A strong and lightweight composite packaging structure can be produced in an environmentally friendly and energy-efficient manner. It is necessary to develop methods for producing lighter, higher-quality paperboard with better strength and stiffness while retaining the same brightness. Energy efficiency is important when producing chemthermomechanical pulps (CTMP). The CTMP for paperboard should be designed to retain maximum bulk, therefor it is imperative to avoid unnecessary reductions in softening temperature when improving fiber stiffness. Optimizing the impregnation methodology of sodium sulfite (Na2SO3) in wood chips requires equally distributing softening properties across fibers. Wood fiber softening determines the efficiency of fiber separation during chip refining. Sulfonated lignin in the fiber walls and mid-lamellae determines the softening properties of these structures, as well as promoting stronger joint connections between fibers. However, evenly distributed sulfonation is difficult to achieve due to wood chips' differences in size, density, and quality. To determine how sulfonated lignin is distributed within and between individual fibers, we have employed XRF (X-ray fluorescence) techniques developed in-house and validated by beamline. Using our synchrotron measurements at APS, USA, we can gain a better understanding of sulfur distribution within and between wood fibers. As shown in the CTMP samples on images, there is an uneven distribution of sulfur between fibers. Typically, CTMP sulfur homogeneity inspections require spatial resolutions of 10µm-15µm. The methodology is developed based on the resolution containing homogeneity information. We believe that even the sulfonation along the fiber shell is the most favorable process parameter to extract. Identifying where the sulfonate ions (-SO3-) end up in the lignin of the wood fiber structure may therefore be an important element of future process and product development. We can, however, learn more about the development of fiber-joint strength and strength uniformity in products by characterizing sulfur distribution at the sub fiber level.