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34-425: Soldering of BGA devices requires precise control and is usually done by automated processes such as in computer-controlled automatic reflow ovens . The BGA is descended from the pin grid array (PGA), which is a package with one face covered (or partly covered) with pins in a grid pattern which, in operation, conduct electrical signals between the integrated circuit and the printed circuit board (PCB) on which it

68-399: A dye , and after drying, the module is pried off and the broken joins are inspected. If a solder location contains the dye, then it indicates that the connection was imperfect. During development it is not practical to solder BGAs into place, and sockets are used instead, but tend to be unreliable. There are two common types of socket: the more reliable type has spring pins that push up under

102-571: A heat transfer liquid (e. g. PFPE ) condensing on the PCBs. The liquid used is chosen with a desired boiling point in mind to suit the solder alloy to be reflowed. Some advantages of vapour phase soldering are: This is also known as condensation soldering. Pressure curing ovens, or Autoclave, is widely utilized to minimize voiding and improve adhesion strength in bonding processes.  Pressure cure ovens are typically employed in die attach and underfill applications.  Increasing pressure during

136-419: A stub . You can help Misplaced Pages by expanding it . Interposer An interposer is an electrical interface routing between one socket or connection to another. The purpose of an interposer is to spread a connection to a wider pitch or to reroute a connection to a different connection. An interposer can be made of either silicon or organic (printed circuit board-like) material. Interposer comes from

170-425: A BGA design derivate with the functional equivalent of the balls there being called bumps or micro bumps. This is realized at an already microscopic size level. To make it easier to use ball grid array devices, most BGA packages only have balls in the outer rings of the package, leaving the innermost square empty. Intel used a package designated BGA1 for their Pentium II and early Celeron mobile processors. BGA2

204-424: A vacuum device for lifting the package. The BGA can be replaced with a new one, or it can be refurbished (or reballed ) and re-installed on the circuit board. Pre-configured solder balls matching the array pattern can be used to reball BGAs when only one or a few need to be reworked. For higher volume and repeated lab work, a stencil-configured vacuum-head pick-up and placement of loose spheres can be used. Due to

238-624: A widely accepted, cost-effective alternative to 3D ICs . There are already several products with interposer technology in the market, notably the AMD Fiji/Fury GPU , and the Xilinx Virtex-7 FPGA . In 2016, CEA Leti demonstrated their second generation 3D- NoC technology which combines small dies ("chiplets"), fabricated at the FDSOI 28 nm node, on a 65 nm CMOS interposer. Another example of an interposer

272-526: Is Intel's package for their Pentium III and some later Celeron mobile processors. BGA2 is also known as FCBGA-479. It replaced its predecessor, BGA1. For example, the "micro-FCBGA" (flip chip ball grid array) is Intel's current BGA mounting method for mobile processors that use a flip chip binding technology. It was introduced with the Coppermine Mobile Celeron. Micro-FCBGA has 479 balls that are 0.78 mm in diameter. The processor

306-407: Is a common gas used for this purpose. This minimizes oxidation of the surfaces to be soldered. The nitrogen reflow oven takes a few minutes to reduce Oxygen concentration to acceptable levels within the chamber. Thus nitrogen ovens typically have nitrogen injection in at all times which decreases defect rates. The heating of the PCBs is sourced by thermal energy emitted by the phase transition of

340-539: Is a solution to the problem of producing a miniature package for an integrated circuit with many hundreds of pins. Pin grid arrays and dual-in-line surface mount ( SOIC ) packages were being produced with more and more pins, and with decreasing spacing between the pins, but this was causing difficulties for the soldering process. As package pins got closer together, the danger of accidentally bridging adjacent pins with solder grew. A further advantage of BGA packages over packages with discrete leads (i.e. packages with legs)

374-551: Is affixed to the motherboard by soldering the balls to the motherboard. This is thinner than a pin grid array socket arrangement, but is not removable. The 479 balls of the Micro-FCBGA package (a package almost identical to the 478-pin socketable micro-FCPGA package) are arranged as the 6 outer rings of a 1.27 mm pitch (20 balls per inch pitch) 26x26 square grid, with the inner 14x14 region empty. Primary end-users of BGAs are original equipment manufacturers (OEMs). There

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408-606: Is also a market among electronic hobbyists do it yourself (DIY) such as the increasingly popular maker movement . While OEMs generally source their components from the manufacturer, or the manufacturer's distributor, the hobbyist will typically obtain BGAs on the aftermarket through electronic component brokers or distributors . Reflow oven A reflow oven is a machine used primarily for reflow soldering of surface mount electronic components to printed circuit boards (PCBs). In commercial high-volume use, reflow ovens take

442-455: Is maintained by a bubbler system that is monitored in real time to provide stable and consistent formic concentrations to within 0.5% in the process chamber. Formic acid reflow ovens employ sets of double doors at the oven’s entrance and exit to dramatically reduce process gas consumption.  During production, only one door opens at a time, thus isolating the process chamber and lowering nitrogen and formic acid consumption. Thermal profiling

476-431: Is placed. In a BGA the pins are replaced by pads on the bottom of the package, each initially with a tiny solder ball stuck to it. These solder spheres can be placed manually or by automated equipment, and are held in place with a tacky flux. The device is placed on a PCB with copper pads in a pattern that matches the solder balls. The assembly is then heated, either in a reflow oven or by an infrared heater , melting

510-402: Is relieved and the product cools. Pressure cure ovens can utilize air or nitrogen as the pressurizing agent. Traditional reflow can be augmented by the addition of a late-stage vacuum chamber.  Introducing a vacuum chamber to the reflow process allows voids and bubbles to escape, significantly reducing voiding in solder joints and interfaces. During the vacuum process, the circuit board

544-511: Is stationary, assuring no shifting parts.  Smooth travel into and out of the vacuum chamber, minimizing vibration, is critical. Employing heat inside the vacuum chamber allows peak temperatures to be achieved during vacuum, assuring shorter time above liquidous and greater process flexibility.  High vacuum chamber temperatures also prevent flux buildup inside the chamber. Advanced vacuum reflow ovens employ multiple conveyor systems allowing higher throughput by optimizing transfer time into

578-401: Is the act of measuring several points on a circuit board to determine the thermal excursion it takes through the soldering process. In the electronics manufacturing industry, SPC (statistical process control) helps determine if the process is in control, measured against the reflow parameters defined by the soldering technologies and component requirements. This industry -related article is

612-498: Is the adapter used to plug a SATA drive into a SAS backplane with redundant ports. While SAS drives have two ports that can be used to connect to redundant paths or storage controllers, SATA drives only have a single port. Directly, they can only connect to a single controller or path. SATA drives can be connected to nearly all SAS backplanes without adapters, but using an interposer with a port switching logic allows providing path redundancy . This electronics-related article

646-470: Is the lower thermal resistance between the package and the PCB. This allows heat generated by the integrated circuit inside the package to flow more easily to the PCB, preventing the chip from overheating. The shorter an electrical conductor, the lower its unwanted inductance , a property which causes unwanted distortion of signals in high-speed electronic circuits. BGAs, with their very short distance between

680-453: Is to put a "compliant layer" in the package that allows the balls to physically move in relation to the package. This technique has become standard for packaging DRAMs in BGA packages. Other techniques for increasing the board-level reliability of packages include use of low-expansion PCBs for ceramic BGA (CBGA) packages, interposers between the package and PCB, and re-packaging a device. Once

714-629: The Latin word "interpōnere", meaning "to put between". They are often used in BGA packages, multi-chip modules and high bandwidth memory . A common example of an interposer is an integrated circuit die to BGA, such as in the Pentium II . This is done through various substrates, both rigid and flexible, most commonly FR4 for rigid, and polyimide for flexible. Silicon and glass are also evaluated as an integration method. Interposer stacks are also

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748-525: The PCBs by means of convection and conduction . They may be fan assisted to control the airflow within the oven. This indirect heating using air allows more accurate temperature control than directly heating PCBs by infrared radiation, as PCBs and components vary in infrared absorptance . Ovens may use a combination of infrared radiative heating and convection heating, and would then be known as 'infrared convection' ovens. Some ovens are designed to reflow PCBs in an oxygen-free atmosphere. Nitrogen (N 2 )

782-399: The balls, although it does not allow using BGAs with the balls removed as the spring pins may be too short. The less reliable type is a ZIF socket , with spring pinchers that grab the balls. This does not work well, especially if the balls are small. Expensive equipment is required to reliably solder BGA packages; hand-soldering BGA packages is very difficult and unreliable, usable only for

816-456: The balls. Surface tension causes the molten solder to hold the package in alignment with the circuit board, at the correct separation distance, while the solder cools and solidifies, forming soldered connections between the device and the PCB. In more advanced technologies, solder balls may be used on both the PCB and the package. Also, in stacked multi-chip modules , ( package on package ) solder balls are used to connect two packages. The BGA

850-439: The conveyor speed and zone temperatures to achieve a known time and temperature profile . The profile in use may vary depending on the requirements of the PCBs being processed at the time. In infrared reflow ovens, the heat source is normally ceramic infrared heaters above and below the conveyor, which transfer heat to the PCBs by means of radiation . Convection ovens heat air in chambers, using that air to transfer heat to

884-424: The cost of visual X-ray BGA inspection, electrical testing is very often used instead. Very common is boundary scan testing using an IEEE 1149.1 JTAG port. A cheaper and easier inspection method, albeit destructive, is becoming increasingly popular because it does not require special equipment. Commonly referred to as dye and pry , the process includes immersing the entire PCB or just the BGA attached module into

918-411: The curing process removes voids. In a pressure cure process, air is pressurized in a rigid vessel or chamber while heating or cooling with forced convection.  Heaters, heat exchangers, and blowers are mounted internal to the pressure vessel, continuously circulating air across the pressure chamber providing consistent heat transfer to the product.  Upon completion of the curing process, pressure

952-444: The devices to the board through a process called "underfilling", which injects an epoxy mixture under the device after it is soldered to the PCB, effectively gluing the BGA device to the PCB. There are several types of underfill materials in use with differing properties relative to workability and thermal transfer. An additional advantage of underfill is that it limits tin whisker growth. Another solution to non-compliant connections

986-404: The form of a long tunnel containing a conveyor belt along which PCBs travel. For prototyping or hobbyist use PCBs can be placed in a small oven with a door. Commercial conveyorised reflow ovens contain multiple individually heated zones, which can be individually controlled for temperature. PCBs being processed travel through the oven and through each zone at a controlled rate. Technicians adjust

1020-455: The package and the PCB, have low lead inductances, giving them superior electrical performance to pinned devices. A disadvantage of BGAs is that the solder balls cannot flex in the way that longer leads can, so they are not mechanically compliant . As with all surface mount devices, bending due to a difference in coefficient of thermal expansion between PCB substrate and BGA (thermal stress) or flexing and vibration (mechanical stress) can cause

1054-412: The package is soldered into place, it is difficult to find soldering faults. X-ray machines, industrial CT scanning machines, special microscopes, and endoscopes to look underneath the soldered package have been developed to overcome this problem. If a BGA is found to be badly soldered, it can be removed in a rework station , which is a jig fitted with infrared lamp (or hot air), a thermocouple and

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1088-407: The smallest packages in the smallest quantities. However, as more ICs have become available only in leadless (e.g. quad-flat no-leads package ) or BGA packages, various DIY reflow methods have been developed using inexpensive heat sources such as heat guns , and domestic toaster ovens and electric skillets . Effectively also the flip chip methods for mounting chip dies to a carrier is sort of

1122-765: The solder joints to fracture. Thermal expansion issues can be overcome by matching the mechanical and thermal characteristics of the PCB to those of the package. Typically, plastic BGA devices more closely match PCB thermal characteristics than ceramic devices. The predominant use of RoHS compliant lead-free solder alloy assemblies has presented some further challenges to BGAs including " head in pillow " soldering phenomenon, " pad cratering " problems as well as their decreased reliability versus lead-based solder BGAs in extreme operating conditions such as high temperature, high thermal shock and high gravitational force environments, in part due to lower ductility of RoHS-compliant solders. Mechanical stress issues can be overcome by bonding

1156-421: The vacuum chamber, dual rail processing, and closed-loop vacuum pumps to prevent solder and flux spatter. Formic acid reflow ovens operate similarly to a traditionally reflow oven, with the addition of formic acid vapor injection into the key soak zones for flux-free reflow and vapor soldering.  Upon injection, the formic acid removes any oxides present on the metal prior to reflow. Formic acid concentration

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