Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L24/00—Arrangements for connecting or disconnecting semiconductor or solid-state bodies; Methods or apparatus related thereto
  • H01L24/80—Methods for connecting semiconductor or other solid state bodies using means for bonding being attached to, or being formed on, the surface to be connected
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L23/00—Details of semiconductor or other solid state devices
  • H01L23/48—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor
  • H01L23/488—Arrangements for conducting electric current to or from the solid state body in operation, e.g. leads, terminal arrangements ; Selection of materials therefor consisting of soldered or bonded constructions
  • H01L23/498—Leads, i.e. metallisations or lead-frames on insulating substrates, e.g. chip carriers
  • H01L23/49811—Additional leads joined to the metallisation on the insulating substrate, e.g. pins, bumps, wires, flat leads
• • 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
  • H05K3/328—Assembling printed circuits with electric components, e.g. with resistor electrically connecting electric components or wires to printed circuits by welding
• • 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
  • H01L2924/01—Chemical elements
  • H01L2924/01006—Carbon [C]
• • 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
  • H01L2924/01—Chemical elements
  • H01L2924/01033—Arsenic [As]
• • 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
  • H01L2924/01—Chemical elements
  • H01L2924/01082—Lead [Pb]
• • 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
  • H01L2924/013—Alloys
  • H01L2924/014—Solder alloys
• • 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
  • H01L2924/15—Details of package parts other than the semiconductor or other solid state devices to be connected
  • H01L2924/151—Die mounting substrate
  • H01L2924/156—Material
  • H01L2924/15786—Material with a principal constituent of the material being a non metallic, non metalloid inorganic material
  • H01L2924/15787—Ceramics, e.g. crystalline carbides, nitrides or oxides

Definitions

• the invention is related to a method of joining leads to substrates, e.g. in the manufacture of subassemblies mounted on a larger circuit board.
• a subassembly here taken as comprising a carrier having a conductive pattern, various components mounted thereto and a leadframe. If the subassembly has the carrier, e.g. a ceramic substrate, located under the leadframe, the weight of the carrier and the components may cause the assembly to collapse and the substrate to fall down. This case is illustrated in Fig. 1.
• the carrier e.g. a ceramic substrate
• Solder is herein taken to mean an alloy having a melting point below 450°C, intended for joining two parts at a temperature below the melting points of these parts.
• a braze is an alloy having a melting point higher than 450 °C and intended for the same use.
• solders in the desired temperature range have disqualifying properties such as brittleness, high cost or that they can contain hazardous substances. Also, many components cannot withstand the elevated temperature needed when using high temperature solders. - The components cannot withstand the high temperature needed for the reflow process of brazing materials.
• holes are made in the leads of the frame and then the leads are welded to the pads.
• the holes reduce the energy required for the welding.
• the holes can preferably cover about 50% of the area heated in the welding process.
• Fig. 1 is a cross-sectional view of a leadframe joined to a substrate
• FIG. 2 is fragmentary plan view of a lead joined to a contact pad.
• a subassembly comprising an e.g. ceramic substrate 1 joined to a leadframe 3 at joining positions 5.
• connection leads or legs 7 of the leadframe are made to be electrically connected to pads 9 of the substrate, see the fragmentary, plan view of Fig. 2.
• the leads 7 have a thickness considerably larger than then thin contact pads 9.
• the leads are welded to the pads using e.g. a laser beam, plasma welding, a microflame, as indicated at 10.
• the pads will hence be more easily heated than the leads due to the difference in heat capacity resulting from the different thicknesses.
• the leads 7 are provided with at least one and preferably two holes 11 covering e.g. about 50% of the area heated in the welding. These holes can have any shape, e.g. being circular as illustrated in the figure.
• a meltdown of the material in the walls of the holes 11 or in the edge regions of the lead at the holes is obtained, the melted material flowing down to be joined with the material of the underlying pad 9.
• the leadframe is heated at regions around the holes and also the substrate, i.e. the pads 9 thereof, the latter heating occurring through the holes 11.
• the holes 11 can have a diameter in the range of about 0.1 - 0.8 mm made in the leadframe material which can have a thickness in the range 0.1 - 1 mm.
• the incoming, heating energy indicated by the arrows 10, has a direction that is approximately perpendicular to the large surface of the components to be welded to each other.

Landscapes

• Engineering & Computer Science (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Computer Hardware Design (AREA)
• Power Engineering (AREA)
• Physics & Mathematics (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Electric Connection Of Electric Components To Printed Circuits (AREA)
• Connections Effected By Soldering, Adhesion, Or Permanent Deformation (AREA)
• Lead Frames For Integrated Circuits (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=20284987

Family Applications (1)

Country Status (6)

Families Citing this family (2)

Family Cites Families (3)

• 2001
  • 2001-08-07 SE SE0102668A patent/SE521528C3/sv not_active IP Right Cessation
  • 2001-08-29 TW TW090121349A patent/TW531462B/zh not_active IP Right Cessation
• 2002
  • 2002-08-07 JP JP2003520257A patent/JP2004538656A/ja active Pending
  • 2002-08-07 WO PCT/SE2002/001434 patent/WO2003015485A1/en active Application Filing
  • 2002-08-07 CN CNB028153472A patent/CN1270376C/zh not_active Expired - Fee Related
  • 2002-08-07 EP EP02756051A patent/EP1415519A1/de not_active Withdrawn

Non-Patent Citations (1)

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