Battery Pack PCB Layout With Via-Strap Contacts for Single-Side Assembly
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Solution Overview
Problem
The production of battery packs with printed circuit boards (PCBs) is costly due to the need for copper etching on both sides, which wastes material and increases time, as both sides require traces and components for electrical connections.
Innovation Solution
A battery pack design where all components and traces are mounted on one side of the PCB, using vias to connect the battery cell straps to the PCB, eliminating the need for copper etching on the opposite side and allowing single-pass wave soldering for assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If copper etching is performed on both sides of the PCB to create traces and test points, then electrical connections are achieved, but material cost and manufacturing time increase significantly
Solution Approach 1:
The patent extracts the electrical connection function from requiring copper etching on both sides of the PCB. By moving all traces to one side and using vias with solder pads on the opposite side for battery strap connections, the design eliminates the need for copper etching on the second side, thereby reducing material waste and manufacturing complexity while maintaining reliable electrical connections
Solution Approach 2:
The patent utilizes the third dimension (via holes penetrating through the PCB) to establish electrical connections. Instead of creating traces on both two-dimensional surfaces of the PCB, the invention uses vertical vias to connect the single-sided traces to solder pads on the opposite side, effectively solving the connection problem by adding a dimensional element
2Ease of manufacture
If all traces and components are placed on a single side of the PCB, then material cost is reduced, but assembly process complexity increases
Solution Approach 1:
The patent merges the functions of trace routing and component mounting onto a single side of the PCB. By placing all traces, test points, and components on one side while using vias for electrical connections to the opposite side, the design simplifies the PCB fabrication process and reduces material costs without significantly complicating the overall assembly when combined with wave soldering capability
3Productivity
If wave soldering is used to attach all components and battery straps in a single pass, then assembly time is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent prepares the PCB in advance by pre-drilling and plating vias, and pre-positioning all components and battery straps on the single side before the wave soldering process. This preliminary preparation ensures that when wave soldering is applied in a single pass, all solder joints are formed simultaneously with consistent quality, reducing assembly time while maintaining precision through proper process sequencing
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach reduces material costs and assembly time by eliminating unnecessary copper usage and simplifying the manufacturing process, while maintaining effective electrical connections.
Implementation Method 1
The battery pack includes a set of contacts, each contact having a U-shaped body including a center portion and at least one leg, each leg integrally formed with and approximately perpendicular to the center portion. The at least one leg extends from the second side of the PCB to the first side of the PCB through a corresponding hole and is soldered to the electrical trace extending from the corresponding hole.
Data Source
AI summary
A battery pack comprises a set of battery cells, a battery cell holder holding the battery cells, at least one battery strap having a first end connected to a terminal of one of the battery cells and a second end extending from the battery cell holder, a printed circuit board having a first side and a second side, components mounted on the second side of the printed circuit board, a trace on the second side of the printed circuit board extending from one components to a contact connected to the trace and mated with the second end of the at least one battery strap. Multiple vias extend from the first side to the second side, and the contact comprises a first portion having a through hole and a leg integrally formed with and approximately perpendicular to the first portion, the leg extending from the first side of the PCB to the second side of the PCB through a first via, the trace extending from the first via, the leg soldered to the second side of the PCB and the via and the through hole aligned with a second via adjacent to the first via, the through hole sized and configured to receive a PCB end of the strap, the PCB end of the strap soldered to the contact.