DFM Analysis

Component Analysis will primarily include:

  • Component Height

Purpose: To provide a summary of component heights mounted on both sides of the board.


  • Component Pitch 

Components can be separated into groups according to their pitch size (the distance between centers of adjacent pads). Reviewing the distribution of pitch sizes provides an insight as to the level of technology of the board.


  • Component Rotation

Purpose: To provide a review of the various rotations of each component type. This helps forecast the assembly time and design for an optimal cycle.


  • Component Length Min. 

Purpose: To identify components smaller than the minimum value.


  • Componrnt Length Max. 

Purpose: To identify components longer than the maximum value.


  • Assembled Board Thickness 

Purpose: To identify locations where assembled board thickness (components on one or both sides and board thickness) is more than a set value.


  • Forbidden Type 

Some components can only be placed on one side of the board. The purpose of this check is to identify components not on the correct side of the board.


  • Component Spacing

Purpose: To identify components which are too close. Component spacing rules are essential in providing correct tolerances for assembly equipment. They are also important in allowing efficient rework. Distance between components heavily depends on component type, as well as the process employed (SMT reflow, flow solder, etc.).


  • Component Spacing by Height 

Purpose: To identify components which are too close considering their height. This is especially important in repair processes where tall components cause difficulty in accessing the close components. 


  • Component Under Component 

Not all component overlap is illegal. (SMT components can be placed under through hole components in some situations.) This category reports components partially or totally under other components. The same components are reported in ‘Comp. Spacing’ with a measurement value of zero when ERF variable v_split_c2c=No. Reporting such components in a separate category makes them easier to handle.


  • Component Overlap 

Report components that overlap other components. The overlap distance indicates how far a component should be moved to avoid overlapping.


  • Component to Toeprint 

Purpose: The distance between a component and the toeprint (pad) of an adjacent component is important to rework and soldering considerations. It provides a finer distinction than c2c (Component Spacing).


  • Other Side Area Keepout 

Purpose: To identify components (e.g. TAB, BGA) which should not have components or features on the opposite side because of heat dissipation considerations. Even though some small discrete components are allowed, the category provides a review mechanism.


  • Other Side Pins Keepout 

Purpose: To identify through hole components which should never have components on the other side too close to their pins.


  • Other Side Pads Keepout 

Purpose: To identify components with solder joints that are inspected by x-ray, and components on the other side of the board that could interfere with the inspection process.


  • Rout Spacing (Low Comp) 

Purpose: To identify components too close to the edge of the board. Milling and shearing equipment need physical space and may damage them if too close. The distance from the edge is typically smaller for low components, and larger for higher components.


  • Rout Spacing (High Comp) 

Similar to ‘Rout Spacing (Low Comp)’. To identify components too close to the edge of the board with heights greater than pp_low_height. Milling and shearing equipment need physical space and may damage them if too close. The distance from the edge is typically smaller for low components, and larger for higher components.


  • SMT Component To Conveyed Edge (Primary)

Purpose: To identify components too close to the edge of the board because when two SMT passes are needed, the second pass may knock them off.


  • SMT Component to Non-Conveyed Edge (Primary)

Purpose: To identify components too close to the edge of the board because when two SMT passes are needed, the second pass may knock them off.


  • Component to Conveyed Edge 

Purpose: To identify components too close to the conveyed edge since the SMT process requires a minimal clearance on the board edges to be handled by the conveyor.


  • Component to Non-Conveyed Edge

Purpose: To identify components too close to the non-conveyed edge.


  • Component to Silk Screen 

Purpose: To identify components where silk screen legends are placed too close. Silk screen features must be kept a minimum distance away from components to avoid coming in contact with the solderpaste.


  • Component to Reference Designator 

Purpose: To report components close enough to their RefDes’s in the silk screen layer. The component’s RefDes is a collection of silk screen features that draw the component name bearing Copper Text and Copper Text String attributes with the same value as the component name. When a reference designator is too far from the component, or does not exist at all, it becomes difficult to identify the component.


  • Component Without Reference Designator 

Purpose: To report components missing a RefDes.


  • RefDes Outside Profile

Silk screen features used as RefDes indicators are usually found close to their relevant components. Where indicators exist outside the profile, they are probably mistakes in design.


  • Misplaced Reference Designator 

Purpose: To identify RefDes’s which are misplaced or confusing. A RefDes is used to identify components on the board. Sometimes, the RefDes’s of two components are located in a way that is confusing (RefDes’s not in same order as component number). This could cause mistakes in assembly.


  • Multiple Reference Designators 

Silk screen features used as RefDes indicators are usually found close to their relevant components. Where multiple indicators exist, the farthest ones are probably mistakes in design.


  • Carrier Wall Spacing (Component) 

Purpose: To ensure there is enough space between components of two different process areas. When multiple processes are carried out on the same side, a carrier is used to shield SMT devices (assembled first) while the board passes through the flow solder stage. The design must leave enough room between components of two different process areas for the wall of the carrier to pass.


  • Carrier Wall Spacing (Toeprint) 

Purpose: To ensure enough space between a component and the toeprints of another component in a different process area on the other side of the board. ‘Carrier Wall Spacing (Comp.)’ only reports distances between two components of different process areas on the same side. This category reports components too close to a through hole toeprint of a component on the other side of the board. Through hole components within a process area on the top must also have a process area on the bottom of the board.


  • PTH to Carrier Wall 

Purpose: To ensure that plated through holes are not too close or under the carrier wall, since this adversely affects the sealing of the area protected by the carrier.


  • NPTH to Carrier Wall

Purpose: To ensure that non-plated through holes are not too close or under the carrier wall, since this adversely affects the sealing of the area protected by the carrier.


  • Label to Component 

Purpose: To ensure enough space between sensitive components and labels. Labels glued on the board (e.g. for barcoding) should be kept away from some fine-pitch components (e.g. soic). The existence of a label protruding above the board surface creates an uneven surface for the squeegee applying the solderpaste, and may cause uneven solderpaste application.


  • Component to Gold Fingers 

Purpose: To ensure that gold plating and other processes are adequately shielded from each other.


  • Component to Mounting Hole / Tooling Hole

Purpose: To keep components away from mounting holes / tooling holes This ensures they are not knocked or sheared off.


  • Component to Via 

If components near drill holes are too high, they can obstruct the solder flow to the hole.


  • Component to PTH 

If components near drill holes are too high, they can obstruct the solder flow to the hole.


  • Component to NPTH 

If components near drill holes are too high, they can obstruct the solder flow to the hole.


  • Hole Under Component 

Purpose: To ensure there are no holes under a certain type of component. Some components must not have any sort of drill underneath, especially small SMT (chip) components. They have a large placement tolerance and may end up with their terminators directly over the hole. The only holes allowed under through hole components are those of the component itself.


  • Hole Under Component Other Side 

PTHs under components on the other side of their process area could serve as a bridge during the solder flow process. They should be checked. The only holes allowed under through hole components are those of the component itself, or drills with attribute Capped Via.


  • Uncapped Via Under Component 

Purpose: To ensure there are no uncapped vias (a via not covered by solder mask) under a certain type of component. Uncapped vias used with wave flow soldering processes may result in bridging under components that cannot be visually inspected.


  • Capped Via Under Component 

Purpose: To ensure there are no capped vias under a certain type of component.


  • Wave Solder Component Orientation 

Purpose: To ensure uniform solder fill on both chip terminators.


  • Component Relative Orientation 

Purpose: To verify that during automatic assembly (from tape) of SMT components, there are not excessive rotations of the assembling arm to slow down assembly.


  • Component Uncommon Orientation 

Purpose: To flag all THMT components oriented in such a way as to conflict with the “majority” orientation (largest number of THMT components of the same c_type oriented in a like manner) on the board. Since many THMT components are assembled manually, such opposite orientations may be a source of assembly faults.


  • No Orientation Indication 

Reports components which have the attribute Orientation Indication Required but not an indication of pin #1 on the silk screen or copper layer. 


  • Wrong Orientation Indication 

The orientation mark indicates the position of pin #1. If there is more than one mark, or if it is wrongly placed, the component will be placed improperly.


  • No Square Pad on THMT Pin #1 

Purpose: To identify components lacking a square pad for pin #1’s toeprint. Polarity of THMT components is typically identified by square pads on the external signal layers.


  • Component Between Tall Components 

Components that are located between tall components are difficult to repair.


  • Component to Exposed Via 

Purpose: To avoid solder bridging between the exposed copper of a via and a component.


  • Trace Under Component 

Purpose: To detect lines under zero, stand-off components such as discrete or rpack components, lying close to the board. Lines underneath can interfere with proper placement of such components.


  • Copper Shape Under Component 

Purpose: To detect copper material under a component and not detected in the ‘Trace Under Component’ category. ‘Trace Under Component’ detects only lines and arcs. ‘Copper Shape Under Component’ detects pads and surfaces.