IPC-A-610E SOLDERING

MODULE OVERVIEW Soldering Acceptability Requirements Soldering Anomalies High Voltage

Module Objective Upon completion of this session, the participant will be able to identify the acceptability requirements for soldered assemblies and high voltage

Soldering Nature of the soldering process may dictate that an acceptable condition may have the same characteristics for all three classes Where appropriate, the type of soldering process used is addressed The connection criteria apply regardless of which methods • Resistance soldering apparatus. • Induction wave, or drag soldering. • Reflow soldering. • Intrusive soldering.

Exception : Some specialized soldering finishes require special acceptance criteria, not found in the IPC-A-610E Immersion Tin Palladium Gold Criteria should be based on design, process capability and performance requirements

Figure 5-1 Figure5-1 (A, B). As an exception, the solder connection to a termination may exhibit a wetting angle exceeding 90° Figure 5-1(C, D), when it is created by the solder contour extending over the edge of the solderable termination area or solder resist.

The primary difference between the solder connections created with processes using tin-lead alloys and processes using lead-free alloys visual appearance of the solder This standard provides visual criteria for inspections of both Figures specific to lead-free connections will be identified with the symbol shown in Figure5-3.

Soldering Acceptability Requirements Typical tin-lead connections - Shiny to a satin luster - Smooth appearance - Exhibit wetting as - concave meniscus between the objects being soldered. - High temperature solders - may have a dull appearance - Touch-up (rework) - Use discretion to avoid causing additional problems

Soldering Acceptability Requirements Target - Class 1,2,3 • Solder fillet appears generally smooth and exhibits good wetting of the solder to the parts being joined. • Outline of the lead is easily determined. • Solder at the part being joined creates a feathered edge. • Fillet is concave in shape. Acceptable - Class 1,2,3 • There are materials and processes, e.g., lead free alloys and slow cooling with large mass PCBs, that may produce dull matte, gray, or grainy appearing solders that are normal for the material or process involved. These solder connections are acceptable. • The solder connection wetting angle (solder to component and solder toPCB termination) do not exceed 90°, Figure 5-1 (A, B). – As an exception, the solder connection to a termination may exhibit a wetting angle exceeding 90°, Figure 5-1 (C, D), when it is created by the solder contour extending over the edge of the solderable termination area or solder resist.  

Soldering Anomalies – Exposed Basis Metal Acceptable - Class 1,2,3 • Exposed basis metal on: – Vertical conductor edges. – Cut ends of component leads or wires. – Organic Solderability Preservative (OSP) coated lands. • Exposed surface finishes that are not part of the required solder fillet area.

Soldering Anomalies – Exposed Basis Metal Acceptable - Class 1 Process Indicator - Class 2,3 • Exposed basis metal on component leads, conductors or land surfaces from nicks or scratches provided conditions do not exceed the requirements of 7.1.2.3 for leads and 10.3.1 for conductors and lands. Defect - Class 1,2,3 land surfaces from nicks, scratches or other conditions exceed the requirements of 7.1.2.3 and 10.3.1.

Soldering Anomalies – Pin Holes/Blow Holes Acceptable - Class 1 Process Indicator - Class 2,3 • Blowholes, Figures 8 and 9, pinholes, Figure 10, voids, Figures 11 and 12, etc., providing the solder connection meets all other requirements. Defect - Class 1,2,3 • Solder connections where pin holes, blow holes, voids, etc., reduce the connections below minimum requirements (not shown).

Soldering Anomalies – Reflow of Solder Paste Defect - Class 1,2,3 • Incomplete reflow of solder paste.

Soldering Anomalies – Nonwetting Defect - Class 1,2,3 • Solder has not wetted to the land or termination where solder is required. (Figures 17,18,19, component terminations, Figure 20, shield termination, Figure 21, wire termination.) • Solder coverage does not meet requirements for the termination type.

Soldering Anomalies – Cold/Rosin Connection Defect - Class 1,2,3 • The solder connection exhibits poor wetting and may show evidence of entrapped rosin separating the surfaces to be joined.

Soldering Anomalies – Dewetting Defect - Class 1,2,3 • Evidence of dewetting that causes the solder connection to not meet the SMT or through-hole solder fillet requirements.

Soldering Anomalies – Excess Solder Metal Lidded Components Solder splashes or tinning on a metalized package body, see Figure 27, should be evaluated for impact upon hermetic and radiation hardening performance of the component considering the intended performance environment. Solder splashes on the metalized surfaces may be acceptable if the extended electrical performance is not required or compromised.

Soldering Anomalies – Excess Solder – Solder Balls/Solder Fines Target - Class 1,2,3 • No evidence of solder balls on the printed wiring assembly.

Soldering Anomalies – Excess Solder – Solder Balls/Solder Fines Acceptable - Class 1,2,3 • Solder balls are entrapped, encapsulated or attached (e.g., in no-clean residue, with conformal coating, soldered to a metal surface, embedded in the solder resist or under a component). • Solder balls do not violate minimum electrical clearance.

Soldering Anomalies – Excess Solder – Solder Balls/Solder Fines Defect - Class 1,2,3 • Solder balls are not entrapped, encapsulated or attached or can become dislodged in the normal service environment. • Solder balls violate minimum electrical clearance.

Soldering Anomalies – Excess Solder – Bridging Defect - Class 1,2,3 • A solder connection across conductors that should not be joined. • Solder has bridged to adjacent noncommon conductor or component.

Soldering Anomalies – Excess Solder – Solder Webbing/Splashes Target - Class 1,2,3 • No solder splashes or webbing. Acceptable - Class 1,2,3 • Solder splashes or metallic particles meet the following criteria: – Attached/entrapped/encapsulated on the PCA surface or solder mask, or soldered to metallic surface. – Do not violate minimum electrical clearance.

Soldering Anomalies – Excess Solder – Solder Webbing/Splashes Defect - Class 1,2,3 • Solder webbing. • Solder splashes that are not attached, entrapped, encapsulated. • Solder splashes on metal component surfaces impact form, fit or function, e.g., damages lid seal on hermetic components. • Violate minimum electrical clearance.

Soldering Anomalies – Disturbed Solder Acceptable - Class 1,2,3 • Lead free and tin-lead solder connections exhibit: – Cooling lines, Figure 40. – Secondary reflow, Figure 41. Defect - Class 1,2,3 • Disturbed solder joint characterized by uneven surface from movement in the solder connection during cooling.

Soldering Anomalies – Fractured Solder Defect - Class 1,2,3 • Fractured or cracked solder.

Soldering Anomalies – Solder Projections Defect - Class 1,2,3 • Solder projection, Figure 47, violates assembly maximum height requirements or lead protrusion requirements. • Projection, Figure 48, violates minimum electrical clearance.