Multilayer Laminate Heating with Segmented Resistive Zones
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Solution Overview
Problem
Existing methods for manufacturing multilayer plastic laminates for printed circuits face issues with temperature uniformity, leading to peripheral packs being colder than the center, and increased assembly times due to the use of copper strips for heating, which results in some packs being discarded and slower temperature increase.
Innovation Solution
A method involving a stack of multilayer plastic laminates alternated with thermally conductive and electrically insulated separator plates, using a serpentine copper tape for heating, and auxiliary resistive heaters to ensure uniform temperature across the stack, with controlled pressure and heat application to harden adhesive layers and fix the layers together.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If copper strips are used for heating the stack of packs, then heating current can be generated to warm the laminate, but the peripheral packs become colder than the center packs by about 50-60°C
Solution Approach 1:
The heating system is segmented into multiple independent heating zones: upper heating plates, lower heating plates, and side heating plates. Each zone can be independently controlled to provide targeted heating to different regions of the stack, ensuring uniform temperature distribution across all packs including peripheral ones.
Solution Approach 2:
Different regions of the heating system are designed with different heating characteristics. The side heating plates specifically target the peripheral packs that were previously underheated, while the upper and lower plates handle the central regions. This localized heating approach ensures each region receives appropriate heat to achieve overall temperature uniformity.
2Temperature
If copper strips are used for heating, then heating can be achieved, but the assembly time increases and some packs must be discarded
Solution Approach 1:
Multiple heating functions are merged into a single integrated heating system. The upper heating plates, lower heating plates, and side heating plates work simultaneously as a unified system, providing comprehensive heating to the entire stack in parallel, thereby reducing total heating time compared to sequential or single-zone heating approaches.
Solution Approach 2:
The heating system is designed to pre-distribute heat to all regions of the stack simultaneously before the lamination process begins. The side heating plates specifically pre-heat the peripheral packs that would otherwise be neglected, ensuring all packs reach the required temperature uniformly before pressing, eliminating the need to discard underheated packs.
3Temperature
If copper strips are used for heating, then heat can be generated, but the temperature increase rate is slower compared to other heating methods
Solution Approach 1:
The heating system serves multiple functions simultaneously: the upper and lower heating plates provide primary heating, while the side heating plates provide supplemental heating to peripheral regions. This multi-functional heating system achieves both rapid temperature increase and uniform distribution, overcoming the limitations of single-function copper strip heating.
Solution Approach 2:
The heating approach transitions from one-dimensional (copper strips along the center) to three-dimensional heating by adding side heating plates that heat the peripheral regions from the sides. This dimensional expansion of the heating system enables simultaneous heating of all regions including corners and edges, dramatically increasing the overall temperature rise rate while maintaining uniformity.
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 achieves uniform temperature distribution throughout the stack, reducing the need to discard packs and increasing the number of usable packs, while also improving electrical contact reliability and assembly efficiency.
Implementation Method 1
generating heat inside the stack by making circulate an electric current in the serpentine metal tape, with resistive behavior
Implementation Method 2
two auxiliary resistive heaters...whose power dissipated is enough for compensating the temperature loss of the two ends of the stack
Implementation Method 3
separator plates that are thermally conductive and electrically insulated
Data Source
AI summary
In manufacturing multilayer plastic laminates for printed circuits, a press with two surfaces exerts pressure under vacuum on a stack of laminates, the packs, alternated with separator plates made of anodized aluminum. The packs include prepreg layers. The metalizations present on the two sides of each pack are portions of a copper strip repeatedly folded 180° around each pack and each separator plate. A strong current circulates in the copper strip which heats the strip with resistive behavior: the heat causes the close fixing of the various layers. An auxiliary heater is applied to each surface of the press by element of an interposed insulating plate. This includes an aluminum plate with equidistant longitudinal holes containing the same number of armored candle-like resistors, connected in parallel. A main power supply provides direct current to the copper strip, two secondary power supplies provide alternating current to the two auxiliary heaters.