After the PCB board is produced, components need to be assembled before further delivery. Currently, common assembly methods include wave soldering, reflow soldering, and a combination of both. The quality of the PCB board significantly affects the assembly quality across these processes.
1. The impact of PCB quality on the reflow soldering process
1.1 Insufficient thickness of pad plating leads to poor soldering. The coating thickness on the pads for mounting components may be inadequate. Inadequate tin thickness during high-temperature melting results in insufficient solder, leading to inadequate bonding between components and pads. Based on our experience, the tin thickness on the pad surface should be >100μm.
1.2 Dirty pad surfaces prevent proper wetting of the tin layer. Improper cleaning of the board surface, such as insufficiently passing through the cleaning line, can leave impurities on the pad surface, resulting in poor soldering.
1.3 The wet film offset on the pad causes poor soldering. Wet film offset on the pads where components need to be mounted will also result in poor soldering.
1.4 Incomplete pads prevent components from being soldered firmly.
1.5 Unclean development of BGA pads, with residual wet film or impurities, leads to soldering without proper tin adherence during mounting.
1.6 Protrusion of BGA plug holes results in inadequate contact between the BGA component and the pad, making it prone to detachment.
1.7 Oversized solder mask around the BGA leads to exposed copper in the circuit connected to the pad, risking short-circuiting of the BGA module.
1.8 Incorrect spacing between positioning holes and patterns causes misalignment of printed solder paste, leading to short circuits.
1.9 Breakage of green bridges between IC pads with dense pins results in short circuits due to poor solder paste printing.
1.10 Protruding via plug holes next to ICs prevent proper mounting of the IC components.
1.11 Breakage of stamp holes between cells prevents the printing of solder paste.
1.12 Incorrectly drilled identification light spots on the wrong fork plate cause incorrect part placement during automated assembly, resulting in waste.
1.13 Secondary drilling of NPTH holes causes significant deviation of positioning holes, leading to misalignment of printed solder paste.
1.14 Light spots (next to IC or BGA) must be flat, matte, and without notches for smooth recognition by assembly machines, ensuring proper part attachment.
1.15 Mobile phone boards must not undergo nickel-gold reflow, as it causes serious unevenness in nickel thickness, affecting signal quality.
2. The Impact of PCB Quality on Wave Soldering Process
2.1 Presence of green oil in component holes results in poor soldering. No ring-shaped green oil should exceed 10% of the hole wall area in PCB component holes required for component insertion, with no more than 5% of holes containing green oil on the entire board.
2.2 Inadequate thickness of hole wall plating leads to poor soldering. Minimum requirements for hole wall coating thickness (copper, tin, gold, and ENTEK) must be met to avoid issues such as insufficient tin or air bubbles.
2.3 Excessive roughness of hole walls results in poor tinning or solder joint quality. Hole wall roughness should be less than 38μm to ensure uniform coating and adequate soldering.
2.4 Moisture in holes leads to virtual welding or air bubbles. Proper baking and packaging procedures are essential to prevent moisture buildup, ensuring reliable soldering during wave soldering processes.
2.5 Insufficient pad size results in poor soldering and potential damage to component holes and pads. Pad sizes should meet a minimum of 4 mil to ensure robust soldering connections.
2.6 Dirty hole interiors lead to poor tinning. Effective PCB board cleaning processes, including pickling of gold boards, prevent residue buildup that can compromise solder joint quality.
2.7 Inadequate hole aperture size prevents component insertion and proper soldering. Proper plating and cleanliness ensure that hole diameters remain within specifications for effective component mounting and soldering.
2.8 Misaligned positioning holes prevent component insertion and soldering. Precision in positioning hole alignment is crucial for accurate component placement and subsequent soldering.
2.9 Excessive board warpage affects soldering quality. Warpage levels should be within specified limits to prevent components from being improperly soaked in solder during wave soldering processes.
3. The Influence of PCB Quality on Hybrid Assembly Process
The quality of PCB boards significantly impacts hybrid assembly processes, particularly in cases where surface-mounted and through-hole components coexist. Proper control of soldering surface characteristics, including tin thickness and surface flatness, is critical to ensure reliable attachment of components during reflow, adhesive curing, and wave soldering stages. Specifically, avoiding polytin on tin-sprayed boards is essential to prevent component detachment during wave soldering.
1. The impact of PCB quality on the reflow soldering process
1.1 Insufficient thickness of pad plating leads to poor soldering. The coating thickness on the pads for mounting components may be inadequate. Inadequate tin thickness during high-temperature melting results in insufficient solder, leading to inadequate bonding between components and pads. Based on our experience, the tin thickness on the pad surface should be >100μm.
1.2 Dirty pad surfaces prevent proper wetting of the tin layer. Improper cleaning of the board surface, such as insufficiently passing through the cleaning line, can leave impurities on the pad surface, resulting in poor soldering.
1.3 The wet film offset on the pad causes poor soldering. Wet film offset on the pads where components need to be mounted will also result in poor soldering.
1.4 Incomplete pads prevent components from being soldered firmly.
1.5 Unclean development of BGA pads, with residual wet film or impurities, leads to soldering without proper tin adherence during mounting.
1.6 Protrusion of BGA plug holes results in inadequate contact between the BGA component and the pad, making it prone to detachment.
1.7 Oversized solder mask around the BGA leads to exposed copper in the circuit connected to the pad, risking short-circuiting of the BGA module.
1.8 Incorrect spacing between positioning holes and patterns causes misalignment of printed solder paste, leading to short circuits.
1.9 Breakage of green bridges between IC pads with dense pins results in short circuits due to poor solder paste printing.
1.10 Protruding via plug holes next to ICs prevent proper mounting of the IC components.
1.11 Breakage of stamp holes between cells prevents the printing of solder paste.
1.12 Incorrectly drilled identification light spots on the wrong fork plate cause incorrect part placement during automated assembly, resulting in waste.
1.13 Secondary drilling of NPTH holes causes significant deviation of positioning holes, leading to misalignment of printed solder paste.
1.14 Light spots (next to IC or BGA) must be flat, matte, and without notches for smooth recognition by assembly machines, ensuring proper part attachment.
1.15 Mobile phone boards must not undergo nickel-gold reflow, as it causes serious unevenness in nickel thickness, affecting signal quality.
2. The Impact of PCB Quality on Wave Soldering Process
2.1 Presence of green oil in component holes results in poor soldering. No ring-shaped green oil should exceed 10% of the hole wall area in PCB component holes required for component insertion, with no more than 5% of holes containing green oil on the entire board.
2.2 Inadequate thickness of hole wall plating leads to poor soldering. Minimum requirements for hole wall coating thickness (copper, tin, gold, and ENTEK) must be met to avoid issues such as insufficient tin or air bubbles.
2.3 Excessive roughness of hole walls results in poor tinning or solder joint quality. Hole wall roughness should be less than 38μm to ensure uniform coating and adequate soldering.
2.4 Moisture in holes leads to virtual welding or air bubbles. Proper baking and packaging procedures are essential to prevent moisture buildup, ensuring reliable soldering during wave soldering processes.
2.5 Insufficient pad size results in poor soldering and potential damage to component holes and pads. Pad sizes should meet a minimum of 4 mil to ensure robust soldering connections.
2.6 Dirty hole interiors lead to poor tinning. Effective PCB board cleaning processes, including pickling of gold boards, prevent residue buildup that can compromise solder joint quality.
2.7 Inadequate hole aperture size prevents component insertion and proper soldering. Proper plating and cleanliness ensure that hole diameters remain within specifications for effective component mounting and soldering.
2.8 Misaligned positioning holes prevent component insertion and soldering. Precision in positioning hole alignment is crucial for accurate component placement and subsequent soldering.
2.9 Excessive board warpage affects soldering quality. Warpage levels should be within specified limits to prevent components from being improperly soaked in solder during wave soldering processes.
3. The Influence of PCB Quality on Hybrid Assembly Process
The quality of PCB boards significantly impacts hybrid assembly processes, particularly in cases where surface-mounted and through-hole components coexist. Proper control of soldering surface characteristics, including tin thickness and surface flatness, is critical to ensure reliable attachment of components during reflow, adhesive curing, and wave soldering stages. Specifically, avoiding polytin on tin-sprayed boards is essential to prevent component detachment during wave soldering.