Study On The Thermal-bonding Of Polyetherimide Manifold Plate

The manifold plate is functionally equivalent to the PCB board of integrated circuit system,which can integrate a variety of liquid circuit appliance parts into one board,and the in-board flow channel is directly connected to the integrated components.It is widely used in IVD and biological sciences.Since the manifold plate generally has a closed internal channel,it is difficult to directly form it by traditional processing methods at one time using traditional processing methods.So it has to be made into component parts,and then a complete product is formed by bonding.However,due to the particularity of the material of the manifold plate and the complexity of the structure,there are many problems in the bonding work that need to be solved urgently.In-depth research on this is conducted in this article.The material of the manifold plate is polyetherimide,which has a high glass transition temperature and the thickness of the manifold plate is large.The feasibility test of thermal bonding of complete manifold plate and polyetherimide thin sheet was investigated by using a simple plate mold.Although in the experiments of two stages,the bonding trace of manifold plates and simple sheets was obvious and the bonding quality was poor,it was proved that the thermal bonding of polyetherimide manifold plate was feasible,which provided a good start for the design of dedicated bonding device and bonding experiments.In order to solve the pressure and temperature control problems in the process of manifold plate thermal bonding,a set of special experimental mold was designed and fabricated.A innovated method was proposed that placing gaskets with different thicknesses on the bottom of the manifold plate to make the gasket and the manifold plate as a whole higher than the lower mold plane at different heights,so as to achieve different pressure on the manifold plate when the mold is closed.The temperature field of the mold was analyzed and calculated,and a temperature control system was built to accurately control the temperature of the upper and lower molds.The bonding mold,temperature control system and fully automatic stamping and stretching two-in-one forming machine were used together to form a polyetherimide manifold plate thermal bonding special device.The designed special bonding device was used to thermally bond the manifold plate.In order to find out the reason for the closed bubbles appeared in the part of the manifold plate during bonding,thermo-gravimetric analysis of polyetherimide material was carried out,and the results showed that: the initial thermal decomposition temperature of polyetherimide material is consistent with the bonding temperature of bubbles appearing inside the manifold plates after bonding.So the bubbles in the manifold plates are generated by nucleation ofthermal decomposition products of polyetherimide material,thus determining the bonding temperature range.Taking the change of the length and thickness of the manifold plate as the evaluation target,multiple parameters such as bonding temperature,bonding time and compression thickness were selected to design multiple sets of experiments,and the relationship between bonding parameters and bonding quality was experimentally studied.The comprehensive experimental results showed that: the bonding temperature of 210 ℃,the bonding time of20 min,and the compressed thickness of 0.05 mm are the set of bonding parameters that minimize the overall deformation of the manifold plate after bonding.In addition,after measurement,the microchannel deformation of the manifold plate can also meet the requirements under the experimental parameters adopted in this paper.An effective solution for the bonding of polyetherimide manifold plate is proposed by the research content and results of this paper,and reference significance for the bonding of other high temperature resistant polymer products is provided by this paper.