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Abstract: In the mixed PCB production of DIP plug-in and bottom chip components, the impact of solder wave during wave soldering frequently causes displacement and falling-off of surface-mount resistors and capacitors, which is a common defective issue in mass PCBA production. As the core tooling of this process, the red glue printing stencil requires targeted through-hole pin avoidance opening design to eliminate hidden troubles such as hole blockage, glue overflow, component falling off and cold solder joints. This article elaborates on two mainstream processes of plastic stencils and integrated aluminum alloy open-hole stencils, component adaptation requirements and process advantages and disadvantages, providing professional references for industrial DFM evaluation, stencil selection and mass production yield improvement, while demonstrating the precision customization tooling technical strength of Suzhou ECLEN. 1. Plug-in Through-hole Avoidance Red Glue Stencil Technology: Plastic Stencil & Integrated Aluminum Alloy Open-hole StencilThe core design logic of red glue stencils: Open red glue grooves only on the body area of chip components to completely cover the SMT pads; Precisely avoid and hollow out all plug-in through-holes and pin areas, which fundamentally prevents red glue from flowing into through-holes, polluting plug-in pads and blocking hole positions, and ensures dual quality of chip reinforcement and subsequent plug-in wave soldering. 1.1 Plastic StencilMade of high-temperature resistant engineering plastic plate (non-composite stone, non-glass fiber material), the stencil is integrally CNC precision cut to form glue grooves and through-hole avoidance holes, serving as an economical and entry-level tooling solution for red glue printing. Core Features: Light weight, good anti-static and heat insulation performance; it avoids premature red glue curing caused by heat accumulation during printing. With short processing cycle and high cost performance, it is suitable for small-batch sampling, manual printing and medium and small-batch mass production scenarios. Process Control Points: Reserve sufficient safety margin in the through-hole avoidance area to adapt to plug-in pin space; Chamfer the inner wall of glue grooves to reduce red glue demoulding resistance and ensure uniform glue application.
Application Limitations: The plastic plate has slight thermal expansion and contraction, and is prone to wear and deformation after long-term high-frequency printing with general precision stability, so it is not suitable for high-precision and long-term mass production projects. Core Features: Light weight, good anti-static and heat insulation performance; it avoids premature red glue curing caused by heat accumulation during printing. With short processing cycle and high cost performance, it is suitable for small-batch sampling, manual printing and medium and small-batch mass production scenarios. Process Control Points: Reserve sufficient safety margin in the through-hole avoidance area to adapt to plug-in pin space; Chamfer the inner wall of glue grooves to reduce red glue demoulding resistance and ensure uniform glue application. Application Limitations: The plastic plate has slight thermal expansion and contraction, and is prone to wear and deformation after long-term high-frequency printing with general precision stability, so it is not suitable for high-precision and long-term mass production projects. Core Features: Light weight, good anti-static and heat insulation performance; it avoids premature red glue curing caused by heat accumulation during printing. With short processing cycle and high cost performance, it is suitable for small-batch sampling, manual printing and medium and small-batch mass production scenarios. Process Control Points: Reserve sufficient safety margin in the through-hole avoidance area to adapt to plug-in pin space; Chamfer the inner wall of glue grooves to reduce red glue demoulding resistance and ensure uniform glue application. Application Limitations: The plastic plate has slight thermal expansion and contraction, and is prone to wear and deformation after long-term high-frequency printing with general precision stability, so it is not suitable for high-precision and long-term mass production projects. 1.2 Integrated Aluminum Alloy Open-hole Stencil (ECLEN Mainstream Mass Production Process)Core Definition: Different from the traditional composite stencil of aluminum frame + stainless steel sheet, this process adopts integrated CNC precision milling and hole forming of aviation-grade aluminum alloy plate. It has no stainless steel sheet and no composite bonding structure, and the whole stencil is made of uniform aluminum alloy material. It is a high-end mass production solution for wave soldering red glue reinforcement process and a professional high-precision through-hole avoidance stencil in the industry. Core Technical Advantages: Integrated forming & zero deformation: The integral aluminum alloy plate processing brings strong structural rigidity without delamination and peeling risks, completely solving the deformation and offset problems of composite stencils and ensuring stable long-term printing precision. High-precision through-hole avoidance: Relying on high-precision CNC milling, it can accurately match dense through-holes, special-shaped pins and chip components with close spacing. The avoidance hole wall is smooth and burr-free, effectively preventing bad problems such as red glue overflow into through-holes and hole blockage. High temperature resistance, washable & long service life: Aluminum alloy material is high temperature resistant, anti-oxidation and anti-corrosive. It can withstand repeated high-temperature printing and ultrasonic cleaning without wear and deformation, greatly reducing tooling replacement costs. Anti-static & mass production compatible: With stable material performance, it adapts to automatic printing production lines and strong consistency in batch production, perfectly suitable for multi-variety and large-batch PCBA mixed production.
ECLEN Process Highlights: After receiving customers' original PCB materials, we carry out pre DFM manufacturability evaluation, accurately extract through-hole coordinates, component spacing and pin sizes, customize exclusive through-hole avoidance schemes, eliminate bad risks such as glue overflow, component falling off and poor plug-in soldering from the source, and provide one-stop customization services for integrated aluminum alloy open-hole red glue stencils. 2. Red Glue Printing + Wave Soldering Process | Component Adaptation and PCB Design RequirementsThe DIP plug-in + bottom SMT mixed wave soldering process relies on red glue curing to fix chip components and resist solder wave impact. It has strict requirements on component types and PCB layout, and insufficient preliminary evaluation will easily lead to batch defects. 2.1 Applicable Component Scenarios
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