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Techniques for High Temperature Technologies

IP.com Disclosure Number: IPCOM000243295D
Publication Date: 2015-Sep-18
Document File: 4 page(s) / 73K

Publishing Venue

The IP.com Prior Art Database

Abstract

In technologies developed for the oilfield, the electronics must often withstand harsh environments, i.e. increasingly high temperatures combined with hot shocks and vibration. This can represent an issue, in particular in term of reliability, for the packaging and construction of electronics operating in downhole tools. The present techniques involve a high temperature substrate with double gold plating including using thick gold for gold wire-bonding and thin gold for aluminum wire-bonding. The present techniques also involve using a silicon film adhesive for attachment of ceramic HTCC substrates onto metallic packaging. The present techniques also involve using a temperature absorption barrier (TAB) as an interface between electronic die and ceramic substrates, with wire-bonding used in order to have a good electrical connection.

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Techniques for High Temperature Technologies

Abstract

In technologies developed for the oilfield, the electronics must often withstand harsh environments, i.e. increasingly high temperatures combined with hot shocks and vibration. This can represent an issue, in particular in term of reliability, for the packaging and construction of electronics operating in downhole tools.  The present techniques involve a high temperature substrate with double gold plating including using thick gold for gold wire-bonding and thin gold for aluminum wire-bonding.  The present techniques also involve using a silicon film adhesive for attachment of ceramic HTCC substrates onto metallic packaging.  The present techniques also involve using a temperature absorption barrier (TAB) as an interface between electronic die and ceramic substrates, with wire-bonding used in order to have a good electrical connection

Use of HTCC substrate with double Au plating

Thick Gold (>2 um thickness) for Gold wire-bonding and thin Gold (0,03 to 0,6 um thickness) for Aluminum wire-bonding

The technology and material choice for High Temperature electronic packaging is important to reach the challenging reliability targets. For the harshest mission profiles (typically when the temperature is higher than 175°C), gold plating HTCC substrates are typically used.  Wire-bonding is commonly performed today with gold ball wire-bonding on thick gold plating. Aluminum wire-bonding is often used to be compatible with Aluminum pads of dies and it presents higher reliability at high temperatures. For example, some electronic packaging uses flash Gold (0,03 to 0,6 um thickness) for Aluminum wire-bonding and thick Gold (>2 um thickness) for Gold wire-bonding.

            The present techniques involve HTCC substrates with double Gold thicknesses: flash Gold (0,03 to 0,6 um thickness) for Aluminum wire-bonding and thick Gold (>2 um thickness) for Gold wire-bonding.  The goal is to achieve a high reliability wire-bonding process at high temperatures and in hot shocks, in accordance to Down hole mission profiles.

HTCC substrates are plated with thick Gold (>2 um thickness) for Gold wire-bonding and thin Gold (0,03 to 0,6 um thickness) for Aluminum wire-bonding, on the layers: Nickel Phosphorus electro less and Nickel Boron electro less, as shown in the table of FIG. 1 below.

Plating structure

Thickness (um) for Alu wire-bonding

Thickness (um) for Au wire-bonding

Min

Max

Min

Max

Gold

0,03

0,6

> 2

 

Nickel Phosphorus electro less

7

10

7

10

Nickel Boron electro less

0,5

2,5

0,5

2,5

Figure 1- HTCC substrates plating

The flash Gold plating may be used to avoid the AuAl intermetallics growth and the Kirkendal voiding effect and to achieve higher reliability for the Aluminum wire-bonding process on Aluminum die pads. 

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