Microelectronics International

Reichl, H.

1986 Microelectronics International

doi: 10.1108/eb044238

Through the use of silicononsilicon packaging, VLSI chips can be interconnected by dense contacts and very fine conductor lines. Electrical and thermal properties obtained by means of this technique are discussed. The fabrication of small cooling channels in the silicon substrate and the application of the anodic bonding technique for chip mounting are demonstrated.

Loo, M.C.; Su, K.

1986 Microelectronics International

doi: 10.1108/eb044239

Due to oxide formation at the die backside, excessive nonwetting and voiding can occur especially for the larger die 100K sq. mil by gold eutectic die attach. Such voiding can cause die liftoff and cracking. Agglass seems to be a promising candidate. However, it has some shortcomings. First, solder seal hermeticity reject may occur due to nickel diffusing through gold metallisation and being oxidised on the surface of the multilayer package. Secondly, for those devices requiring backside contact, gold metallisation on the die backside becomes the barrier for the reaction between the silicon and the glass. The adhesion may be degraded. The factors which may overcome these shortcomings will be discussed.

Lejeune, B.

1986 Microelectronics International

doi: 10.1108/eb044240

Large ohm film resistors that guard sensitive telecommunication devices against the hazards of lightning require a set of exacting characteristics for tolerance, endurance, and productivity. These characteristics largely depend on how the resistor is trimmed. Conventional laser trimming is unable to provide all the requirements for this important resistor application. A new technique developed by Teradyne Inc. called Algorithmic Trimming employs an algorithm and data base to calculate realtime trim vectors that are used in a trimming hardware processor to overcome the drawbacks of conventional trimming. With this new technique 50ohm film resistors were trimmed to specification with 01 tolerance while attaining high resistor stability and a trim time of 300 milliseconds.

Bangert, H.; Kaminitschek, A.; Wagendristel, A.

1986 Microelectronics International

doi: 10.1108/eb044241

Hardness testing using a SEM offers visual observation and measurement according to the hardness definition even for submicroscopic impressions. It can provide information on plasticity, homogeneity, adhesion etc. which cannot be obtained from depth measurements alone. The device described operates inside a SEM and offers a load between 102N and 105N. The influence of test load, rate of load increase and dwell time on the results was examined on various materials.

Cadenhead, R.L.; Prokop, J.S.

1986 Microelectronics International

doi: 10.1108/eb044242

An outline is given of the purpose and activities of the ISHMUS Education Program. Guidelines for establishing and operating Student Chapters are provided, together with the benefits of membership, and several of the facilities made available to student members are described.

Storbeck, I.; Balke, H.; Wolf, M.

1986 Microelectronics International

doi: 10.1108/eb044243

The production of interconnection modules with an increasing number of layers leads to problems in the planarity of modules and therefore in the chip mounting process. The present paper discusses a model based on the theory of plates which allows the calculation of bowing degree in relation to the coefficients of thermal expansion i, Young's moduli Ei, the thicknesses hi, and the softening point of the glassy components in the thick film pastes. The calculated values are compared with experimental data for substrates built up as entirely covered model substrates of up to 7 layers of one type of paste conductor and dielectric, respectively and of alternately printed layers.

Hammershj, R.

1986 Microelectronics International

doi: 10.1108/eb044244

Automatic thickfilm conductor testing performed as a 100 test gives a number of advantages if used correctly and well adjusted to the real needs. Though improved yield in production is the essential benefit of automatic test, a number of advantages and perspectives reach other company divisions outside the thickfilm production area. A number of general guidelines help to define the need and calculate the justification figures for a given production. The quality of the test process itself, however, can be an important part of the calculations.

Ainsworth, P.A.

1986 Microelectronics International

doi: 10.1108/eb044245

Arising from discussions at the International Institute of Welding Solder Paste Committee, the influences of a number of testing variables on the tack strength of solder pastes have been examined using the load cell system on a Meniscograph Solderability Tester. As a result, a standard method of testing has been proposed.

Budweit, M.

1986 Microelectronics International

doi: 10.1108/eb044246

In various publications noble steel is mentioned as a possibility for use as a substrate in thick film technology processing. The possibility to cut, stencil and drill steel sheets to desired shapes and the attractive price difference compared with alumina as well as PC board materials justified an investigation. A variety of steel sheets in various formulations from various vendors is offered on the market as well as ceramic pastes for thick film applications. This investigation aims to find out the most suitable ceramic paste for coating steel substrates in a common thick film process.

Lynch, J.T.

1986 Microelectronics International

doi: 10.1108/eb044247

A review is given of the reliability of the ceramic chip carrier when solderattached to alumina thick film substrates. It is shown that no degradation occurs during humidity cycling or humidity steady state tests. Some diminution of the solder joint strength takes place during prolonged high temperature storage and temperature cycling but the effect is much more marked during power cycling. The effect of flux residues on thick film hybrids after solder reflow of surface mount components is assessed. No significant deterioration of any component, printed or discrete, that is attributable to flux is observed, given adequate cleaning techniques. The reliability of the ceramic leadless chip carrier is compared with both leaded ceramic and metal and plastic surfacemountable components. The compliant leads of packages offer some advantages over the leadless chip carrier where thermal excursions are important but the leads themselves are easily damaged. Plastic packaging for surfacemountable components continues to improve and become increasingly popular but potential reliability hazards associated with a thermal management performance inferior to that of ceramic and metal versions, moisture ingress and corrosion are seen to remain problem areas.