Design Rules For Miniwave Drag Selective Soldering

Miniwave Drag Selective Soldering Design Rules 

 

  1. Introduction

Selective soldering is the process in which through hole components on a printed circuit board are processed by applying solder to individual sets of leads.  This process typically follows reflow of SMT components and therefore requires a great deal of precision and repeatability to avoid contact and damage to existing SMT components.  The selective solder process, by design, eliminates the need for “selective” pallets to protect SMT components as would be used in a wave solder process.

Selective soldering is the process in which components on a printed circuit board are processed by applying solder to individual sets of leads.

When a Printed Circuit Board (PCB) is designed with a selective solder process in mind, it provides a great advantage to the electronics assembly manufacturer as the number of defects and material cost is reduced significantly when compared to conventional wave or hand soldering operations.

To maximize the soldering results a certain number of process variables and conditions must be met.  The reliability of the selective soldering process depends on many of the following factors:

The following design guidelines provide a template for proper design of a PCB assembly to be soldered using a miniwave drag soldering process. 

                    Environmental Conditions

The environmental conditions are considered to be anything outside the process of materials or selective soldering machines operation that may have an impact on the performance of a selective soldering process.  Environmental conditions can be a fixed (temperature, humidity) or variable (facility layout, employee) and each condition have a specific approach to maximize a selective solder process.

 

  1. Pad Design For Through Hole Component

The through-hole PCB design is directly related to the lead pitch of the component chosen and may not provide the ability for independent adjustment, however, when available the following criteria should be used for plated through-hole design.

 

Centerline Pitch should be greater than 2.0 mm when possible

 

  1. Pad To Pad Tolerance

 

Keep away tolerance is important to protect surface mount components from contact with the solder wave as this will likely reflow the component and can cause displacement.  The keep away tolerance is not specific to surface mount pads and can also include components and other features that would be negatively affected if contacted by the molten solder wave.  The recommended keep away tolerances are as follows:

  1. Lead Protrusion

 

 

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