Quad flat pack

Q, R) model, 1671 QC, see Quality circle QCD (quality, cost, and delivery), 552 QFD, see Quality function deployment QFP (quad flat pack), 424 Q1 teams, see Quality improvement teams Q-leaming, 1780 QLs (query languages), 119 QMS standards, see Quality management systems standards QoS, see Quality of service QR system, see Quick response system QS 9000 standard, 1973 Quad flat pack (QFP), 424 Quadratic programming problems (constrained optimization), 2555, 2562 Quality. See also Rehabihty in advanced planning and scheduling (APS), 2049... 

Figure 1.8 Diagram of a quad-flat pack (QFP) showing gull-wing leads for surface mounting.

Quad flat pack no lead (QFN), small outUne no lead (SON), Dual flat pack no lead (DFN)... 

Significant area reduction compared to quad flat packs... 

Numerous geometrical factors of the specific interconnection will also influence anisotropic adhesive formulation and processing, including lead planarity, IC pad metallization, and IC test patterns. The planarity of the leads on the substrate and/or device and the compliance of the conductive particles will determine if anisotropically conductive adhesives can be used in a particular application. For systems with large disparities between lead height, no electrical interconnection will be formed, as shown in Fig. 5. Fine-pitch IC packages for surface-mounted applications, such as the plastic quad flat pack (PQFP), often use gullwing leads that olfer much compliance to the joint. Even if the... 

Copper Cl 94 (taped and gold flash), wire bonded Near CSP format, excellent electrical and thermal characteristics MicroLeadFrame (MLF) and Quad Flat-Pack No-Lead (QFN) (Orient Semiconductor Electronics USA) Microwave, RF, and hand-held portable communications... 

MQFP—Metal Quad Flatpack. Sometimes used to refer to a plastic metric quad flat pack (such as Harris Corporation, Harris sold its semiconductor operations, now known as Intersil Corp.). MQuad, designed by the Olin Corporation, a high thermal dissipation aluminum package available in plastic leaded chip carrier (PLCC) and QFP packages (with 28-300 leads, and clock speeds of 150 MHz) (see Fig. 8.137). 

Shrink quad flatpack (or flat package) (SQFP), typically a 64-pin small quad flat package (1/4height of QFT) with a lead pitch of 0.016 in or less. Also known as quarter quad flat pack (QQFT). Square surface mounting (SSM). 

Basic SMD ICs come in a wide variety of packages, from 8-lead small outline packages (SOLs) to 208-lead quad flat packs (QFPs). Examples ofSO20 and QFP128 packages are shown in Fig. 11.18. 

Quad flat pack Any flat pack 1C package that has leads on aU four sides. 

Solder balls may also be a problem on no-clean assemblies. Solder balls are formed during reflow of solder paste when some solder is left behind when the solder melts and beads up and by spattering during wave soldering. These solder balls are usually washed off by solvent or water cleaning however, in a no-clean process they remain on the board. Solder balls can cause shorts by bridging the pads of small capacitors or resistors or the leads of fine-pitch quad flat packs. 

FIGURE 58.1 Diagram of a quad flat pack. Note the copper (Cu) leads that are attached by gold wire bonds to the die.This is the primary (or first-level interconnect) between the die and the package.The second-level interconnect will be created when the Cu leadframe is soldered to a motherboard via some type of surface-mount attach process. (Courtesy ofAmkor Technology, Inc.)... 

Many other variations of DIP technology are readily available, such as SH-DIP (shrink DIP), SIP (single in-line package), SOP (small out-package) and QFP (quad flat pack, as shown in Fig. lb (Courtesy of Shinko Electric Industries Co. Ltd)). The basic techniques are the same as DIP but the variants provide different form factors and different arrangement of the pins. 

A number of lead-free component termination finishes have been evaluated (Ref 13, 55) and used over the years. For passive components (such as chip capacitors and resistors), matte Sn plating has been used for many years with the tin-lead solder, and can be used with lead-free solder as well. For leaded components (e.g., quad flat pack or QFP), plating of matte tin or tin alloys may be used with lead-free solders (forward compatible). The tin whisker concern will be discussed in a later section. Nickel-lead has been used with the tin-lead solder for many years, and Ni-Pd-Au is currently an alternative for leaded components for lead-free soldering Ni-Pd typically does not provide as good wett-ahifity as tin. Area array packages with SAC halls are available and work well with the SAC solder. 

Kariya, Y. Hirata, Y. Otsuka, M. Effect of thermal cycles on the mechanical strength of quad flat pack leads/Sn-3.5Ag-X (X=Bi and Cu) solder joints. J. Electron. Mater. 1999, 28 (11), 1263-1269. 

The size of the particles in a solder paste determines the print characteristics, amongst other things. The particles are produced by a variety of methods, but they are most commonly made by dispersion of a stream of molten solder onto a rotating disk. The particles fall into a tank filled with an inert atmosphere where they solidify and then are collected at the bottom of the chamber. The collected particles are separated by size utilizing in a series of wire-mesh sieves. The mesh size is typically given in wires or holes per square inch. The Joint Industry Standard, J-STD-005, provides for solder paste particle size classification as listed in Table 1. The choice of solder-powder particle size for SMT applications is based on component pitch, part mix and pad arrangement. For example, the paste particle size required for an area array device is smaller compared to a peripheral-leaded device with the same pitch. A 0.5-mm pitch area array device may have 0.25-mm diameter pads which require a 0.25-mm to 0.3-mm stencil aperture to print a Type rv solder paste with an approximately at 60-80% transfer efficiency. Comparatively, a 0.5— mm pitch quad flat pack device would typically have an 0.2 mm to 0.2.5mm wide pad, but require a 0.15 to 0.2mm wide stencil aperture to print a Type III paste with approximately a 80 90% efficiency. 

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