Probe-card multilayer wiring substrate and probe card
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Solution Overview
Problem
Conventional multilayer wiring substrates for probe cards face issues with thin film resistor deterioration due to thermal stress and heat accumulation, leading to structural complexity, increased manufacturing costs, and reduced reliability.
Innovation Solution
A multilayer wiring substrate design featuring an embedded heat sink with a heat dissipating portion outside the base insulating film, allowing heat to be transferred and dissipated efficiently, and a cover insulating film to simplify the structure without penetrating through-holes, combined with an exposed heat sink for enhanced heat dissipation and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal expansion/contraction suppression layer is embedded between insulating layers to suppress thermal stress, then thermal stress deterioration is suppressed, but heat dissipation is not promoted and the thin film resistor may still fuse
Solution Approach 1:
The heat dissipation function is segmented from the thermal stress suppression function. The thermal expansion/contraction suppression layer handles stress, while a separate heat dissipation hole provides thermal pathways, allowing each component to optimize its specific function without compromising the other.
Solution Approach 2:
The heat dissipation hole acts as an intermediary structure that introduces a thermal conduit through the insulating layers. This mediator enables heat to escape the thin film resistor region without interfering with the thermal expansion suppression function of the embedded layer.
2Reliability
If insulating layers with low thermal conductivity are used to insulate the thin film resistor, then electrical insulation is achieved, but heat generated at the resistor accumulates between layers causing deterioration
Solution Approach 1:
The heat dissipation hole creates a local region with high thermal conductivity within the otherwise low thermal conductivity insulating structure. This localized thermal pathway allows heat to escape from the thin film resistor without requiring the entire insulating layer to have high thermal conductivity, thus maintaining electrical insulation while preventing heat accumulation.
3Reliability
If the linear expansion coefficient of the suppression layer is made smaller than insulating layers to suppress thermal stress, then thermal stress is reduced, but the structure becomes more complex and manufacturing harder
Solution Approach 1:
The thermal expansion coefficient of the suppression layer is specifically selected to be smaller than that of the insulating layers, creating a parameter difference that suppresses thermal stress. This parameter optimization allows the use of conventional materials and processes while achieving the desired stress suppression effect.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design prevents thin film resistor deterioration, enhances reliability, and reduces manufacturing complexity and costs by efficiently dissipating heat while maintaining a simple structure.
Implementation Method 1
an embedded heat sink that is embedded to face the thin film resistor via the base insulating film and includes a material having a thermal conductivity higher than that of the base insulating film
Implementation Method 2
the embedded heat sink includes a heat dissipating portion that extends outside a region in which the thin film resistor is formed, and is not covered with the base insulating film
Data Source
AI summary
An object of the present invention is to provide a multilayer wiring substrate for probe card capable of preventing deterioration of a thin film resistor 30. Provided is a multilayer wiring substrate (an ST substrate) 15 for probe card, the multilayer wiring substrate being provided on a wiring path between an external terminal 120 and a probe 17 of a probe card 100, and having a base insulating film 41 formed on a top surface of the multilayer wiring substrate, in which the multilayer wiring substrate 15 includes: a thin film resistor 30 including a thin film formed on the base insulating film 41 and to which a pair of connection electrodes 33 are connected; an embedded heat sink 31 that is embedded to face the thin film resistor 30 via the base insulating film 41 and includes a material having a thermal conductivity higher than that of the base insulating film 41; and a cover insulating film 43 that is formed in a region corresponding to the thin film resistor 30 and covers the thin film resistor 30, and the embedded heat sink 31 includes a heat dissipating portion 50 that is not covered with the base insulating film 41 outside a region in which the cover insulating film 43 is formed.