Liquid Ejection Head Dummy Holes for Flatness
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Solution Overview
Problem
Existing methods for manufacturing liquid ejection heads face challenges in securing surface flatness and controlling nozzle height, particularly in the boundary and interior portions of the ejection port forming region, leading to difficulties in achieving uniform liquid ejection performance.
Innovation Solution
The method involves forming dummy holes outside the ejection port forming region on the substrate, allowing uncured dry film resist to flow into both liquid supply ports and dummy holes, ensuring equivalent surface flatness and facilitating control of nozzle height through the use of a liquid path forming member and an ejection port forming member, which are created using negative photosensitive resins and processed using photolithography and dry etching techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dry film resist is transferred onto substrate to cover stepped portions of liquid supply ports, then liquid path layer can be formed, but surface flatness cannot be secured particularly in boundary portions
Solution Approach 1:
The invention introduces dummy holes in the liquid supply ports before transferring the dry film resist. This preliminary action ensures that the resist can flow uniformly into all ports including boundary portions, thereby securing surface flatness of the liquid path layer before the actual nozzle formation process begins
Solution Approach 2:
The invention applies different treatments to different regions of the liquid supply ports. Dummy holes are specifically added to boundary portions where surface flatness problems occur, while interior portions maintain their original structure. This localized modification resolves the surface flatness issue without unnecessarily complicating the entire structure
2Manufacturing precision
If liquid path layer is formed without sufficient surface flatness, then manufacturing can proceed, but nozzle height control becomes difficult
Solution Approach 1:
By introducing dummy holes before forming the liquid path layer, the invention preliminarily establishes uniform resist flow paths. This ensures that when the liquid path layer is subsequently formed, the baseline surface flatness is sufficient to enable precise nozzle height control in the final product
3Manufacturing precision
If uncured dry film resist flows into liquid supply ports, then liquid path forming member can be created, but surface flatness varies between boundary and interior portions
Solution Approach 1:
The invention adds dummy holes only to boundary portions of the liquid supply ports where surface flatness problems occur, rather than modifying all ports uniformly. This localized approach achieves uniform surface flatness across the entire substrate while minimizing the added structural complexity
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 enables the production of liquid ejection heads with uniform nozzle heights and improved surface flatness, resulting in enhanced liquid ejection performance and stability, as demonstrated by the formation of uniformly sized nozzles and accurate liquid path depths.
Implementation Method 1
a first liquid path forming member is formed on the first surface of the substrate, using a first dry film resist... an ejection port forming member is formed on the liquid path forming member... processed using photolithography
Data Source
AI summary
A liquid ejection head has an ejection port forming region which includes liquid ejection energy generating elements arranged on a substrate, liquid supply ports each running through the substrate and having an opening at a surface of the substrate, a liquid path formed on the surface as a space containing the liquid ejection energy generating elements and the liquid supply ports therein, and ejection ports corresponding to the respective liquid ejection energy generating elements. The liquid ejection head is manufactured by forming a liquid path forming layer on the substrate using a dry film resist, forming an ejection port forming layer on the liquid path forming layer, forming a liquid path in the liquid path forming layer and ejection ports in the ejection port forming layer. The substrate has dummy holes each having an opening at a surface of the substrate outside the ejection port forming region.