A replenishing solution for a cyanide-based electroless gold plating bath. The solution includes a gold(III) halide such as gold chloride, gold bromide, tetrachloroaurate (and its sodium, potassium, and ammonium salts), and tetrabromoaurate (and its sodium, potassium, and ammonium salts). The replenishing solution also may include an alkali (such as potassium hydroxide, sodium hydroxide, and ammonium hydroxide) to maintain the pH of the solution between 8 and 14. Also provided is a method of replenishing a cyanide-based electroless gold plating bath with the solution of the present invention.

Method of replenishing electroless gold plating baths

An apparatus and a method for electroplating pin grid array (PGA) packaging modules by utilizing a compressible member and an electrically conductive foil for providing electrical connections to the pins such that all the critical areas of the pins, the wire bond pads, the seal band and the die cavity are electroplated simultaneously through the connection to the pins.

Apparatus and method for electroplating pin grid array packaging modules

A non-dimensional correlation has been developed for the external thermal characteristics (case-to-air thermal resistance) of a surface mount metal quad flat pack in the mixed convection regime. This correlation uses Reynolds, Prandtl and modified Nusselt and Raleigh numbers, and is based on the model proposed by Churchill for correlating heat and mass transfer from simple surfaces, like flat plates. This modified Nusselt number can be interpreted as a non-dimensional external (case-to-air) thermal resistance. Cavity-down type 28 mm 208-leaded metal quad flat packs were tested to determine their thermal characteristics over a range of powers and air flow velocities. All the data up to 2 m/s air flow velocity was fitted to the proposed non-dimensional correlation with a maximum deviation of 5%. Such a non-dimensional correlation for the thermal characteristics of electronic packages provides a convenient basis for interpolating and extrapolating the test data. It also provides a simple way for using the laboratory test data at nominal temperatures and sea level conditions to estimate the thermal performance at higher temperatures and altitudes. This paper describes the tests that were done for characterizing the thermal performance of surface mount metal quad flat packs, and reviews the development of the non-dimensional correlation to represent the external thermal resistance. >

A non-dimensional correlation for the external thermal characteristics of surface mount metal quad flat packs

Al metal substrate with an anodic film separating the circuitry from the metal plate was developed by the means of anodization in this study. It was shown that an anodic film around 20–30 μm thickness possessed the better properties, the resistivity was greater than 1014 Ω cm, the dielectric constant was about 7 and the breakdown voltage exceeded 1000 V, which could satisfy the needs of the packaging. Electroless copper plating was attempted to complete the metallization of the anodized Al substrate, on which a fine Cu deposit could be obtained when the anodic film was sealed in a bath containing Ni, F ions.

Study of anodized Al substrate for electronic packaging

The MQUAD microelectronic package was developed to provide a high level of thermal performance for high leadcount integrated circuits./sup 1/ A numerical, lumped-parameter transient thermal model has been developed which accurately predicts the temperature of the die and other components of an MQUAD package in situations in which the power to the die changes. Examples of such situations are the power-up and power-down cycles and power excursions. The model is used to predict the behavior of a 160 lead, cavity-down MQUAD package in these situations under conditions of low and high circuit board conductivity and natural and forced convection. The predictions of the model are shown to be in good agreement with experimental values for representative situations. >

Transient thermal model for the MQUAD microelectronic package

This paper describes the design and development of MQUAD technology. The MQUAD packaging system is a high performance reliable technology currently in use for packaging of microprocessors, high-speed ASIC devices, including CMOS, Bi CMOS, Bi polar, gallium arsenide, and other high performance IC's. The packaging technology is being used for devices dissipating up to 14 watts and switching speed of up to 300 MHz. The design and development was carried out with the objectives of high thermal performance (up to 15 watts), high electrical performance (inductance and capacitances lower than comparable PQFPs) and reliability superior to the PQFPs. The approach taken was; to use an adhesively bonded metal package. An aluminum alloy lid and base were chosen to give excellent heat dissipation ability, mechanical integrity and light weight construction. A special anodization process was developed to put a hard, electrically insulating black colored anodic film on the aluminum alloy components. The adhesive seal is a filled epoxy having low dielectric constant and low ionic content and with excellent adhesion to both copper alloys and aluminum anodic films, especially in moist environments. The leadframe chosen is a high-strength, thermally conductive copper alloy. The assembly process for the MQUAD package emulates the PQFP assembly process except that the molding step is replaced by a single step pad attach simultaneous with the seal adhesive lamination/cure process. The leadframe pad is attached to the anodized aluminum alloy base via a silver-filled epoxy paste. The package was thoroughly tested for reliability and fully characterized for thermal and electrical performance. Reliability tests performed include temperature cycling, thermal shocks, solvent resistance, flammability, pressure cooker, and vapor phase shocks. Reliability of MQUAD packages is superior to that of PQFPs. Characterization includes /spl theta//sub ja/ and /spl theta//sub jc/, and resistance, inductance and capacitance measurements. Thermal and electrical performance of MQUAD packages equal or exceed that of comparable plastic or ceramic QFPs. The high reliability and performance of MQUAD was confirmed by many customers and users and has been published. Because of these benefits, the technology is being further extended to advanced packages such as MCMs, TAB and ball or pad grid arrays. >

D. Mabulikar

Papers

Development of a cost-effective high-performance metal QFP packaging system