇ ier. It is also possible, however, to apply one or both spots on the lead depending on the design of the assembly.
• the carrier is arranged in a hanging position under the lead end part 20 extending from the motherboard, which courses high tensile stress on the interconnection but the advantage of a compact assembly.
• the carrier is carried on the same free end 20 of the leads but is located in total above the leads. This configuration gives less tensile stress but demands more vertical space. Independent of the chosen design all interconnections have to be reliable enough to withstand all normal reflow processes.
• the manufacture of a subassembly according to the invention include the step of applying solder and adhesive to the spots chosen on the carrier and/or leads.
• the solder is selected to be an alloy with a melting point lower than 450°C.
• the leads are preferably in the form of a united structure or leadframe that may be the final structure with all individual leads configured or a semi-finished structure that later is to be under cutting and bending operations in order to form the individual leads to the desired shape.
• suitable conventional methods for applying solder and adhesive such as screen printing, stencil printing and dispensing. After the application of adhesive and solder, the leadframe and the carrier are attached to each other in a suitable fixture for further processing.
• the adhesive preferably a curable glue
• the adhesive may be cured by means of heat, UV radiation or any other convenient curing process but, since at least one reflow process is included in the manufacture of the subassembly, it is an advantage to combine curing of a heat curable glue with the reflow step.
• the subassembly When all manufacturing steps are finished, the subassembly is ready for installation on the motherboard. During that process the subassembly is normally again reheated and at least part of the motherboard is submitted to one or more reflow processes. The solder in the solder joints will then soften or melt to a liquid state, but the cured adhesive will keep its adhering properties and maintain the interconnections intact.

Landscapes

• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Electric Connection Of Electric Components To Printed Circuits (AREA)
• Wire Bonding (AREA)
• Fixed Capacitors And Capacitor Manufacturing Machines (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=20286434

Family Applications (1)

Country Status (6)

Cited By (3)

Citations (5)

• 2001
  • 2001-12-19 SE SE0104335A patent/SE0104335D0/xx unknown
• 2002
  • 2002-04-24 TW TW091108427A patent/TW540264B/zh not_active IP Right Cessation
  • 2002-12-19 AU AU2002359207A patent/AU2002359207A1/en not_active Abandoned
  • 2002-12-19 WO PCT/SE2002/002429 patent/WO2003053115A1/en not_active Application Discontinuation
  • 2002-12-19 EP EP02793728A patent/EP1459610A1/en not_active Withdrawn
  • 2002-12-19 CN CNA028258517A patent/CN1608397A/zh active Pending

Patent Citations (5)

Non-Patent Citations (1)

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