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
  • H05K3/341—Surface mounted components
  • H05K3/3431—Leadless components
  • H05K3/3436—Leadless components having an array of bottom contacts, e.g. pad grid array or ball grid array components
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
  • G01R1/02—General constructional details
  • G01R1/06—Measuring leads; Measuring probes
  • G01R1/067—Measuring probes
  • G01R1/073—Multiple probes
  • G01R1/07307—Multiple probes with individual probe elements, e.g. needles, cantilever beams or bump contacts, fixed in relation to each other, e.g. bed of nails fixture or probe card
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R1/00—Details of instruments or arrangements of the types included in groups G01R5/00 - G01R13/00 and G01R31/00
  • G01R1/02—General constructional details
  • G01R1/06—Measuring leads; Measuring probes
  • G01R1/067—Measuring probes
  • G01R1/06711—Probe needles; Cantilever beams; "Bump" contacts; Replaceable probe pins
  • G01R1/06755—Material aspects
• • G—PHYSICS
  • G01—MEASURING; TESTING
  • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
  • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
  • G01R31/28—Testing of electronic circuits, e.g. by signal tracer
  • G01R31/2851—Testing of integrated circuits [IC]
  • G01R31/2886—Features relating to contacting the IC under test, e.g. probe heads; chucks
• • 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
  • H05K2201/02—Fillers; Particles; Fibers; Reinforcement materials
  • H05K2201/0203—Fillers and particles
  • H05K2201/0206—Materials
  • H05K2201/0215—Metallic fillers
• • 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
  • H05K2201/03—Conductive materials
  • H05K2201/0332—Structure of the conductor
  • H05K2201/0335—Layered conductors or foils
  • H05K2201/035—Paste overlayer, i.e. conductive paste or solder paste over conductive layer
• • 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
  • H05K2201/10613—Details of electrical connections of non-printed components, e.g. special leads
  • H05K2201/10954—Other details of electrical connections
  • H05K2201/10992—Using different connection materials, e.g. different solders, for the same connection
• • 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
  • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
  • H05K2203/03—Metal processing
  • H05K2203/0338—Transferring metal or conductive material other than a circuit pattern, e.g. bump, solder, printed component
• • 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
  • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
  • H05K2203/16—Inspection; Monitoring; Aligning
  • H05K2203/162—Testing a finished product, e.g. heat cycle testing of solder joints
• • 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
  • H05K2203/00—Indexing scheme relating to apparatus or processes for manufacturing printed circuits covered by H05K3/00
  • H05K2203/17—Post-manufacturing processes
  • H05K2203/176—Removing, replacing or disconnecting component; Easily removable component
• • 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
  • H05K3/3457—Solder materials or compositions; Methods of application thereof
  • H05K3/3485—Applying solder paste, slurry or powder
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P70/00—Climate change mitigation technologies in the production process for final industrial or consumer products
  • Y02P70/50—Manufacturing or production processes characterised by the final manufactured product

Definitions

• the present invention relates to a method of testing and fitting electronic components that are to be surface mounted on a circuit board.
• BGA ball grid array components
• flip-chip components examples include on one side thereof solder balls or the like that are to be connected electrically to pads on a test board so as to enable the function of the surface component to be tested subsequent to mounting said components.
• CSP chip scale packages
• BGA component packaging of chips in the form of integrated circuits or multichip modules is a rapidly growing technology. It is anticipated that BGA components will have a significant share of the market in the very near future.
• One problem encountered with BGA components is that the perfor ⁇ mance of said components in operation cannot be tested prior to mounting the components on a printed circuit board, PCB. It is particular difficult to test BGA components at high analog signal frequencies and at high digital signal speeds. The difficulty is actually encountered in achieving good electric contact and other effective electrical conditions between the BGA component and a test board to which the BGA component shall be connected during a test. A few techniques have been proposed in this respect.
• One tech ⁇ nique uses an interposer, which is a layer applied between the BGA component and the test board and electrically conductive in directions perpendicular to the plane of the interposer.
• This may refer to electrically conductive needles that extend perpendicu ⁇ lar to the plane of the interposer between the BGA component and the test board, or anisotropically conductive films.
• a few mounting bases have also recently been developed for connection to the BGA component and to the test board respectively.
• the present invention provides an inexpensive method which requires only a low contact pressure between the BGA component and the test board, which also gives low contact resistances and low parasitic inductances and capacitances.
• the present invention relates to a method of testing and, in certain cases, mounting electronic surface-mounted components which include on one side a plurality of contact pads intended for electrical connection with contact pads on one side of a test board, particularly BGA components and corresponding components, and is characterized by applying to the component contact pads or points a metal that is liquid at room temperature or at an elevated room temperature, in a first method step; by lifting the component from the surface of the liquid metal in a second method step, such that part of the liquid metal remains on the contact points; and by bringing the contact pads provided with said liquid metal into abutment with corresponding contact pads on the test board, in a third method step.
• Figure 1-3 illustrate different steps of the inventive method
• Figure 4 illustrates an embodiment of the invention.
• FIGS 1-3 illustrate the inventive method of testing the performance of electronic components that are to be surface- mounted on a printed circuit board.
• the electronic component exemplified in the Figures is a BGA component 1.
• One side of the BGA component 1 includes a plurality of contact pads 2, which normally consist of about 60% tin and 40% lead. These contact pads 2 are intended for electrical connection with corresponding contact pads 3 on one side of a test board (PCB) 4; see Figure 3.
• PCB test board
• the contact pads 2 on the component 1 are coated in a first method step with a metal 5 that is liquid at room temperature or at elevated room temperatures. This step is illustrated in Figure 2.
• the contact pads 2 are preferably dipped into the liquid metal.
• the metal can be applied to the contact pads by a process corresponding to a pressure process, in which a cylindrical surface containing the liquid metal is rolled over the component surface on which the contact pads are found.
• the liquid metal is contained on a flat surface, such as on a glass plate 6 or a silicon plate.
• the depth of the metal on the plate will prefera ⁇ bly be less than the height of the contact pads 2 on the compo- nent 1, so as to ensure that only the pads 2 will come into contact with the liquid metal 5.
• the contact pads 2 are wetted with the metal in this way.
• the component is lifted from the surface of the liquid metal, as illustrated in Figure 2, wherewith a part 7 of said metal will remain on the contact pads.
• the contact pads 2 provided with said liquid metal 7 are brought into abutment with corre- sponding contact pads 3 on the test board 4, as illustrated in Figure 3, therewith establishing effective electric contact between the contact pads 2 on the component and the corresponding contact pads 3 on the test board.
• the electronic component 1 is then tested.
• the component 1 is lifted and the liquid metal 7 removed from its contact pads 2. It has been found that the metal 7 can be readily removed with water and a conventional detergent.
• the fourth step is optional for the reason made evident hereinafter, although it is not always carried out.
• the liquid metal is gallium (Ga) or a gallium alloy.
• the liquid metal is mercury (Hg) or a mercury compound, although this metal is not equally as well preferred, because of its detriment to the environment.
• Gallium and gallium alloys exist in a liquid phase at room temperature or temperatures slightly above room temperature. They also have low resistivity, namely a resistively of about 14 microOhm x cm. By way of comparison, it can be mentioned that copper has a resistivity of 1.56 microOhm x cm.
• gallium and its alloys are easy to use, and consequently are not hazardous to the health or to the environment hazard, due to their low vapour pressure among other things. Liquid gallium has an extremely low vapour pressure, namely only 10 "10 torr at 400°C. Mercury has a much higher vapour pressure, normally 10 +3 torr at 400°C.
• alloys can also be tailor-made with respect to viscosity, by admixing metal powder with the liquid alloy. Many different metals can be used to this end. Table 1 discloses examples of preferred metals in the right-hand column. It is preferred to admix at most 20% by weight metal powder. Admixture with metal powder can produce a liquid-gallium based paste into which the contact pads are dipped in the aforesaid manner. The thickness of the paste on the plate 6 and the viscosity of the paste deter ⁇ mines the amount of paste that will adhere to the contact pads when s"aid pads are dipped into the paste.
• Table 2 below shows the wetting properties of gallium and gallium-based alloys.
• gallium and a gallium-based alloy have good or very good metal wetting properties, but poor ceramic and epoxy wetting properties. This is an important property that makes gallium-based alloys ideal for the present purpose, since the contact pads 2, 3 on the component 1 and test board 4 respectively are comprised of metal while surrounding material is either a ceramic or an epoxy material.
• gallium and gallium-based alloys Another important property of gallium and gallium-based alloys is that they will break down any oxide present on the contact pads 2, 3, due to the fact that gallium forms alloys with the material from which the contact pads are comprised. This means that an extremely good electric contact is obtained, where the contact resistance is normally below 1 mohm.
• gallium and gallium- based alloys also applies to mercury.
• mercury or mercury alloys is/are used instead of gallium and gallium alloys
• the use of gallium or gallium alloys is preferred from an environmental and handling aspect. If mercury is used, measures must be taken with regard to the high vapour pressure of mercury and because of the toxicity of mercury compounds. For instance, the use of mercury would require the method to be carried out in a closed room in which the mercury compounds are recovered in a manner that is acceptable from a* health aspect and an environmental aspect.
• the component 1 is mounted in a frame 8 that carries the test board 4, so as to bring the component 1 into a predetermined position of alignment with the test board 4, see Figure 4.
• the frame 8 may include a bottom part 9 and a top part 10.
• the bottom part 9 will preferably have internal measurements that correspond to the external measurements of the component 1.
• the upper part 10 is preferably provided with an overlying arm 11 adapted to abut the upper side of the component.
• the illustrated frame includes pull springs 12, 13 that are adapted to draw the top part 10 down towards the bottom part 9 with a suitable force such as to press the component 1 against the test board with a force that will ensure that all contact pads 2 are in good abutment with the pads 3 on the test board. It has been mentioned above that in a fourth step of the inven ⁇ tive method the component is lifted from the test board upon completion of the test and the contact pads then cleaned.
• test board 4 is the circuit board on which the component 1 shall be finally surface-mounted in a predetermined position.
• the first, second and third method steps are carried out and the component is tested after having been placed in said predetermined position.
• the test shows that the component performs in the manner intended
• the component 1 is retained on the circuit board 4 with a flux applied to the contact pads 2 and 3, and the circuit board is then heated with the component in said position to a temperature at which the contact pads 2 of the component fuse to correspond ⁇ ing contact pads 3 on the circuit board 4.
• This temperature may be about 200°C.
• gallium and gallium alloys will fuse together with the material in the contact pads 2 and the contact pads 3.
• test board is also comprised of a circuit board 4 on which the component 1 shall finally be mounted in a predetermined position
• the component is also tested after having been placed in this predetermined position.
• the component is fixed mechanically in its intended position relative to the circuit board. Fixation of the component may be achieved with the aid of a frame, as shown in Figure 1, or in some other suitable manner.
• the component 1 is kept in said position when using the circuit board.
• the liquid metal remains in a liquid state during the use of the component and that the contact pads 2, 3 are thus not fused together.
• the drawbacks mentioned in the introduction are eliminated by the present invention.
• the inventive method can be applied cheaply.
• the method is highly effective with regard to high frequency testing and high testing speeds, owing to the fact that the contact resistance, the parasitic inductance and the parasitic capacitance are low.
• the method is easy to apply, since the contact pressure between the contact pads can be kept very low.

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• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Electric Connection Of Electric Components To Printed Circuits (AREA)
• Testing Of Individual Semiconductor Devices (AREA)
• Devices For Indicating Variable Information By Combining Individual Elements (AREA)

Applications Claiming Priority (3)

Publications (1)

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ID=20403130

Family Applications (1)

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• 1996
  • 1996-06-24 SE SE9602486A patent/SE515851C2/sv not_active IP Right Cessation
• 1997
  • 1997-06-23 WO PCT/SE1997/001124 patent/WO1997050001A1/sv not_active Application Discontinuation
  • 1997-06-23 EP EP97930946A patent/EP0907893A1/en not_active Withdrawn
  • 1997-06-23 JP JP10502836A patent/JP2000513096A/ja active Pending

Non-Patent Citations (1)

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