Solder Ball Loading via Gravity Drop and Mask Alignment

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Solution Overview

Problem

Conventional methods for loading solder balls onto printed wiring boards face challenges with small diameter balls, such as reduced yield due to attraction forces and varying bump heights, especially on uneven surfaces, leading to low quality and reliability.

Innovation Solution

A method and apparatus using a ball array mask with openings aligned to pads, combined with a cylinder member for suctioning and horizontally moving the mask and board to accurately drop solder balls onto pads, preventing contact damage and ensuring uniform bump heights.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If solder balls are suctioned by a suction head, then solder balls can be loaded onto electrodes, but small diameter solder balls are affected by attraction forces causing reduced yield

Engineering Contradiction:

Improveloading yieldVSAvoidattraction forces on small solder balls

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the harmful suction action that causes attraction forces and replaces it with a gravity-based dropping mechanism. Solder balls are placed on a mask and allowed to drop through openings onto electrodes, eliminating the suction head that creates harmful attraction forces on small diameter balls.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical suction system with a gravity-based system. Instead of using a suction head to pick up and place solder balls, the invention uses a mask with openings where solder balls are gravity-fed and drop onto electrodes, substituting mechanical suction with gravitational force.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Productivity

If solder balls are dropped onto electrodes using a ball array mask, then loading can be automated, but bump heights vary especially on uneven surfaces

Engineering Contradiction:

Improveloading automationVSAvoidbump height uniformity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies preliminary action by pre-positioning solder balls on a mask surface in alignment with electrode locations before the actual loading process. This preliminary arrangement ensures that each solder ball is correctly positioned to drop onto its corresponding electrode, maintaining precision while enabling automation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces a mask as an intermediary device between the solder ball supply and the electrodes. The mask with precisely positioned openings serves as a mediator that guides solder balls to the correct locations, ensuring uniform bump heights even on uneven surfaces while maintaining automated loading.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of manufacture

If conventional suction methods are used, then solder balls can be loaded, but contact damage occurs reducing quality

Engineering Contradiction:

Improveloading processVSAvoidcontact damage to solder balls

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent replaces the contact-based mechanical suction system with a non-contact gravity-based dropping system. Solder balls drop through mask openings onto electrodes without being touched by suction heads or other mechanical components, eliminating contact damage while maintaining ease of manufacture.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The mask serves as an intermediary that enables contactless transfer of solder balls. Instead of direct contact between suction heads and solder balls, the mask mediates the transfer process by allowing gravity-fed balls to pass through openings and land on electrodes without mechanical contact.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

This approach securely loads fine solder balls onto every pad without damage, achieving uniform bump heights and high reliability, even on uneven surfaces, with improved manufacturing yield and connection reliability.

Implementation Method 1

gathering the solder balls on the surface of the ball array mask under the cylinder member by suctioning air through the opening portion of the cylinder member

Methodology Applied

Scientific EffectSuction: Suction

Data Source

PatentUS8091766B2Method and apparatus for loading solder balls

Publication Date: 2012.01.10 IBIDEN CO LTD

AI summary

A solder ball loading apparatus for loading solder balls onto pads of a printed wiring board includes a holding device for holding a printed wiring board having pads and holding a ball array mask having of openings that correspond to pads of the printed wiring board, one or more cylinder members positioned over the holding device such that an opening portion of the cylinder member faces the holding device, the cylinder member gathering solder balls on the surface of the ball array mask under the cylinder member by suctioning air through the opening portion of the cylinder member, and a conveyor mechanism for moving the ball array mask and the printed wiring board relative to the cylinder member such that solder balls gathered under the opening portion of the cylinder member can be loaded onto the pads of the printed wiring board through the openings of the ball array mask held by the holding device.